ANSI/IEEE C57.92-1981
guide for loading
mineral-oil-immersed power transformers
up to and including 100 MVA with
55°C or 65 °C winding rise
....
<Xl
C"l
....
N
�
I'
It)
(.)
w
w
w
-CI)
z
«
December 14,1981
SH06031
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
An American National Standard
IEEE Guide for Loading
Mineral-Oil-Immersed Power Transformers
Up to and Including 100 MV A with
55°C or 65°C Average Winding Rise
1. Scope
2. References
1.1 This guide covers general recommendations
for loading mineral-oil-immersed power trans­
formers, manufactured in accordance with
ANSI
C57.12.10-1976
[1] 1
and ANSI
C57.12.30-1977 [2] and other oil-insulated
power transformers up to and including 100
MVA maximum nameplate rating. It is based
mostly on aging of the winding insulation.
[1] ANSI C57.12.10-1976, American National
S t a ndard Requirements for Transformers
230 000 V and below, 833/958 through
8333/10417 kVA Single Phase, 750/862
through 60 000/80 000/100 000 kVA Three
Phase 2
[2] ANSI C57 .12.30-1977, American National
Standard Requirements Load-Tap-Changing
Transformers 230 000 V and below, 3750/
4687 through 60 000/80 000/100 000 kV A
Three Phase
Loading of transformers larger than 100 M VA
may be limited by factors other than insulation
aging such as stray flux, etc. When it is known
that such limitations do not exist and insula­
tion aging rather than oil temperature, gassing,
tank heating, etc is the controlling factor, this
guide may be used. This guide may also be used
for askarel filled transformers.
[3] ANSI/IEEE C57 .12.00-1980, General Re­
quirements for Liquid-Immersed Distribution,
Power, and Regulating Transformers
[4 ] ANSI/IEEE C57.91-1981, Guide for
Loading Mineral-Oil-Immersed Overhead-Type
Distribution Transformers with 55°C or 65°c
Average Winding Rise
1.2 Recommendations for transformers with an
insulation system which conforms to the 65°C
curve shown in Fig 1, those rated at an average
winding temperature rise of 65°c and a
hottest-spot temperature rise of 80°C, are
contained in Section 4 of this guide. Recom­
mendations for transformers with an insulation
system which conforms to the 55 °c curve
shown in Fig 1, those rated at an average
winding temperature rise of 55°C and a
hottest-spot temperature rise of 65 DC, are
contained in Section 5 of this guide.
3. General
Limitations
3.1.1 It must be recognized that there may
be limitations to loads above rating which a
transformer can carry other than the capacity
of the windings and cooling system. Among
these limitations are: oil expansion, pressure in
sealed units, bushings, leads, tap changers and
stray flux heating as well as the thermal
capability of associated equipment such as
cables, reactors, circuit breakers, disconnecting
switches, and current transformers. High am­
bient temperatures will also restrict a trans­
former's loadability. Any of these items may
limit loading and manufacturers should be
3.1
1. 3 The method used for computer calculation
of the Capability Tables for Normal and
Moderate Sacrifice of Life in Section 4 and
Section 5 of this guide and examples for
developing them by hand calculations are
contained in Section 6 and Section 7.
2 A NS I d oc uments are available from The American
National Standards Institute, 1430 Broadway, New
York, NY 10018.
IThe numbers in brackets correspond to the refer­
ences listed in Section 2 of t his guide.
9
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92-1981
IEEE GUIDE FOR LOADIN G MINERAL-OIL-IMMERSED POWER
consulted for advice on such limitations. Any
transformer that is expected to carry heavy
loads where the top-oil temperature may reach
limiting values should have good oil with a
flash point of not less than 145°C since the oil
in the cooling ducts adjacent to the windings
may exceed the top-oil temperature by a
number of degrees.
Operation at hottest-spot temperatures above
140 C may cause gassing in the solid insula­
tion and oil. Gassing may produce a potential
risk to the dielectric strength integrity of the
transformer and this risk should be considered
when the guide is applied.
3_1.2 Transformers are sometimes installed in
indoor vaults with natural ventilation_ This
type of installation results in a higher ambient
temperature than the outdoor air. The increase
in effective ambient temperature for expected
transformer operation must be determined
before loading limitations can be estimated.
daily loss of insulation life which are in
addition to normal loss of insulation life.
3.3 Transformer Rated Output
3.3.1 The terms rating, rated output, rated
load and full load used in this guide refer to
nameplate rating.
3.3.2 The temperature rise on which the
rating of a transformer is based takes into
consideration the experience of the industry
regarding:
(1) Insulation life as affected by operating
temperatures
(2) The ambient temperature assumed to
exist throughout the life of the transformer
3.3.3 The actual output which a transformer
can deliver at any time in service with normal
life expectancy may be more or less than the
nameplate rating, depending upon the ambient
temperature and other operating conditions.
°
3.4 Aging of Insulation
3.4.1 Aging or deterioration of insulation is a
function of time and temperature. Since, in
most apparatus, the temperature distribution is
not uniform, that part which is operating at the
highest temperature will ordinarily undergo the
greatest deterioration. Therefore, in aging
studies it is usual to consider the aging effects
produced by the highest (hottest-spot) temper­
ature.
3.4.2 Much of the fundamental data on aging
of insulation at different temperatures has been
based on laboratory and model tests in which
the decrease in mechanical and electrical
strength has been measured. Under the auspices
of the IEEE, a series of life expectancy tests
were made under controlled conditions on
production. type
distribution transformers.
Data from these tests were used as the basis for
the distribution transformer Life Expectancy
Curves in ANSI/IEEE C57.91·1981. While
these are the best insulation life data available
at this time, they are not directly applicable to
power transformers. Because the end point
strength of insulation (the final strength of
aged insulation) must be greater in power
transformers and because model tests of power
transformers have not yet been reported, the
power transformer insulation life expectancy
curves were selected to be more conservative
than those used for distribution transformers.
The transformer life expectancy predictions
contained herein are based on the insulation
life expectancy curves shown in Fig 1 and do
3.2 Transformer Life Expectancy
3.2.1 Recommendations in this guide are
based on the life expectancy of transformer
insulation as affected by temperature and time.
3.2.2 Transformer life expectancy at various
operating temperatures is not accurately
known, but the information given regarding
loss of insulation life at elevated temperatures
is considered to be conservative and the best
that can be produced from present knowledge
of the subject. The word conservative is used in
the sense that the actual insulation life at any
temperature is expected to be not less than
indicated in this guide. The effects of tempera­
ture on insulation life are subject to further
investigation and new data may affect future
revisions of this guide.
3.2.3 In Tables 3(a)-3(u) and 5(a)-5(u) the
normal loss of life loads are loadings which
result in a daily loss of life equal to that of a
continuous winding hottest-spot temperature
of 110°C and 95 °c for 65°C rise and 55°c
rise transformers, respectively . Normal life ex­
pectancy is 6.5 104 hours, a daily normal loss
of life of 0.0369%. Aging at other than rated
temperature is calculated using the equations
for power transformer insulation life expect­
ancy in Fig 1. The actual life should be
considerably greater than 6.5
104 hours for
the reasons mentioned in 4.1.2.4.
3.2.4 In Tables 3(a)-3(u) and 5(a)-5(u) the
moderate sacrifice of life expectancy values are
•
•
10
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
TRANSFORMERS UP TO
100
ANSI/IEEE
C57.92-1 981
°
MVA WITH 55 C OR 65 ° c AVERAGE WINDING RISE
�/
II;.uV
/
."
'"
<0
Ul
'"
::J
�
i:'
::J
-'
/
.,.
.,.
.,.
4
10
'"
0
z
'"
i%
,.,
'"
,.,
i ,-
.::
<0I,
�
c..,
&Q-
--.J
(!J�
!J
10
2
300280 260 240
220
200
r1
.,.
,.,
7%,
{�/j
'"
'"
'"
<l
lE
180
it'
/
I
;'
(()
/.,.
�
NATURAL LOG CONSTANTS
�
/
'3
I
.
Ju
140
120
B
A
65 °C RISE - 30 834 16054 0
II")
(/�
160
'"
55 °C RISE-32 543 16054.0
80
100
60
40
HOTTEST- SPOT TEMPERATURE IN 'C
RECIPROCAL OF ABSOLUTE TEMPERATURE SCALE
Fig 1
Life Expectancy Curve
not take into account deterioration of gaskets,
rusting of tanks, etc which result from factors
other than winding temperatures.
While the life expectancy curves are believed
to be conservative, any estimates of trans­
former life derived therefrom are intended only
as a guide.
304_3 Because the cumulative effects of tem­
perature and time in causing deterioration of
transformer insulation are not thoroughly es­
tablished, it is not possible to predict with any
great degree of accuracy the length of life of a
transformer even under constant or closely
controlled conditions, much less under widely
varying service conditions.
30404 The relation of insulation deterioration
to changes in time and temperature is assumed
to follow an adaptation of the Arrhenius
reaction rate theory which states that the
logarithm of insulation life is a function of the
reciprocal of absolute temperature:
LoglO (hours of life)
=
A+B
T
(Eq 1)
where
T
=
absolute temperature in
degrees Kelvin (8hs + 273)
8hs
=
hottest-spot temperature, 0 C
A and B
=
constants from desired life
expectancy curve
A and B values for both IOglO and loge are
shown on Fig 1.
11
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IE EE
C57.92-1 981
IEEE GUIDE FOR LOADING M IN ERAL-OIL-IMM ERS ED POWER
These ambients should be used as follows:
for loads with normal life expectancy, use item
(1) as the ambient for the month involved; for
short-time loads with moderate sacrifice of life
expectancy, use item (2) for the month in­
volved.
During any one day the average or maximum
temperatures may exceed the values derived
from (1) or (2) above. To be conservative, it is
recommended that these temperatures be in­
creased by 5 a C since aging at higher than
average temperature is not fully compensated
by decreased aging at lower than average
temperature. With this margin the approxi­
mated temperature will not be exceeded on
more than a few days per month and, where it
is exceeded, the additional loss of life will not
be serious.
3.5.2 Influence of Ambient on Loading for
Normal Life Expectancy. Average ambient
temperatures should cover periods of 24 h with
maximum temperatures not more than 10 aC
greater than average temperatures for air and
5°C for water. Table 1 gives the increase or
decrease from rated loads for other than
average daily ambients of 30°C for air and
25 a for water. It is recommended that the
5°C margin described in 3.5.1 be used when
applying the factors from Table 1. It should be
pointed out that the increase or decrease
obtained from Table 1 is more conservative
than the corresponding values shown in Table
3(a)-3(u) and 5(a)-5(u) which are based on
Tables 2 and 4 (assumed transformer char-.
acteristics), and therefore do not check these
tabulations exactly. Table 1 is for quick ap­
proximations.
Loading on the basis of ambient temperature
with loads permitted in Table 1 will give
approximately the same life expectancy as if
transformers were operated at nameplate rating
and standard ambient temperatures over the
same period.
Table 1 covers a range in ambients of 0 °c to
50°C for cooling air. A check should be made
with the manufacturer before loading on the
basis of ambient air less than 0 °c or greater
than 50°C.
Since ambient temperature is an important
factor in determining the load capability of a
transformer, it should be controlled for indoor
installations by adequate ventilation and
should always be considered in outdoor instal­
lations.
3.4.5 The many variables mentioned, and
particularly the many varying conditions of
load and ambient to which a transformer can
be subjected in service, make it impossible to
give definite rules for the loading of trans­
formers. It is possible to give only suggested
loadings under specified conditions with the
expectation that the user will adjust this
information to suit his particular application.
3.5 Ambient Temperatures and Its Influence
on Loading. Ambient temperature is an impor­
tant factor in determining the load capability
of a transformer since the temperature rises for
any load must be added to the ambient to
determine operating temperatures.
Transformer ratings are based on a 24 h
average ambient of 30 aC. This is the standard
ambient used in this guide.
The ambient temperature to be used for
water-cooled transformers is the cooling water
temperature plus an added 5°C to allow for
possible loss of cooling efficiency due to
deposits on cooling coil surfaces of water­
cooled transformers in service.
Whenever the actual ambient can be meas­
ured, such am bients should be used in deter­
mining the transformer's temperature and
loadability.
The ambient air temperature seen by a
transformer is the air in contact with its
radiators or heat exchangers. In some instal­
lations the transformer may be outdoors but
surrounded by buildings or sound deadening
walls. This may result in recirculation of heated
air, the ambient should be adjusted accord­
ingly.
3.5.1 Approximating Ambient Temperature
for Air-Cooled Transformers. It is often neces­
sary to predict the load which a transformer
can safely carry at some future time in an
unknown ambient.
The probable ambient temperature for any
month may be approximated as follows from
reports prepared by the National Weather
Service of the US Department of Commerce
for various sections of the country:
(1) Average Temperature. Use average daily
temperature for the month involved averaged
over a number of years.
(2) Average of Maximum Daily Temper­
atures. Use average of the maximum daily
temperatures for month involved averaged over
several years.
12
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
TRANSFORMERS UP TO 100 MVA WITH
55
a
C
OR
65
a
C
ANSI/IEEE
AVERAGE WINDIN G RISE
C57.92-1981
Table 1
Loading on Basis of Temperatures
(Ambient other than 30 °C and Average Winding Rise Less than Limiting Values)
(For Quick Approximation)
(Ambient Temperature Range 0 ac to
50
°
C)
% of R ating
Ty pe of Cool ing
Decrease Lo ad for
E ach °c
H igher Temperature
Increase Load for
a
Each C
Lower Temperature
1.5
1.5
1.0
1.0
1.0
1.0
0.75
0.75
Self-cooled
- OA
Water-cooled
- OW
Forced-air-cooled- OA/FA, OA/FA/FA
Forced-oil-cooled - FOA, FOW and OA/FOA/FOA
3.6 Operation with Part or All of the Cooling
Out of Service. Where forced-cooling equip­
ment, such as pumps or fans or both, is used to
increase the cooling efficiency, the transformer
may be required to operate for some time with
this equipment inoperative. The permissible
loading under such conditions is given in the
following paragraphs.
For multi-rated transformers (OA/F A, OAf
FA/FA, OA/FOA/FOA) with all or part of the
forced cooling inoperative, use the nameplate
rating based on the cooling in operation and
load on this basis. When either the pumps or
the fans of a cooling unit are out of service, the
entire cooling unit should be considered inop­
erative.
For forced-oil-cooled (FOA or FOW) trans­
formers with all pumps or fans or both
inoperative, heeding the following guidelines
should prevent undue injury to the trans­
former: 3
(1) Rated load may be maintained for ap­
proximately 1 h following normal operation at
nameplate rating in a 30 °C ambient
(2) Rated load may be carried for approxi­
mately 2 h if started with windings and oil in
a 30 °c ambient.
(3) Rated voltage may be maintained for 6 h
at no load, following continuous operation at
nameplate rating in a 30 °C ambient with cool­
ing equipment in operation.
(4) Rated voltage may be maintained for
12 h at no load starting with windings and oil
in a 30 °C ambient
For forced-oil-cooled transformer (FOA or
FOW) ratings with part of the coolers in
operation, use the following reductions in
permissible loading:
%of
Total Coolers
in Operation
Permissible Load
in % of
Nameplate Rating
100
80
60
50
40
33
100
90
78
70
60
50
These permissible loads give approximately
the same temperature rises as would full load
with all cooling in operation.
3.7 Supplemental Cooling of Existing Self­
Cooled Transfonners. The load which can be
carried on existing self-cooled transformers can
usually be increased by adding auxiliary cool­
ing equipment such as fans, external forced-oil
coolers, or water spray equipment. The amount
of additional loading varies widely, depending
upon:
(1)
(2)
(3)
(4)
Design characteristics of the transformer
Type of cooling equipment
Permissible increase in voltage regulation
Limitations in associated equipment
No general rules ean be given for such
supplemental cooling, and each transformer
should be considered individually.
3
The oil temperature for large units may exceed
a
110 C. Che ck with the m anufa cturer for l im itations.
13
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92-1981
IEEE GUIDE FOR LOADING MINERAL-OIL·IMMERSED POWER
4. Transfonners Specified to have an Average
It should be recognized that, due to thermal
°
Winding Rise of Not More Than 65 C and
Hottest-Spot Winding Rise of Not More
Than 80 °c
lag in oil rise, time is required for a transformer
to reach a stable temperature following any
change in load. Therefore, higher peak loads
may be carried for short durations. This is
reflected in the loading tables and the basic
4.1 Basic Loading for Normal Life Expectancy
equations in 6.7.3.
4.1.1 Basic Conditions
If
(1) The basic loading of a transformer for
the
are not
characteristics
transformer
normal life expectancy is continuous loading at
accurately known, a maximum top-oil temper­
normal
ature derived from Fig 2 may be used as an
rated output
service
when
operated under
indicated
conditions as
approximation. Loading from Fig 2 is based on
in 2.1.1 (1),
ANSI/IEEE
a difference of 25°C between the hottest-spot
C57.1 2.00-1979 [3]. It is assumed that opera­
temperature and top-oil temperature at rated
2.1.1
and
(2),
2.1.1
(3)
of
30°C for
load for self-cooled transformers,
tion under these conditions is equivalent to
transformers
(133%
and
operation in a continuous ambient temperature
forced-air-cooled
of 30 °C for cooling air or 25 °C for cooling
under) and 35°C for forced-oil-cooled trans­
water. Normal life expectancy will result from
formers.
operating with a continuous hottest-spot con­
4.1.2.2 Continuous Loading on Basis of
Average Winding Test Temperature Rise. For
ductor temperature of 110°C (or equivalent
each °c
variable temperature with 120 °c maximum) in
because
of
the
A 5° margin is used t o provide a tolerance in
the
voltage
hottest-spot temperature
of
rise.
The
which
the
temperature
transformer can carry at 65°C rise. Since this
location. The hottest-spot allow­
may increase the loading beyond that contem­
ances are based on tests of laboratory models.
(3) The
measurement
loadability thus obtained is that
hazard when placing a temperature detector at
the proper
5° that the average
rated load by the percentages given in Table 1 .
temperature cannot be directly measured on
designs
of
the transformer load may be increased above
(2) The hottest-spot conductor temperature
determines loss of life due to loading. This
commercial
excess
in
winding test temperature rise is below 65°C,
any 24 h period.
plated by the designer, the limitations given in
at rated
3.1
load is usually taken as the sum of the average
be
should
before
checked
taking
full
advantage of this increased loadability.
winding temperature and a 15°C allowance4
Some transformers are designed to have the
for the hottest spot. For mineral oil-immersed
difference between the hottest-spot and aver­
transformers operating continuously under the
age conductor temperatures greater than the
foregoing conditions with normal life expect­
15°C allowance. This will result in an average­
ancy, this temperature has been assumed to be
winding temperature rise of less than 65 °C,
a maximum of 1 1 0°C.
4.1.2 Loading for Nonnal Life Expectancy
but the hottest-spot winding temperature rise
under Specified Conditions
4.1.2.1 Loading by Oil Temperature. Oil
transformers should not be loaded above their
temperature
alone should not be used
as
may be at the limiting value of 80 °C. Such
rating as outlined in this section. The manu­
a
facturer should be consulted for information
guide for loading transformers. The hottest­
on the hottest-spot allowances used for these
spot to top-oil gradient at full load should be
designs.
determined from factory tests using Eq 8 or,
This
condition
may exist
in trans­
formers with large differences (greater than
lacking data, a value should be assumed. The
30°C) between top- and bottom-oil temper­
full-load hottest-spot to top-oil gradient should
atures and may be checked approximately by
be corrected to that for the actual load carried
measuring the top and bottom radiator temper­
using Eq 7 or Fig 9. This gradient subtracted
atures. Whenever possible, data on hottest-spot
from 110°C will give the maximum permis­
and oil temperatures obtained from factory
sible oil temperature for nonnal life expect­
temperature tests should be used in calculating
ancy.
transformer
4If cooler inlet and outlet temperatures are available,
a better estimate of the h ottest-spot temperature is
p ossible by making an adjustment in the 15 0 C allow­
ance. C onsult with the manufacturer.
loadability
or
when
calculating
temperatures for loads above rating.
4.1.2.3 Loading on Basis of Short-Time
Loads above Rating. Transformers may be
14
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
TRANSFORMERS UP TO 1 00 MVA WITH
2.0
1.8
'"
0
0
..J
t:
z
:::>
0:
55 DC OR 6 5 ° C
'"
�
�
1.6
b,.
�
"'
a.
�
1.4
SELF COOLED
FORCED AIR
C
FORCED OIL
"'-
�
� �
"
�
40
30
20
A
B
�
1.2
10
ANSI/IEEE
C57.92·1981
AVERAGE WINDIN G RISE
�
�
�
� ��
��[\
70
60
50
80
90
TOP, OIL TEMP "C
Fig 2
Approximate Continuous Loading for Nonnal Life Expectancy D
65 C Rise Transfonners
operated
ature
for
above 110°C hottest-spot temper­
short
periods
provided
they
4.1.2.5 Basis for Nonnal Loss o f Life
Loading in Tables 3(a)-3(u). The transformer
are
operated for much longer p eriods at temper­
capabilities for nonnal loss of life in Tables
that thermal aging is a cumulative process and
atures that result in aging equ h;-alent to that for
3(a )-3( u) are based on operation at temper­
atures below 11 0°C. This is due to the fact
thus permits loads above the rating to be safely
carried
under
continuous operation at 110
many conditions without en­
croaching upon the nonnal life expectancy of
the converted load cycle and ambient condi­
life expectancy are given in Tables 3 (a)-3( u ) .
For
conservative
use
of these
tables,
tions during a 24 h period. The 1 1 0 °C hot­
it is
test-spot temperature is based on the hottest­
D
C margin described in
spot rise of 80°C plus the standard ambient
3.5.1 be used in detennining the ambient
temperature of 30
temperature.
6.5 . 104 hours or over seven years. Actually a
transfonner operating outdoors at rated ca­
vices are supplied, when specified, which indi­
a
simulated
hottest-spot
D
D
C. At 110 C insulation
temperature, Fig 1 indicates the life would be
4.1.2.4 Loading by Hottest-Spot Temper­
ature Indicator. Hottest-spot temperature de­
cate
C hottest-sp ot
temperature as detennined from Fig 1 and the
hottest-spot temperature profile resulting from
the transformer. Suggested loadings for nonnal
suggested that the 5
0
pacity would have a much longer life because
the annual average ambient air temperature in
temperature.
These devices may be used as a guide to limit
most
locations in the US does not exceed
are calibrated for use with specific transformers
°
20°C by m ore than a few degrees. At 100 C
°
(20 DC ambient temperature plus 80 C hot­
test-spot rise), Fig 1 indicates the life would be
2
lOS hours or over 22 years. If the loading
and simulate the hottest-spot temperature by
over weekends is lighter, as is normally the
load and ambient temperature. Higher loads are
years.
loads.
Thermal relays, when supplied, indicate tem­
peratures reached in the windings. These relays
•
taking into account preceding loading, existing
permitted
for
short
periods
than
for
case, the total life could extend to over 30
long
In
periods of time because of the transfonner's
areas where the annual mean ambient
temperature
time constant.
exceeds
25°C,
the
capability
values in the tables should be reduced 1.5% for
15
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92-1981
every
IEEE GUIDE FOR LOADING M INERAL-OIL-IMMERSED POWER
degree
exceeds 20
a
the mean annual temperature
and
C. This reduction in peak loading
the
wide
range
in ratings covered are
reasons why this loading guide is made conser­
is intended to compensate for the fact that
vative in its suggested loadings. Some of the
generally higher ambient temperatures through­
variables
out
temperature between localities; differences in
the
year
temperatures,
will
for
result in higher winding
are:
wide
differences
in
ambient
any assumed annual load
elevation; restricted air circulation caused by
cycle, causing greater insulation deterioration.
buildings, fire walls, etc; previous emergency
If this correction is made, no correction of the
loading history which may not be known to
ambient temperatures shown in the table will
the operator; and variations in design character­
be necessary, and these should be the antici­
istics from those in Table 2. As a guide, an
pated values associated with the occurrence of
average loss of life of 1 % per year or 4% in any
the peak load.
one emergency operation is considered reason­
The method used to calculate Tables 3(a)-
able by some users.
3(u) is given in Section 6.
4.2.2 Methods for Determining Loads above
Rating with Some Sacrifice of Life Expectancy
4.2 Short-Time Loading with Moderate Sacri­
4.2.2.1 Transformers with Known Specific
fice of Life Expectancy
Characteristics. If the specific characteristics of
4.2.1 Aging of Insulation Due to Operation
a transformer are known and maximum recom­
above 110 °c Hottest-Spot Temperature
(1)
mended capability is required, the user may
When the aging effect of one load cycle
calculate the oil rise and hottest-spot temper­
or the cumulative aging effect of a number of
ature using either the graphic solution illus­
load cycles is greater than the aging effect of
trated in Section
continuous operation at rated load over the
same period of time, the insulation deteriorates
at
a
faster
rate
than
allowable load for his conditions by taking into
account the ambient temperature, probable
normal. The rate of
deterioration is a function of time and temper­
number of such loads during the life of the
ature and is commonly expressed as a percent­
age
loss of life.
transformer, and the approximate percentage
Charts and tables showing
of life he is willing to sacrifice.
4.2.2.2 Transformers with Unknown Spec­
percent loss of life for various combinations of
time and continuous temperature are given in
ific
Fig 3.
(2) It
should
be clearly understood that,
not known
various
conditions,
this
4.2.2.3 Assumed Characteristics for Trans­
formers which Allow the Loadings in Tables
tion is generally characterized by a reduction in
3(a)-3(u). Transformers vary widely in the
both mechanical and dielectric strength, but
characteristics
these characteristics may not necessarily be
affect
their short-time
all transformers of a given class must be based
charred condition will have sufficient strength
on characteristics which give conservative re­
to withstand normal operating electrical and
sults. The characteristics shown in Table 2 are
mechanical stresses. A transformer having insu­
considered typical of a power transformer and
lation in this condition may continue in service
are for general use.
for many months or even years if undisturbed.
4.2.2.4 Temperature and Load Limitations.
On the other hand, any unusual movement of
The following are recommended individually
such as may be caused by
limiting temperatures and loads and are used in
expansion of the conductors, due to heating
Tables 3(a)-3(u).
(1)
resulting from a heavy load or to large electro­
magnetic forces resulting from short circuit,
Maximum top-oil temperature -
(2) Maximum hottest-spot conductor
may disturb the weakened insulation such that
temperature -
turn-to-turn or layer-to-layer failure will result.
of
which
capabilities. Any general guide which applies to
directly related. In some cases, insulation in a
(3) The uncertainty
or when conservative operation
ing explicit preload conditions.
former insulation life. Deterioration of insula­
conductors
Loads.
of permitted loads of various durations follow­
information can only be an indicator of trans­
the
Conservative
bility Tables, Table 3(a)-3(u), for tabulations
estimating the relative loss of life due to loads
under
or
above rating is satisfactory, refer to the Capa­
considered to be conservative and helpful in
rating
Characteristics
When specific transformer characteristics are
while the insulation aging information used is
above
6 or the basic formulas in 6.7.
With this data, the user may determine the
1100
C
180°C
(3) Maximum short-time
service conditions
loading -
2 . rating
16
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
TRANSFORMERS UP
TO 100 MVA W ITH 55 ° C OR 65 ° c
5
ANSI/IEEE
C57.92-1981
AVERAGE W INDING R ISE
MAXIMUM PERCENT LOSS OF LIFE
65 C RISE TRANSFORMERS
"
3
....
z
w
U
0::
W
a.
,
w
...
2
:J
...
a
C/) 0.5
C/)
a
J
�
:::>
0.3
)(
'"
�
0.2
!
0.1
�----��-----H�--�4---�--+-�--�---4-
0.05 L-L-__�__-L__-LL-__-L�__-L__�-L____L-____�______�
110
120
130
150
140
170
160
HOTTEST-SPOT TEMPERATURE IN ·C
180
*Expressed as percent loss of life for one occurrence of specified
time duration for operation at temperature indicated.
Hottest-Spot Temperature in Degrees
Maximum Loss of Life (%)
Duration
Hours
0.1
1
1
2.00
4.00
0.25
0.50
161
172
180
153
163
172
2
145
155
163
172
180
4
138
147
155
163
172
180
8
131
140
147
155
163
172
24
120
129
136
143
150
158
2'
1.00
180
Fig 3
Maximum Loss of Life
-
65°C Rise Transformers
17
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92·19S1
IEEE GUIDE FOR LOADING MINERAL·OIL·IMMERSED POWER
Table 2
65 DC Rise Transformers - Assumed Characteristics at Rated Load
Effective Cooling Mode
OA
or
OW
FA
133%
or Less
FA**
over
133%
Directed
FOA or FOW
Non·Directed
FOA or FOW
Hottest·spot conductor
t emperature rise (above
D
ambient) C
80
SO
SO
SO
80
Top·oil temp erature rise
(above ambient) °c
55
50
45
45
45
Top-oil time constant, (h)
3.0
2. 0
1.25
1.25
1.25
Hottest·spot conductor time
co nstant, (h)
0.08
0.08
0.08
0.08
0.08
Ratio of load to iron losses
3.2
4.5
6.5
6.5
6.5
*m (wi nding exponent)
O.S
0.8
O.S
O.S
1.0
*n (oil exponent)
O.S
0.9
0.9
1.0
1.0
*m is the exponential power of winding loss versus winding temperature rise.
*n is the exponential power of total loss versus top·oil temperature rise.
The i nd icated values of m and n are approximate, p articularly in t he more complicated d esigns, and are subject to
further study.
**Some OA/FA/FA designs follow more closely the values for FA (133% or l ess).
4.2.2.5 Load Cycles. Transformers usually
operate on a load cycle which repeats each
24 h. This load cycle may be constant or it
may have one or more peaks during the 24 h
period. The actual load cycle may be converted
to a two-step cycle by the method given in 6.6.
Where actual average loads before the peak
load differ from those in the tabulations,
sufficient accuracy can be obtained by inter­
polation.
Index f o r Table 3
0
65 C Rise Transformers
(A Tabulation of Loads for Normal and
Moderate Loss of Life)
Following initi al load of:
Typ e of Cooling
4.2.2.6 Basis for Moderate Sacrifice of Life
Loading in Tables 3(a)-3(u). Load values in
Tables 3(a)-3(u) are based on the life expect­
ancy data shown in Fig 1, the assumed trans­
former characteristics from Table 2 and the
calculated hottest-spot temperature profile for
the daily load cycle and ambient temperature
condition that exists during the 24 h period.
The loss of life values shown in Tables 3(a)3(u) are in addition to the normal loss of life of
0.0369% per 24 h which would result from
continuous operation at rated load in a con­
stant 30 DC ambient.
5 0%
70%
90%
(c)
(c )
( d)
(d )
100%
Self·cooled (OA)
Water·cooled (OW)
Forced ·air·coole d *
(OA/FA)
(a)
(a )
(b)
(b)
(e )
(f)
(g)
(h)
Forced ·oil·cooled,
Directed flow,
( FOA, FOW,
OA/FOA/FOA**)
(i)
(j)
(k)
(I)
Forced·air·cooled**
( OA/FA/FA)
(m)
(n )
(p )
(q)
Forced-oil·cooled,
Non·directed flow,
(FOA, FOW,
OA/FOA/FOA**)
(r)
(s)
(t)
(u)
*Ratings 133% or less of self·cooled rating
**Ratings greater than 133% of self-cooled rating
18
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
>-l
Table 3(a)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Self-Cooled (OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 50% of Nameplate Rating
::c
>
z
00
"'i
0
::c
s:
=
Ambient ° c
Hours
of
Peak
Load
1
2
t-'
(J:J
2
%
R
24
s
HotSpot
30
Peak
Load
Per
n it)
HotSpot
Temp
46
2.00
131
56
2.00
141
66
60
2.00
146
70
1.95
2.00
152
156
79
80
T o pOil
Temp
HotSpot
Temp
Normal
0.25
0.50
1.00
2.00
4.00
2.00
121
Normal
0.25
0.50
1.00
2.00
4.00
2.00
136
N o rmal
0.25
0.50
1. 00
2.00
4.00
1.89
2.00
N o m al
0.25
0.50
1.00
2.00
4.00
1.63
1.82
1.89
1.95
140
154
172
191
85
99
103
108
1.54
1.73
l.80
1.87
139
163
171
180
89
102
107
112
1.45
1.65
1. 71
Normal
0.25
0.50
1.00
2.00
4.00
1.45
1.61
1.66
1.72
1.78
130
152
160
169
177
65
99
103
108
114
1.36
1.53
1.59
1.65
129
151
159
168
88
102
107
112
1.27
1.45
1.51
129
151
158
92
106
110
1.18
1.37
1.43
128
150
158
95
109
114
1.08
1.28
No rmal
0.25
0.50
1.00
2.00
4.00
1.28
1.44
1.48
1.54
1.59
1.65
113
133
140
147
155
163
76
88
93
97
102
107
1.20
1.36
1.41
1.46
1.52
1.58
113
133
140
147
154
163
79
92
96
101
106
111
1.11
1.28
1.34
1.39
1.45
1.50
113
133
140
147
154
162
83
96
100
105
109
114
1.02
1.20
1.25
1.31
1.37
113
132
139
147
1�4
87
99
103
108
113
-
0.92
1.11
1.17
1.23
J
(o
C)
(o
C)
J
t C)
Top-
Oil
Temp
(o C
)
Peak
Load
(P e r
Unit)
Tsmp
(
C)
TopOil
Temp
tC)
Peak
Load
(Per
Unit)
HotSpot
HotSpo t
Temp
o
TopOil
Te mp
Peak
Load
(Per
Unit)
2.00
151
76
1.94
2.00
156
161
1.83
2.00
151
166
85
90
1.69
2.00
149
176
( C)
i:"1
40
Peak
Load
Per
nit)
Loss
of
Life
r
4
20
10
0
(0 C )
Temp
tC)
50
Top-
Peak
Loa d
(Per
Unit)
HotSpot
Temp
85
86
1.78
2.00
155
171
92
96
91
100
1.55
1.87
1.97
148
174
183
98
106
109
TopOil
Temp
o
( C)
(o C
)
r
Oil
Tem
tc
::c
00
e:::
"tl
>-l
0
......
0
0
i:i::
<:
>
::s
>-<
>-l
::r:
""
""
0
(")
0
::c
147
159
78
84
1.79
2.00
147
169
83
94
1.69
1.92
2.00
146
171
179
138
162
170
88
100
104
93
106
III
1.57
1.82
1.90
1.98
1.34
1.56
145
170
178
187
137
162
93
105
109
112
97
111
1.45
1.72
1.80
144
169
177
98
110
114
1.31
1.60
141
168
102
114
a>
""
0
(")
>
<:
i:"1
1.23
1.47
135
161
100
115
1.11
1.36
133
159
103
118
::c
>
c;J
i:"1
::s
52
0
126
149
98
112
0.97
1.19
125
148
101
116
52
c;J
::c
u:;
i:"1
112
132
139
146
90
103
107
111
0.81
1.02
1.08
111
132
130
93
106
110
(")
"" >
:-'Z
<0 00
NOTE: Underlined values, though beyond recommended limits (see 4.2.2.4), are given to assist in interpolation of the maximum limit.
% lo s of life is in addition to normal loss of life.
*AcLUal we.ter temperature should be 5
°c
lower than the ambient temperatures shown above (see 3.5), and must be above zero
°c.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
",,>-<
, �
...........
<oi:"1
oot:<:l
...... i:"1
C'J;I>
o<Z
:"00
"' .....
to:;:;
' trl
Table 3(b)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Self-Cooled (OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 70 % of Nameplate Rating
�trl
=
Hours
of
Peak
Load
!
2
%
Loss
of
Life
Peak
Load
Per
Jnit)
HotSpot
T8 mp
( C)
Top-
Oil
Temp
(o C )
Peak
Load
(Per
Unit)
HotSpot
Temp
o
( C)
Normal
2 . 00
129
53
2.00
139
63
Normal
2 . 00
143
67
1 .98
151
77
0.25
0.50
1.00
2 .00
4.00
Normal
4
0 . 25
0.50
1.00
2.00
4.00
N o r ma l
8
0.25
0.50
1 .00
2 .00
4.00
Normal
24
Peak
Load
(Per
Unit)
0.25
0 .5 0
1 .0 0
2 .00
4.00
1 .84
2.00
166
1 64
80
88
HotSpot
T8mp
( C)
1 .8 6
2 . 00
150
163
83
87
Pe ak
Load
(Per
Un i )
t
Hot-
Spot
Temp
o
( C)
40
Peak
Load
(Per
Unit)
Temp
(Oq
Temp
TopOil
(" C )
Peak
Load
(Per
Top-
155
159
83
83
1 . 80
2.00
1 54
1 69
90
93
1 .72
2 . 00
148
173
89
97
1 . 56
1 . 91
2.00
146
1 74
183
95
1 04
1 07
85
97
98
1 .62
1 .87
1 .94
2 .0 0
144
1 70
1 77
1 84
90
102
1 05
1 08
1 . 50
1.77
1 .84
143
1 69
1 77
95
1 07
111
1 36
161
1 69
93
1 07
112
1 .30
1 .5 2
1 . 59
1 34
1 60
1 68
96
110
115
1 38
162
170
178
89
103
1 08
112
1 .4 1
1 .6 2
1.69
1 . 43
1 . 60
1 . 66
1 .71
129
152
159
167
175
84
98
103
1 08
113
1 . 31
1 .52
1 .5 8
1.63
1 28
151
1 58
166
88
102
106
111
1.25
1 .44
1 . 50
1 . 55
1 27
1 50
158
1 65
1.29
1 .44
1 .48
113
1 33
140
14 7
154
162
76
88
93
97
102
107
1 . 20
1 .3 6
1 .4 1
1 .4 6
1 .52
1 . 57
112
133
1 39
146
1 54
162
79
92
96
101
105
111
1.1 1
1 . 28
1 .33
1 . 38
1 . 45
1 .5 0
112
133
139
1 46
1 54
162
Hot-
Spot
1 . 95
2.00
146
171
174
1 .51
1 .71
1 . 77
1 .84
50
Oil
Temp
(0 C
)
1 .73
1 . 97
2 .0 0
86
99
1 03
108
113
1 . 59
1 . 64
( C)
73
139
163
170
1 79
188
1.114
TopO il
Temp
0
149
1 . 60
1.80
1 .8 5
1 . 91
1 '. 9 3
1.77
30
2.00
0 . 25
0.50
1 .0 0
2 . 00
4 . 00
Norm al
2
Top-
Oi l
Temp
(o C )
0.25
0.50
1 .0 0
2 .0 0
4 .00
�
0
Ambient Cc
20
10
0
ootr1
I-'
1. 3 6
140
167
1.65
99
111
Hot-
Top-
Unit)
Temp
(" C )
Temp
o
1 . 56
2 . 00
148
179
97
1 03
140
172
182
99
110
113
1 . 24
1.77
1 . 88
1.16
1.52
Spot
133
1 65
Oil
( C)
101
116
.....
trl
trl
trl
Q
c::
a
trl
"l
1 .1 7
1 .42
131
158
99
1 14
1.02
1.31
127
1 56
101
117
0
::0
t""
0
;I>
tJ
.....
Z
Q
�
91
105
1 10
.l1.Q.
83
96
99
1 04
109
1 14
1.16
1 .3 5
1.41
1.02
1 . 20
1 . 25
1.30
1.37
1 26
149
1 57
112
1 32
139
1 46
1 54
94
1 08
113
86
99
103
1 07
113
1.05
1 24
1 48
1.27
97
112
0.91
1.16
119
1 46
98
115
Z
trl
::0
;I>
t""
111
0 . 91
1.1 1
1.16
1 . 23
132
1 38
146
89
1 03
1 07
111
NOTE : Underlined values, though beyond recommended limits (see 4.2.2 .4), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
*Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3 . 5), and must be above zero C.
°
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.80
1 . 02
1.07
110
132
138
93
1 06
110
6
r
�
�
trl
::0
00
trl
tJ
�
0
:;:;
t::rJ
::0
Table 3(c)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° c Rise, Self-Cooled ( OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 90 % of Nameplate Rating
>-3
::0
>
Z
rn
"Zj
0
::0
=
is:
Ambient ° c
a
Hours
of
Peak
Loa d
%
Loss
of
Life
Normal
1
2
0.25
0.50
1 .00
2 . 00
4.00
Normal
0.25
0 . 50
1 . 00
2 . 00
4.00
t>:l
Normal
I-"
0.25
2
0 . 50
Pea k HotSpot
Lo a d
�Per T(�mp
C)
nit)
2.00
2 .0 0
1 .77
2.00
1 39
151
145
170
TopOil
Temp
eC)
63
75
83
94
1 . 00
2.00
Peak HotSpot
Load
(Pcr Temp
Unit)
2.00
1 . 87
2.00
1 . 65
1 . 90
1 . 97
2.00
eC)
149
149
161
143
169
177
180
TopOil
Temp
eC)
73
81
85
87
99
103
104
Peak HotSpot
Load
(Per T(�mr
Unit)
1.94
2 .0 0
1.72
2.00
1.52
1 .7 9
1 .8 7
1 .95
C
154
1 59
Toy-
Oi
Temp
(0 C )
82
83
147
171
87
95
91
1 04
1 08
112
1 40
1 67
175
185
40
30
20
10
Pe k
Lo d
a
a
(Per
Unit)
1.73
2 .0 0
1.53
1 .91
2 .00
1 .34
1 . 67
1 .76
Hot-
Spot
Temp
tCl
1 49
1 69
142
173
181
1 34
165
174
Toy-
Oi
T�mp
( C)
89
93
92
102
105
94
108
112
Peak
Load
(Per
Unit)
1.00
1 . 98
Hot-
Spot
Te m p
(0 C
)
115
2 .0 0
1 77
1 79
1 .0 0
1 .76
1 .8 8
180
0 .94
1 .54
115
170
112
162
l"l
::0
rn
50
TopOil
Temp
(o C)
90
103
103
90
1 08
111
90
112
Peak
Load
(Per
Unit)
HotSpot
Temp
(o C )
TopOil
Temp
( oC
)
1.78
1 .94
17 2
184
110
112
-
1 . 56
164
113
0 .25
4
0.50
1 . 00
2 . 00
4 . 00
Normal
8
0.25
0 . 50
1 . 00
2 . 00
4 . 00
Normal
0 .2 5
0 . 50
24
1 . 00
2 . 00
4 . 00
1 .5 6
1 .7 6
1.82
1 .8 8
1 .95
1 78
187
1 .4 1
1 . 59
1 .64
1.70
1.76
127
1 50
158
166
175
1 . 27
1 .4 3
1 .4 8
1 . 53
1 .59
1 .64
137
161
1 69
112
132
139
146
1 54
162
89
1 04
86
100
104
109
114
1 . 46
1 . 67
1. 73
1 . 80
135
160
168
176
84
1 .32
1 . 51
1 . 56
1 .62
126
150
157
165
III
1 .1 9
1 . 36
1.41
1 . 46
1 .52
1.57
112
132
92
98
103
107
113
7 .5
88
92
97
10 2
107
1 39
146
154
162
108
112
87
101
106
79
96
101
105
110
1 .34
1 .5 8
1.64
132
1 59
167
92
1 07
111
is:
<:
>
:a
......
>-3
::r:
'"
'"
°
0
::0
0>
'"
1.36
156
115
°
(".)
>
<:
l"l
1 . 20
1 .47
1.. 5 5
128
1 56
165
94
110
115
0. 9 4
1.36
1 13
1 54
90
ill
1 . 20
1 -1 8
114
::0
>
CJ
l"l
::s
Z
tJ
1.22
1 .4 2
1 .48
1 .5 4
1.10
1 .27
1.33
1 .38
1 .4 4
1 .5 0
1 24
148
1 56
164
89
1 04
1 09
1 14
111
132
82
95
99
139
146
153
162
1 04
1 08
114
1 .1 0
1.33
1 .3 9
1 20
147
1 54
91
107
112
0 .9 1
1.23
1 .0 1
1 .1 9
1 . 24
1 .3 0
1 .3 6
111
131
138
146
153
86
98
103
107
112
0. 9 1
1.10
1.16
1.22
110
144
89
110
Z
1.10
140
111
CJ
::0
......
00
l"l
1 10
131
138
145
89
1 02
1 06
111
v
NOTE : Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ), are gi en to assist in interpolation of the maximum limit.
% l o of life is in addition to normal loss of life.
*Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5), and must be above zero D C .
ss
.....
0
0
(".)
4.00
Normal
e::
't)
>-3
0
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.79
1 .01
1.06
1.13
1 09
13 1
137
145
92
1 06
109
114
(".)
"' >
:-' Z
"' 00
�
......
, �
..... ......
", l"l
oo l"l
..... l"l
(') :>
O1 Z
:-' 00
00 ....
� ;::;
Table 3(d)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Self-Cooled (OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 1 00% of Nameplate Rating
�
�
oo trJ
=
0
Hours
of
Peak
Load
!
2
%
Loss
of
Life
Peak
Load
Per
nit)
Normal
2 .00
0 .25
0 . 50
l .00
2.00
4 .0 0
Normal
2
0.25
0 .50
1.00
2.00
4.00
Normal
4
0.25
0 . 50
1 . 00
2 .00
4.00
Normal
8
0 . 25
0 . 50
1 .00
2.00
4 .00
Normal
24
20
HotSpot
T �mp
TopOil
Temp
Peak
Load
Per
nit)
HotSpot
Temp
TopOil
T �mp
144
68
2.00
1 54
78
( e)
te)
J
te)
( C)
0.25
0.50
1 . 00
2.00
4 .00
Normal
�
�
J
Ambient ° e
10
0 . 25
0.50
1 .0 0
2.00
4 .00
1 .93
2 . 00
149
156
78
80
l .78
2 .00
14 6
1 66
83
90
�
HotSpot
T�mp
T O'
Te lIP
J 80
:" . 0 0
1 49
1 64
a5
1 . 59
1 .97
2.00
1 41
173
176
88
99
1 00
Peak
Load
(Per
Unit)
( e)
tC)
88
30
50
40
r
HotSpot
T�mp
TopOil
T�mp
Peak
Load
Per
nit)
HotSpot
T 8mp
To Oi
Temp
l .8 4
2 . 00
172
184
1 06
1 08
l .00
1 .7 2
130
173
1 05
1 14
164
175
1 09
1 13
1 . 00
1.50
138
164
105
1 16
Peak
Load
( Per
Unit)
HotSpot
T�mp
l . 00
2.00
1 10
1 74
85
98
1 . 00
1 .8 1
1 .93
2 . 00
110
1 69
179
186
85
104
108
110
1 .63
1.77
1 .4 4
( C)
1 .71
1 . 95
2 .00
142
1 68
173
83
95
98
l .59
l .8 5
1 .93
2.00
140
167
176
1 83
88
100
104
108
1 .4 2
1 .7 3
1 .8 2
1 .9 1
1 35
1 65
1 74
1 83
91
1 04
1 09
113
1 .00
1 .6 1
1 . 70
1 10
162
172
85
109
113
1 .5 3
1 .7 3
1 .80
l .8 6
1 .9 3
135
160
168
176
186
86
100
104
109
1 14
1.42
1 .64
1 .7 1
1 .7 8
133
1 58
167
176
89
103
lOS
113
1 .28
1 .5 5
1 .6 2
1 27
157
165
90
1 07
111
1 .00
1 .4 3
1 .5 2
1 10
153
163
85
1 09
115
1 .40
1 . 58
1 . 63
1 .69
1 . 75
126
1 50
1 57
165
173
83
98
1 02
107
112
1 . 30
1 . 49
1 .55
1 .6 1
1 .6 7
1 24
148
1 55
164
173
86
1 01
105
1 10
116
1.19
1 .4 1
1 .46
1 . 53
1 20
147
1 54
1 63
104
108
1H
l .00
1 .3 0
1 .3 8
110
144
1 53
1 .27
1 .43
1 .48
1 .53
1 . 59
1 .64
112
132
139
146
1 54
162
75
88
92
97
1 02
107
1.19
1 .35
1 .4 1
1 .4 6
1 .52
1 . 57
111
132
1 39
146
154
1 62
78
91
96
100
105
110
1 . 09
1 . 27
1 . 32
1 .38
1 .44
1 . 50
1 10
1 32
1 38
146
1 53
161
81
95
99
1 04
1 08
114
�
Peak
Load
Per
nit)
To Oi
T�mp
( e)
>-'
�
( C)
156
( e)
111
�
l .0 0
l . 34
( e)
130
1 58
(0C)
1 05
1 17
....
trJ
trJ
trJ
0
c:
....
tl
trJ
"'J
0
::0
t"
1 .28
1 . 39
147
1 59
110
117
1 . 00
1 .22
1 30
151
1 05
117
0
:>
tl
....
Z
0
�
8 :7
1 . 00
1 .19
1 . 24
1 . 30
1 .36
110
13 1
1 38
145
1 53
85
1 06
III
85
98
103
107
112
Z
1 .1 9
1 . 27
140
149
107
113
1 . 00
1.13
1 30
143
105
113
trJ
::0
:>
t"
6
....
0 .89
1 . 09
1 . 16
1 . 22
1 09
130
1 38
145
88
101
1 06
111
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ), are given to assist in interpolation of the maximum Iimit_
% loss of life is in addition to normal loss of life.
*Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3 . 5 ), and must be above zero ° e_
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.77
1 . 00
1 .06
1.13
1 08
130
1 37
144
91
1 05
1 09
1 14
t"
....
�
�
trJ
::0
00
trJ
tl
"0
0
::;;
trJ
::0
>"I
�
>
Z
00
"%J
0
�
Table 3(e)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Air-Cooled (OA/FA) Transformers Rated 133% or Less of Self-Cooled Rating
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
=
s::
t<l
Ambient ° c
0
Hours
of
P ak
Load
e
1
2
%
Loss
of
Li f
e
Normal
t-:)
C<:>
0 . 25
0.50
1 .00
2 . 00
4 . 00
Normal
2
0.25
0.50
1 . 00
2.00
4 . 00
N ormal
4
0.25
0.50
1 .00
2.00
4 . 00
Normal
8
0.25
0 . 50
1 .00
2.00
4.00
Normal
24
H t-
o
Spot
�Per
T�m p
nit)
Load
( C)
2.00
140
( C)
Pea k
Load
(Per
HotSpot
Temp
0
50
2 .00
150
Topl
Oi
Temp
o
Unit)
( C
)
TopOil
T�mp
(
C)
60
0.25
0.50
1 .00
2.00
4 .00
Normal
1
Peak
20
10
0.25
0.50
1 . 00
2 .00
4 . 00
y
30
Peak
Load
(Per
Unit)
HotSpot
T�mp
(
1 .9 7
2.00
1 58
1 60
69
70
1 .8 7
2.13
1 57
184
1.74
1 .9 5
2.02
153
1 78
1 86
80
90
94
1 .6 4
1 .8 7
1 .9 4
152
178
186
C)
To Oi
T� mp
( e)
Peak
Load
Per
nit)
�
HotSpot
y
40
50
HotTopOil
Spot
(Per Temp Temp
(0
Peak
Load
HotSpot
TopOil
Peak
Load
Unit)
C)
C)
Unit)
(C)
C)
76
84
1 .76
2.02
157
183
83
90
1 .63
1 .9 2
156
182
90
97
85
96
99
1 .54
1.77
1 .8 4
1 50
176
185
91
101
105
1 .4 2
1 .6 7
1.75
149
175
184
96
107
110
To Oi
Temp T�mp
( e)
e)
t
(Per Temp
Temp
(o
(0
�
00
e::
"t:I
>"I
0
....
0
0
s::
<:
>
::;;
=3
1 .93
2.1 2
154
179
69
79
1 .8 3
2.04
153
178
74
84
!:I:
01
01
0
C':l
0
�
1 . 68
1 . 85
1 . 90
148
172
180
79
92
96
1 . 59
1 .77
1 .83
1 . 89
146
171
179
188
83
96
100
105
1.51
1 .70
1 .76
1 .82
146
170
179
188
88
1 00
1 05
1 09
1 .4 2
1 .62
1 . 68
1.75
145
170
178
187
92
105
109
114
1.33
1.53
1 .6 0
144
169
177
96
109
1 13
1 .22
1 .4 5
1 .4 8
1 . 63
1 . 68
1.73
1 .78
1 38
162
170
178
187
82
96
101
106
111
1 .4 1
1.57
1.61
1 .66
1 . 72
138
162
1 69
177
1 86
86
1 00
104
109
115
1 .33
1 .4 9
1.55
1 . 60
1 37
1 60
1 68
177
89
103
1 08
1 13
1 .25
1 .42
1.47
136
159
167
93
1 07
112
1.16
1 .3 4
135
1 59
97
1 .0 7
1 . 26
1 .35
1.49
1 . 54
1 . 59
1 . 63
1 . 68
127
149
156
164
172
181
78
92
96
101
106
112
1 . 28
1.43
1 .4 8
1 .52
1 . 58
126
148
1 56
163
172
82
95
100
104
110
1 .2 1
1 . 36
1 .41
1 .4 6
1 .5 1
1 26
1 48
155
1 63
171
85
99
103
108
113
1.13
1 . 29
1 .3 4
1 . 39
1 25
148
155
1 63
89
103
107
112
1 .05
1.21
1 .27
1 25
147
1 54
92
106
111
0.95
1.14
1.19
1 24
146
1 54
96
1 09
1 14
1 . 24
1 . 38
1 .4 2
1 .4 6
1 .51
1 .55
112
131
138
145
153
160
69
81
85
90
95
99
1.17
1 .3 1
1.35
1 .4 0
1 .4 5
1 .4 9
111
131
1 38
145
153
160
73
85
89
94
98
103
1 .09
1.24
1 .2 9
1 .3 3
1 .3 8
1 .43
111
131
1 38
145
152
160
76
89
93
97
102
1 07
1.01
1.17
1 . 22
1 .2 7
1 .3 2
1 .3 7
111
131
1 38
145
152
160
80
93
97
101
106
111
0.92
1 .0 9
1.14
1.19
1 .25
111
131
1 38
145
1 52
84
96
100
105
110
0.83
1 .0 1
1 .0 6
1.12
1.17
110
131
1 37
144
152
88
1 00
1 04
1 09
113
III
142
1 68
1 00
114
'"
01
0
C':l
�t<l
133
1 58
100
114
�
>
0
l"l
::;;
Z
NOTE: Underlined values, though beyond recommended limits (see 4.2.2. 4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
a
H
Z
0
�
H
00
l"l
C':l
01 >
:-' Z
10 00
H
Nl
, .... ....
1O l"l
oo l"l
.... l'l
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0>
O1 Z
:-'1 00
co ......
1:>:1 ;::;
' ttl
Table 3(f)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Air-Cooled (OA/FA) Transformers Rated 133% or Less of Self-Cooled Rating
Equivalent Load Before Peak Load 70% of Maximum Nameplate Rating
� ttl
00 ttl
....
=
Hours
of
Peak
Load
1
2
%
Loss
of
Life
24
HotSpot
Temp
0
( C
)
TopOil
Temp
(o
C)
Peak
Load
(Per
Un it )
HotSpot
T(li mp
y
To Oi
Tli mp
(
C)
Peak
Load
(Per
U n it )
HotSpot
Temp
(0
To Oi
Tgmp
r
Peak
Load
(Per
( C)
Unit)
57
2.00
158
67
1 .89
2.15
1 58
183
74
82
1 . 78
2 . 04
1 56
182
81
88
1.65
1.94
Normal
1 .87
2 . 07
153
178
72
82
1 .7 7
1 .9 9
2 .06
152
178
186
77
88
91
1 .6 7
1 .90
1 .9 7
151
177
185
-
82
93
97
1.57
1.81
1 .8 8
150
176
1 84
-
88
99
102
( C
)
0 .25
0 .50
1 .00
2.00
4 .00
0.25
0 . 50
1 .00
2 .00
4 . 00
0.25
0 . 50
1 . 00
2 . 00
4 . 00
Normal
8
( C
)
Peak
Load
(Per
U n it )
148
Normal
4
Top·
Oil
Temp
a
40
2.00
Normal
2
r
.crni t )
HotSpot
T!i mp
30
Normal
0 . 25
0 .50
1 .00
2 . 00
4 .00
t>:l
..,.
Peak
Load
Ambient °c
20
10
0
C)
1 45
1. 71
1 .7 9
Spot
Temp
(o
C)
50
TopOil
Temp
(o
C)
1 55
182
88
96
148
1 75
184
93
1 04
1 08
Peak
Load
(Per
Unit)
Hot-
Spot
t C)
Temp
Top Oil
Temp
(C )
1 .49
1.83
151
181
94
102
1 . 30
143
173
181
98
1 09
1 13
1 . 60
1 . 68
......
ttl
ttl
ttl
Q
c::
1 .64
1 .8 2
1 .88
l .9 3
1 47
171
179
188
80
93
97
1 02
1 . 56
1 .74
1 .80
1 . 86
1 .4 6
1 .6 2
1 .67
1 .7 2
1 . 77
137
161
169
177
186
82
96
101
106
111
1 . 39
1 .35
1 26
1 48
155
163
171
180
0 . 25
0 . 50
l .00
2 .00
4 .00
1 . 49
1 . 53
1 . 58
1 . 63
1 . 68
N ormal
1 . 24
l . 37
1 .4 1
1 .4 6
1 . 50
1 . 55
0.25
0 . 50
1 . 00
2.00
4 .00
C)
HoL-
III
131
1 37
145
152
1 60
1 45
170
179
187
84
97
1 02
106
1 .4 7
1 . 66
1 .7 2
1 .79
144
1 69
177
186
89
1 01
1 06
110
1 .37
1 .58
1 .64
1 . 60
1 . 65
85
1 00
104
110
1.31
1 .48
1.53
1 .59
1 35
1 59
1 67
1 76
89
103
1 08
1 13
1 .22
1 .4 0
1 .4 6
78
91
96
101
106
111
1 . 28
1 .43
1 . 47
1 . 52
1.57
1 .62
125
1 48
155
163
171
180
81
95
99
104
109
1 .2 0
1.35
1 .4 0
1 .45
1 . 50
1 25
147
1 54
1 62
1 70
85
98
103
1 08
113
1 .12
1 . 28
1.33
1 .38
69
81
85
90
94
99
1.17
1 . 30
1 . 35
1 .4 0
1.45
1 .50
73
85
89
94
98
103
1 . 09
111
1 31
1 37
1 45
1 52
1 60
76
89
93
97
102
1 07
1 . 01
1.17
III
131
1 38
145
152
1 61
lli
1 . 24
1 . 28
1 . 33
1.38
1.43
92
1 06
110
1.27
1.49
1 40
1 67
96
110
1 . 14
140
1 36
165
99
1 14
a
ttl
"<J
0
!:d
t""
136
160
168
177
1.55
142
1 68
176
1 34
1 58
166
92
1 07
III
1.13
1 .32
132
157
96
110
1 .0 1
1 .23
1 29
155
98
1 13
0
>
0
Z
Q
s:::
Z
1 .21
1 . 26
1 .3 1
1 . 37
1 24
147
153
162
110
1 31
137
144
152
160
88
1 02
106
ill
80
93
97
101
100
111
1.03
1.21
1 . 26
1 23
146
153
91
105
110
0.92
1.12
1.18
1 20
145
152
94
109
113
t'l
!:d
>
t;"'
0
......
t'"
,!..,
0.92
1 .0 9
1.14
1.19
1 . 24
1 . 30
111
1 30
1 37
1 44
152
160
84
96
100
1 04
1 09
114
NOTE: Underlined values, though beyond recommended limits (see 4.2.2.4), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.83
1 .00
1 .06
1.12
1 .17
110
1 30
136
144
152
88
1 00
1 04
108
1 13
s:::
s:::
t'l
!:d
tn
t'l
0
"tI
0
:;J
ttl
!:d
0-3
::>:I
>
2
00
"'J
0
::>:I
Table 3(g)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° c Rise, Forced-Air-Cooled (OAjFA) Transformers Rated 133% or Less of Self-Cooled Rating
E quivalent Load Before Peak Load 90% of Maximum Nameplate Rating
=
s::
Ambient ° c
Hours
of
Peak
Load
%
Loss
of
Life
Normal
!
2
0.25
0.50
1 . 00
2.00
4.00
Normal
1
�
0.25
0.50
1.00
2.00
4.00
Normal
01
2
0 . 25
0.50
1.00
2.00
4.00
Normal
4
0.25
0.50
1 . 00
2.00
4.00
Normal
8
0.25
0.50
1.00
2.00
4.00
Normal
24
0.25
0.50
0.00
2 . 00
4.00
Peak
Load
Per
nit)
J
2.00
l . 79
2.01
1 . 59
1 . 78
1.83
1.90
Hot·
Spot
T�mp
( C)
1 57
1 51
177
144
1 69
177
1 87
Top·
Oil
Temp
( C)
67
75
86
81
94
98
103
Peak
Load
(Per
Unit)
Spot
Temp
(0
80
88
1.61
1 . 94
150
181
86
95
l . 23
l .81
1 .9 1
1 30
178
188
-
148
174
183
-
86
96
100
1.43
l. 72
l . 80
143
173
182
-
90
102
1 06
l . 10
1 . 60
1 . 69
1 23
171
180
140
167
175
184
89
103
107
1 . 28
1.53
1 . 59
1 36
166
174
91
107
111
1.03
1 .42
1 20
163
Peak
Load
(Per
Unit)
Hot·
Spot
T�mp
1 .88
2.15
--
1 56
183
73
81
l .76
2.04
--
1 54
�
1 .69
1.91
1.98
1 50
176
1 84
81
91
95
l . 57
l.81
l . 89
1.50
1.70
1.76
1.82
142
1 69
177
186
85
99
103
1 08
1 . 40
1 . 62
1.67
1.74
t C)
( C)
40
To Oir
T�mp
TopOil
T�mp
J
30
Hot·
Spot
T� mp
Hot·
Spot
Tem p
Peak
Load
Per
nit)
trJ
20
10
0
( C)
To
Oi
Temp
(o
Peak
Load
per
ni t )
r
e)
.!l1
J
( e
)
( e)
Hot·
C)
50
Top·
Oil
Temp
C C)
Peak
Load
(Per
Unit)
Hot·
Top-
Temp
(0
Temp
o
Sp o t
C)
Oil
( e)
88
101
104
l . 64
1 . 77
173
185
107
1
10
--
88
1 07
l . 45
165
111
1 11
-
88
110
::>:I
00
e:::
'"
0-3
0
f-'
0
0
s::
<:
>
::;::
......
0-3
:I:
01
01
°
0
0
::>:I
0'>
1.30
1 58
112
01
0
0
>
<:
trJ
::>:I
>
(,')
1 .44
1 . 60
1 . 64
1.70
1.75
1 36
159
1 67
176
184
82
96
100
105
111
1.36
1.53
1.58
1.63
1.69
1 34
1 58
1 66
175
1 84
85
99
1 04
1 09
115
1 . 27
1 . 45
1 . 50
l . 56
1 32
1 57
165
174
88
103
107
113
1.16
1 . 37
l.43
1.33
1.48
1.52
1 . 57
1.62
1.67
1 24
147
1 54
162
170
179
77
91
95
100
1 05
111
1.26
1.42
1.46
1.51
1.56
1.61
1 24
147
154
162
170
179
80
95
99
104
109
114
1 . 18
1 . 34
1 . 39
1 . 44
1 . 49
122
146
153
161
169
83
98
102
107
112
1 . 08
1 . 27
1.32
1.37
119
145
152
1 60
85
101
1 06
111
0.93
1 . 18
1 . 24
1 . 30
111
143
151
159
85
1 04
1 09
114
1 .09
1.16
140
149
106
112
t:l
......
2
(,')
::>:I
......
1 . 24
1.37
1.41
1 . 46
1.51
1.55
111
131
137
144
152
1 60
69
81
85
89
94
99
1.16
1.31
1.35
1 .40
1 . 44
1 . 49
110
1 31
1 37
145
1 52
1 60
72
85
89
93
98
103
1 . 08
1 . 24
1 . 28
1.33
1 . 38
1.43
110
131
137
145
152
159
76
88
92
97
102
106
1 . 00
1.16
1.21
1.26
1.31
1 . 36
110
130
1 37
144
151
1 59
80
92
96
101
1 05
110
0.92
1.08
1.13
1 .18
1 . 24
1 .29
1 10
1 30
1 36
143
152
1 59
84
96
100
104
109
114
1 . 00
1.05
1.11
1.17
1 30
1 36
143
151
100
1 04
108
113
0
128
1 56
1 63
90
1 06
110
0.97
1 .28
1.34
115
1 53
162
86
108
113
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
1.17
148
110
trJ
::;::
Z
00
trJ
"' >
:-> 2
<0 00
I>J ......
� "j::;j
<o trJ
oo trJ
.... trJ
0>
cn z
:-' 00
"' .....
"" -;::;
Table 3(h)
Capability Table for Normal and M oderate Sacrifice of Life
65 DC Rise, Forced-Air-Cooled (OA/F A) Transformers Rated 1 33% or Less of Self-Cooled Rating
Equivalent Load Before Peak Load 100% of Maximum Nameplate Rating
,:.. �
�
t;:j
.....
=
0
Hours
of
Peak
Load
%
Loss
of
Life
N or mal
!
2
0.25
0.50
1.00
2.00
4.00
Normal
0.25
0.50
1 . 00
2.00
4 . 00
t-:)
al
Normal
2
0.25
0.50
1.00
2.00
4.00
N o rm al
4
0.25
0.50
1 . 00
2.00
4.00
Normal
8
0.25
0.50
1 . 00
2.00
4 . 00
Normal
24
0.25
0.50
1 . 00
2.00
4 . 00
Ambient ° c
20
10
r
r
Peak
Load
(Per
Unit)
Peak
Load
Per
nit)
HotSpot
Tg mp
To Oi
Tg mp
77
85
1 . 64
1 .98
149
181
83
92
1 . 06
1 .8 4
1.95
114
178
188
147
175
183
82
93
96
1 . 47
1 . 76
1 . 84
141
173
182
86
98
102
1 . 03
1 . 65
1.73
1 .82
112
170
179
189
80
103
107
111
1.46
1 .66
1.73
1 . 79
140
166
176
184
85
99
103
1 08
1.33
1.57
1 . 65
1 .71
1 34
164
174
183
87
102
107
112
1 . 03
1 . 48
1 .5 5
112
162
171
81
95
1 00
105
111
1 . 34
1.51
1 . 56
1 . 62
1 . 68
132
1 57
165
174
183
84
99
1 04
1 09
114
1 . 23
1 .4 3
1 . 49
1.55
127
155
163
172
85
1 02
107
112
--
1 . 02
1.34
1.41
111
1 53
161
76
91
95
100
105
122
145
153
161
170
178
79
94
99
1 03
1 09
1.16
1 .31
1 . 38
1 . 44
1 . 49
119
145
152
161
169
ill
1.25
1.41
1 .46
1.50
1 . 56
1.61
1 .01
1 . 25
1.31
1.36
1.42
110
142
151
159
168
l!1..
82
97
1 02
107
112
-
80
99
105
1 09
115
--
68
81
85
89
94
99
1 .16
1.30
1.35
1.40
1 . 44
1 .49
110
131
137
144
152
1 60
72
85
89
9 :,
98
1 03
1.08
1 .23
1.28
1.33
1 . 38
1 . 43
110
1 30
137
144
1 52
159
76
88
93
97
1 02
106
1.00
1.16
1.20
1 .26
1 .:1 1
1.36
1 10
1 30
1 36
144
151
1 59
80
92
96
1 00
105
110
HotSpot
Ts mp
( C)
HotSpot
Temp
TO Oi
Temp
1 .9 3
2.19
156
183
70
78
1 . 80
2.08
1 54
1 82
1.73
1 . 96
2.03
149
176
184
77
88
91
1.63
1 . 87
1.93
1.55
1.75
1 .8 1
1 . 87
142
168
177
186
81
95
99
1 04
1 . 42
1 . 58
1 . 63
1 . 6R
1 . 74
1 34
158
1 66
1 74
184
1 . 33
1 . 48
1.52
1 . 57
1.62
1.67
124
147
154
162
170
179
1.23
1 . 37
1.41
1 . 46
1.51
1 .55
110
131
1 37
144
152
160
( C)
r
40
To Oi
Temp
Peak
Load
Per
nit)
J
30
HotSpo t
Tsmp
TopOil
Ts mp
Peak
Load
Per
nit)
J
(DC)
t C)
( C)
(oC)
J
( C)
50
Peak
Load
(Per
Uni t)
HotSpot
Tsmp
TopOil
Temp
103
107
1 . 02
1 . 59
131
175
100
111
164
175
107
111
1 . 02
1.41
131
165
1 00
113
1 . 34
1.44
1 56
1 67
108
114
1 . 01
1 . 28
130
159
100
114
1 . 23
1.31
148
158
1 06
112
1 .00
1.17
130
150
100
111
( C)
Peak
Load
(Per
Uni t)
HotSpot
Tg mp
TopOil
Temp
81
98
101
1 . 67
1 .81
172
1 84
1 . 50
1 .61
81
1 06
111
81
104
110
( C)
(DC)
( C)
(oC)
.....
t;:j
t;:j
t;:j
C')
c:::
.....
t;
t;:j
'"<J
0
:;d
t"'
0
>
t;
Z
C')
s::
Z
t;:j
:;d
1.16
1 .2 2
1 . 29
L OR
1.13
1 . 18
1 . 24
1 . 29
1 39
148
1 58
1 28
1 36
143
151
159
102
107
113
'l5
1 00
1 04
1 09
1 14
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.99
1.11
1 . 20
1 . 00
1.05
1.11
1 . 16
1 30
1 43
155
1 30
135
143
151
100
108
115
100
103
108
112
>
�.....
t"'
,.:...
s::
s::
t;:j
:;d
00
t;:j
t;
."
0
�
t;:j
:;d
"":l
::0
Table 3(i)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Oil-Cooled ( Directed Flow - FOA, FOA*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
>
z
00
"%j
0
::0
=
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
!
2
0 . 25
0.50
1 . 00
2.00
4 . 00
Normal
0.25
0.50
1 .0 0
2.00
4 . 00
t.:>
-l
2
4
8
24
r
Peak
Hot-
To -
T� mp
( C)
Temp
(0
Load
Per
nit)
Temp
(o
C)
Spot
Oi
Temp
tC)
Peak
Load
(Per
Unit)
T(�mp
C)
1.76
1.91
160
186
-
52
59
1.70
1.84
160
185
59
66
1 .6 3
1 . 79
159
185
/l
Oi
C)
J
Hot-
trl
20
Peak
Load
er
nit)
Spot
s::
Ambient °c
10
r
To -
HotSpot
40
30
r
To -
Oi
T!l mp
( C)
66
74
r
Hot-
To -
Jnit)
T( 0emp
C)
Tgmp
Oi
( C)
(Per
Unit)
1.56
1.73
159
185
74
81
1.48
1 .66
Peak
Load
per
Spot
Hot-
Peak
Load
Spot
Te mp
tC)
1 58
1M
50
T op Oil
t c)
Peak
Load
(Per
Unit)
81
88
1.41
1 . 59
Temp
Hot-
Spot
Temp
t el
157
�
TopOil
( C)
"":l
0
88
95
s::
Temp
o
'1:1
>-'
0
0
<:
>
�
1.59
1.73
1.77
1 54
179
187
65
74
78
1 .5 4
1 .67
1.72
1 53
1 78
1 87
71
80
84
1 .4 7
1.62
1.66
152
178
186
::3
77
87
90
1 .4 1
1.55
1 . 60
152
177
185
83
92
95
1 . 34
1.49
1.54
151
1 76
1 85
89
98
102
1 .26
1.43
1.48
150
176
184
94
1 04
107
Normal
0.25
0.50
1 .00
2 . 00
4 . 00
1 .45
1.57
1.61
1 .64
146
170
178
187
73
84
88
92
1 .3 9
1.52
1.55
1 .6 0
146
170
178
187
78
89
93
97
1 . 3 .1
1 .4 6
1 . 50
1 .55
145
1 69
177
1 86
83
94
98
102
1 .27
1.41
1 .4 5
1 .49
144
1 69
176
185
88
1 00
103
107
1 . 20
1 . 34
1 .39
1 . 44
143
1 67
176
185
93
1 04
108
112
1 .13
1 . 28
1 . 33
Normal
1.34
1.45
1.48
1 .52
1.56
136
158
166
174
183
73
85
89
93
98
1 . 28
1 .4 0
1.43
1.47
1.52
135
1 58
1 65
173
183
78
90
93
98
1 02
1 .22
1 .34
1 .38
1 . 42
82
94
98
102
1 07
1.16
1 . 29
1.33
1.37
1.41
1 34
157
164
173
181
87
99
102
107
III
1 . 09
1 . 23
1 . 27
1 .32
1 33
1 57
1 64
173
91
1 03
107
ill
1 . 02
1 . 17
1 . 21
l .46
135
157
165
173
182
Normal
0.25
0.50
1 . 00
2.00
4 .00
1 . 27
1.38
1.41
1.45
1 . 48
1.52
1 24
146
153
160
169
178
68
80
83
87
92
95
1 . 21
1.32
1.36
1.40
1.44
1.48
1 24
146
153
161
1 69
177
73
84
88
92
96
101
1.15
1.27
1. 31
1 . 35
1 . 39
1 .43
1 24
145
153
160
1 68
177
77
89
93
97
101
106
1 . 09
1 .21
1 . 25
1 . 29
1 . 34
1 . 38
123
145
152
160
168
177
82
93
97
101
1 06
110
1 . 02
1 .1 6
1 .20
1 . 24
1 . 28
1 23
1 45
152
1 59
167
87
98
1 02
1 06
110
0.95
1 . 09
1.14
1.18
1 . 23
1 23
144
152
159
167
91
103
106
110
115
Norm al
0.25
0.50
1 . 00
2.00
4 . 00
1.19
1 . 30
1.33
1.37
1 .4 1
1 . 44
111
131
137
144
152
160
61
72
75
79
83
87
1.13
1.25
1 . 28
1.32
1.36
1 .39
111
131
137
144
152
160
66
77
80
84
88
92
1 . 07
1.19
1 . 23
1 . 27
1.30
1 . 34
71
81
85
86
92
96
1 .01
1.13
1.17
1 .2 1
1 .2 5
1.29
111
131
1 38
145
152
1 60
76
86
90
93
97
101
0.94
1 .07
1.11
1.15
1 . 20
1 . 24
111
131
1 37
144
152
159
80
91
94
98
1 02
1 06
0.86
1 .00
1.05
1 .09
1 . 14
1.18
111
131
137
145
152
160
85
95
99
1 03
106
0.25
0.50
1.00
2.00
4.00
::0
00
�
III
131
1 37
1 45
1 52
160
142
167
175
97
1 09
ll3
:x:
<:11
<:11
0
()
0
::0
a>
C1T
0
()
>
<:
trl
1 32
156
163
96
1 08
112
::0
>
0
trl
�
-
Z
0
-
NOTE : Underlined values, though beyond recommended limits (see 4 . 2 . 2.4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
* Actual water temperature should be 5 ° c lower than the ambient temperatures shown above (see 3.5), and must be above zero C.
°
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
!!!
Z
0
::0
00
trl
()
<:11 >
;-'l Z
.0 00
t..:l . ..... -
tO trl
oo trl
..... trl
n>
O1 Z
Table 3(j)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Oil-Cooled (Directed Flow - FOA, FOW * , and OA/FOA/FOA) Transformers
E quivalent Load Before Peak Load 70% of Maximum Nameplate Rating
:--' 00
.., .....
N) "j::;
�
g]
oo trl
=
,...
Ambient ° c
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
!
2
0.25
0.50
1 .0 0
2 .0 0
4 .0 0
Normal
1
t-.:>
0.25
0.50
1 .00
2.00
4.00
Normal
00
2
0.25
0.50
1.00
2.00
4.00
Normal
4
0.25
0.50
l.00
2.00
4.00
Normal
8
0. 2 5
0.50
1 .00
2.00
4.00
Normal
24
0.25
0.50
1 .0 0
2.00
4.00
Peak
Load
�Per
nit)
HotSpot
T�mp
( C)
TopOil
Temp
Peak
Load
(Per
Unit)
HotSpot
Temp
(0C)
t c)
Peak
Load
(Per
Unit)
1.71
1 . 87
159
185
57
64
1.65
1.80
159
184
64
71
1 . 58
1 . 74
1 58
184
71
78
1.51
1.68
157
184
l.56
1.70
1 .74
152
1 7H
186
67
77
80
1.50
1 . 64
1 . 69
152
1 77
185
73
83
86
1.44
1.59
1 . 63
151
177
185
79
89
92
1 .37
1.52
1 . 57
150
176
184
t C)
1 .1 3
1 . 55
1 . 59
1 . 63
145
1 70
178
186
73
85
89
93
1 .33
1.45
1 .48
1 .5 2
l . 55
1 35
158
165
173
1H2
73
85
88
93
97
1 . 26
1 . 38
1.41
1 .45
1 .48
1.52
1 24
l 46
152
160
1 68
177
68
80
83
87
91
96
1.19
1 .30
1.33
1.37
1.40
1.44
111
1 30
137
141
152
160
61
72
75
79
83
87
1 .37
TopOil
Temp
t e)
Peak
Load
(Per
Unit)
HotSpot
T�mp
( C)
144
1 69
176
185
78
90
94
98
1.31
l.45
1 . 48
l.53
1 44
l . 50
1 . 54
l.58
1 .27
1 . 39
1.43
1 .47
1.51
1 34
1 57
1 65
173
181
77
89
93
97
102
1 . 21
1 . 34
1 . 38
1.42
1.46
73
1 .21
TopOil
Temp
1 . 24
HotSpot
Temp
te)
TopOil
Temp
t C)
Peak
Load
(Per
Unit)
HotSpot
T8mp
TopOil
Temp
78
85
l .4 3
l .6 1
1 56
1 83
R5
92
l . 34
l . 54
154
182
92
99
85
94
98
1 . 29
1 .4 6
1.51
1 49
175
183
90
1 00
103
1 .20
1 . 39
1 ,45
146
174
183
96
1 06
1 09
TopOil
Temp
(0C)
Peak
Load
(Per
Unit)
142
1 67
175
184
-
88
100
103
1 08
1.17
l .33
l .3 7
1.42
141
166
1 74
1 84
-
1.15
l . 28
1.32
1.37
1.11
132
1 56
1 64
1 72
181
-
86
98
102
107
111
-
1 .0a
1 32
156
163
172
83
95
98
103
1.89
1 34
1 57
164
172
1
81
-
82
94
98
102
107
1 68
176
185
HotSpot
Temp
te)
l .4 3
1 .4 8
50
40
30
20
10
1 .23
l . 27
l.31
93
1 05
108
113
-
91
103
107
111
-
( e)
(0C )
1 . 09
l . 26
l .3 1
1 39
165
174
97
109
112
l.00
l.16
l . 20
129
154
162
94
107
111
1 . 36
1 . 39
88
92
96
100
1.15
1 . 27
1.30
1 . 34
1 . 38
1 . 4:3
1 24
145
152
160
167
176
77
89
92
96
100
105
1 . 09
1.21
1 . 25
1 . 29
1 . 34
1 . 38
1 23
1 44
152
1 59
1 68
1 76
82
93
97
101
1 06
110
1 .0 2
1 .1 5
1 .2 0
1 .2 3
1 .2 8
1 .3 2
122
144
152
1 59
167
1 76
86
98
102
1 05
110
114
0.94
1 .09
1 .13
1 .18
121
144
151
159
90
102
1 06
110
l.43
1.47
1 24
145
153
160
168
1 76
1.13
1.25
1 . 28
1.32
1.36
1.39
111
1 31
137
144
152
160
66
77
80
84
88
92
1 . 07
l.19
l.23
1 . 27
1 . 30
l . 34
111
71
81
85
88
92
96
1 . 00
111
131
137
145
152
160
75
86
89
93
97
101
0.93
1 .07
1.11
l.15
l .20
1 .2 6
110
131
137
1 44
152
1 59
80
91
94
98
102
106
0.86
1 .00
1 . 05
1 . 09
1.14
1.18
111
130
137
144
152
Hi9
85
95
99
102
1 06
110
1 . :12
84
1 :W
l :n
145
152
160
1.13
l.17
1 .21
l . 25
1 . 29
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ) , are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
*Actual water temperature should be 5 °e lower than the ambient temperatures shown above (see 3.5), and must be above zero °e.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
t:;J
trl
trl
0
C
.....
t:)
trl
"l
0
�
t""
0
>
t:)
Z
0
�
.....
Z
trl
�
>
t""
6
.....
s:
�
�
trl
�
00
trl
t:)
'"
0
�
trl
�
>-3
::x:J
>
Table 3(k)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Oil-Cooled (Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
E quivalent Load Before Peak Load 90% of Maximum Nameplate Rating
Z
00
"%j
0
::x:J
=
s::
t:rJ
Ambient C c
0
Hours
of
Peak
Loa d
%
2
4
1 . 59
1 . 75
151
177
185
70
80
83
1.41
1.53
1.57
1.61
143
167
175
184
1.32
1 .4 3
1.47
1.51
1.55
1.52
1 . 66
1.71
Normal
0.25
0.50
1 . 00
2.00
4.00
Normal
0.25
0.50
1 . 00
2.00
4.00
0.25
0.50
1.00
2.00
4.00
0. 2 5
0.50
1.00
2 . 00
4 . 00
Normal
24
62
69
158
184
Normal
8
(C)
JPer
ni t )
1 . 66
1 .81
0.25
0.50
1 . 00
2.00
4.00
2
Peak
T�mp
Normal
t-:l
to
Top-
HotSpot
J
Normal
!
Peak
Load
Per
nit)
Loss
of
Life
0.25
0.50
1.00
2 . 00
4.00
Oil
Temp
Hot-
To p-
Oi l
Temp
Peak
HotSpot
(cc)
Load
(Per
Unit)
T�mp
1 57
1 84
70
77
1.51
1 .68
1 56
182
1 . 45
1 .6 1
1.65
149
176
1 84
76
86
89
1 . 38
1 . 54
1 . 59
74
85
89
93
1.34
1 .48
1.52
1.56
142
1 67
175
1 84
79
90
94
98
1 34
156
163
172
181
73
84
88
92
97
1 . 26
1.38
1.42
1 .46
1.50
1 32
156
1 64
172
1 80
1.26
1.37
1.41
1.44
1.48
1.52
1 23
145
152
1 60
167
176
68
79
83
87
91
95
1 . 20
1.32
1.35
1 . 39
1.43
1.47
1.19
1 . 30
1.33
1 . 37
1 .40
1 . 44
111
130
137
144
152
1 60
61
72
75
79
83
87
1.13
1 . 24
1 . 28
1.32
1 . 36
1 . 39
( C)
Load
Spot
Temp
30
20
10
To r
Oi
Peak
Load
HotSpot
40
To r
Oi
T�mp
Load
(Per
Uni t)
HotSpot
Temp
(oC)
Peak
50
TopOil
Peak
Loa d
HotSpot
T� mp
( C)
Oil
Temp
("C)
Top-
(Per
Unit)
Temp
(0C)
Jni t )
76
83
1.41
1.61
1 53
181
83
90
1 . 25
1.53
1 . 59
142
179
189
87
97
100
1 .44
1.52
176
187
104
1 07
148
175
184
81
91
95
1 .30
1 .48
1.53
145
173
182
86
97
100
1.14
1.41
1.46
1 34
172
181
88
103
1 06
1 . 31
1 . 38
167
178
107
111
1.28
1 .4 2
1 .4 6
1 .5 1
140
166
174
1 83
83
95
99
103
1 .2 0
1.36
1.41
1 .4 5
137
165
173
1 82
87
1 00
104
108
1.06
1 . 29
1 . 34
1 . 39
1 27
162
172
180
88
104
109
113
1 . 20
1.27
76
89
93
97
1 01
1 .20
1.33
1 . 37
1.41
1 .45
131
155
163
170
180
81
93
97
101
1 06
1.12
1 .27
1 .31
1.36
1 . 40
1 28
1 54
162
170
179
84
98
1 02
106
110
1.01
1 . 20
1 . 25
1 . :10
1 . 34
121
1 52
160
1 69
178
85
101
1 06
no
115
1.13
1 . 18
1.23
149
158
168
105
109
1 14
123
144
151
159
167
1 76
72
84
87
91
96
100
1.14
1.27
1 . 30
1 . 34
1 . 38
1 .42
122
144
151
1 59
167
176
77
88
92
96
1 01
1 05
1.07
1 . 20
1 . 25
1 . 29
1 . 33
1.37
1 20
14a
151
159
166
175
80
92
97
101
105
109
0.97
1.14
1 . 19
1.23
1 . 27
1 .3 2
115
142
150
158
166
175
83
97
101
1 05
1 09
114
1.07
1.12
1.17
1 .22
141
148
1 57
166
101
105
1 09
114
111
1 30
1 37
144
1 52
1 59
66
76
80
84
88
91
1 . 07
1 .19
1 . 23
1 . 26
1.30
1 . 34
111
130
137
144
152
160
71
81
85
88
92
96
1 . 00
1.13
1.17
1 .2 1
1.25
1 . 29
110
1 30
137
144
152
159
75
86
89
93
97
101
0.93
1 . 07
1.11
1.15
1.20
1 . 24
110
1 30
1 37
144
152
1 59
80
90
94
97
102
1 06
0.85
1 . 00
1 .04
1 .09
1.1 3
1.18
110
130
1 36
1 43
151
1 59
Fl4
95
98
102
1 06
110
(0C)
( C)
Temp
(cC)
(c C)
( C)
Temp
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ) , are given to assist in interpolation of the maximum limit.
% loss of life is in addition to norm al loss of life.
• Actual wRter temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5), and must be above zero C.
°
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
Per
::x:J
00
e
>1;1
>-3
0
.....
0
0
s::
<:
>
�
......
>-3
::t:
c.n
c.n
°
0
0
::x:J
'"
01
158
1 68
1 07
1 12
0°
>
<:
t:rJ
::x:J
>
0
t:rJ
�..
....
Z
t:l
......
Z
0
::x:J
Ul
t:rJ
0
01 >
:-' Z
tC oo
�
....
, �
..... ......
tC t:rJ
oo t:rJ
..... t:rJ
0>
Table 3(1)
Capability Table for Normal and Moderate Sacrifice of Life
65 DC Rise, Forced-Oil-Cooled (Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 100% of Maximum Nameplate Rating
"' Z
:-" 00
"' ....
.., ';::;
��
=
oo trJ
....
Ambient ° c
Hours
of
P ak
Load
e
%
Loss
of
Life
Normal
I
2"
0.25
0.50
1 .00
2 .00
4 .00
Norm al
0.25
0.50
1 . 00
2 . 00
4 . 00
or a
0.25
c.:>
N m l
0
2
0.50
1 . 00
2 . 00
4 . 00
Nurmal
4
0.25
0 . 50
1 .00
2 .00
4 .00
Normal
8
0.25
0_50
1 .00
2 .00
4 . 00
Normal
24
0.25
0.50
1 .00
2 . 00
4 . 00
ek
�
0
20
10
TopOil
Temp
t e)
P a
Load
Per
nit)
HotSpot
T( �mp
C)
1.61
1. 77
157
182
66
73
1 .49
1 .64
1 . 68
149
176
184
71
81
84
HotSpot
Temp
(o
C)
TopOil
Temp
(0 C )
1 .53
1 . 71
1 54
UI2
72
80
1 .4 2
1.58
1 .6 3
148
174
183
-
77
87
90
Peak
Load
Per
nit)
J
30
HotSpot
T� mp
TopOil
Temp
1.43
1 .64
1 50
181
1.32
1.52
1 .56
142
173
181
Peak
Load
(P r
Unit)
e
( C)
Peak
Load
Per
nit)
HotSpot
Temp
78
87
81
93
96
t Cl
81
1 .3 9
1 .5 2
1 . 56
1 .60
142
167
1 75
183
74
86
89
94
1.32
1 .46
1 . 50
1 . 55
139
165
173
182
--
78
90
94
98
1 .23
1.40
1.45
1.49
1 35
1 64
172
181
-
95
99
1 03
1 . 31
1 .4 3
1 . 46
l . 50
1 .54
132
156
163
171
180
72
84
88
92
97
1.25
1 . 38
1.41
1.45
1 . 50
130
154
162
170
180
76
88
92
97
101
1.17
1.32
1 .36
1.40
1 .45
1 . 49
1 26
1 54
161
1 70
179
188
-
1 . 25
1 . 37
1 .4 0
1 .44
1 .48
1 .52
122
1 44
151
1 59
1 67
176
67
79
83
87
91
96
1 . 20
1.31
1 .35
1 .3 9
1 .4 3
1 .4 7
122
143
151
159
167
176
72
83
87
91
96
1 00
1.12
1 . 26
1 . 30
1 . 34
1 . 38
1.42
119
143
1 50
1 58
167
176
1.19
1 . 30
1 . 33
1 .3 7
1 .4 0
1 .44
110
1 30
137
144
152
160
61
72
75
79
83
87
1.13
1 . 24
1 . 28
1 .3 2
1 .35
1 . 39
110
130
137
144
151
159
66
76
80
84
87
91
1 . 07
1.19
1 .22
1.26
1 . 30
1 . 34
llO
1 30
1 37
1 44
151
1 60
40
r
50
t C)
To
Oi
Temp
tC)
Peak
Load
Per
nit)
HotSpot
Temp
(o
e)
TopOil
T� mp
Peak
Load
(Per
Unit)
HotSpot
Tg mp
( e)
TopOil
Temp
(o
e)
1 .00
1 . 56
1 .63
110
179
188
75
94
96
1 .4 5
1.53
173
1 84
99
102
1 .00
1 .39
1 .52
1 30
175
191
95
107
112
1 .00
1 .44
1 .49
1 .5 5
110
170
179
190
75
98
101
105
1 . 34
1.41
1 .4 8
164
176
187
102
106
110
1 .00
1 .28
1 . 39
130
166
183
95
1 09
115
�
�
( C)
110
162
1 70
180
75
99
103
108
1.26
1.31
1 . 37
1 56
168
177
1 02
1 07
112
1 .00
1 . 20
1 . 29
100
1 58
174
95
1 08
1 16
79
93
97
101
106
110
1 . 00
1.25
1 . 30
1 . 34
1 . 39
llO
151
159
168
1 78
75
96
101
105
110
1.17
1 .23
1 . 28
1 .34
147
157
166
177
99
1 04
1 09
1 14
1 .00
1 .1 3
1.21
1 30
151
1 64
95
1 06
112
75
1 . 00
1 . 20
1 . 24
1 . 28
1 . 33
1.37
110
142
149
157
166
174
75
92
96
100
105
109
1.12
1.17
1.22
1.27
1 .3 2
139
148
157
165
1 74
95
100
1 04
109
1 14
1 .00
1 .0 9
1.15
1 . 21
1 30
143
1 54
1 64
95
102
107
113
1 10
1 30
136
144
151
1 59
80
90
94
97
101
105
0.85
1 .00
1 .04
1 .0 9
1.13
1.18
109
1 30
1 36
143
151
1 59
84
95
98
102
1 06
1 10
70
81
84
88
92
96
1 . 00
1.13
1 .16
1.21
1.25
1 . 29
110
130
136
144
152
1 59
75
86
89
93
97
101
trJ
tzJ
Cl
c:::
1 .00
1 .34
1 . 38
1.43
88
92
96
1 00
105
....
tzJ
8
trJ
'""l
0
::0
t"'
0
>
0
Z
Cl
s:::
....
Z
0.93
1.06
1.11
1.15
1.19
1 . 23
NOTE: Underlined values, though beyond recommended limits (see 4.2.2.4), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of Iife_
*Actual water temperature should be 5 °C lower than the ambient temperatures shown above (see 3 . 5 ) , and must be above zero °C_
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
trJ
::0
>
t"'
6
.....
t"'
�s:::
trJ
::0
00
trJ
0
'"I:l
0
::e
tzJ
::0
Table 3(m)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Air-Cooled (OA/F A/F A) Transformers Rated Over 133% of Self-Cooled Rating
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
>oj
::0
>
z
00
"'l
0
::0
=
0
Hours
of
Peak
Load
I
2
1
%
Loss
of
Life
2
Peak
Load
(Per
Unit)
Spot
Temp
o
Hot-
Top-
( C)
Temp
o
Peak
Load
(Per
Oil
( C)
Unit)
Hot-
f
C
y
To -
Oi
Spot
T!im
(
Temp
t Cl
Peak
Load
(Per
Unit)
HotS pot
Te m p
tC)
Toy-
Hot-
Oi
Ts mp
Peak
Load
( Pe
r
Unit)
S pot
Temp
(o
( C)
C)
TopOi l
Temp
( C)
Load
(Per
Ho t Spo t
T5 mp
Peak
Unit)
( C)
Top-
Oil
( C
Temp
o
)
1 .8 8
2.09
1 59
185
63
72
1 .7 9
2.00
1 59
185
70
78
l . 70
1 .9 2
1 59
1 84
77
85
l .60
1 .83
1 58
1 84
83
92
l .50
1.74
1 56
1 83
90
98
Normal
l . 74
1 .9 1
1 .9 7
1 54
179
188
69
80
84
l .66
1 .8 4
l .9 0
153
1 78
186
74
85
89
1 .5 8
1.77
1 .8 3
1 52
178
1 86
80
91
95
1 . 50
1 .69
1.75
152
177
185
85
96
100
l .40
l .6 1
l .67
1 50
176
1 84
90
101
105
1.31
1 .53
1 . 59
1 50
176
1 84
96
107
110
0.25
0.50
l .00
2.00
4.00
0.25
0.50
1 . 00
2.00
4.00
0.25
0.50
1 . 00
2.00
4 . 00
0.25
0 . 50
l . 00
2 . 00
4 .00
Normal
24
Oil
( C)
57
65
Normal
8
C)
To pTemp
o
50
160
1 86
Normal
4
)
Hot-
Spot
T!imp
(
t:rJ
40
l .96
2.17
0_25
0.50
1 .00
2 .00
4 .00
No mal
I-'
(yPer
n it
10
30
Normal
r
C;.:>
Peak
Load
�
Ambient ° c
20
0.25
0 . 50
l . 00
2.00
4 .0 0
::0
00
e:::
'"d
>oj
0
>-'
0
0
�
<:
>
:IE
::3
::c
Q1
Q1
°
0
0
::0
O"l
l . 54
1 . 70
1 .7 4
1 .80
146
1 70
178
187
76
89
93
98
1 .4 7
l .6 3
1 .6 8
1.73
1 .4 0
1 . 54
l . 59
1 . 63
l .68
135
H i8
166
174
182
75
88
92
97
102
1 .33
1 . 48
1 .52
1 . 58
1 .63
1 .32
1 .45
l . 49
l . 54
1 . 59
1 . 63
1 24
145
152
160
168
177
69
82
86
90
95
100
1 . 23
l . 36
1 .40
1 .44
l . 49
1 . 53
111
131
137
144
151
159
62
73
77
81
85
90
145
170
177
186
1 45
1 69
177
1 86
-
142
1 67
176
93
1 06
111
--
1 .1 4
1 . 34
141
1 66
98
111
144
1 68
176
185
89
102
106
111
-
l.23
1 .42
1 .47
1 .19
1 .35
1 .39
1 .4 5
1 .5 0
133
1 56
1 64
172
181
-
87
1 00
104
1 09
1 14
1.11
1 . 28
1 . 33
1 . 38
133
156
163
172
91
1 04
108
113
1 . 03
1 . 20
1.26
132
155
163
78
90
94
98
1 03
1 08
1.11
1 .25
l . 30
1 .3 5
1 .4 0
1 .45
123
1 44
1 52
1 59
1 68
176
82
94
98
102
1 07
112
l .03
1.19
1 . 23
1 . 28
1 . 34
1 23
144
151
159
167
86
98
102
107
111
0.94
l.11
1.16
l . 22
122
144
151
159
90
1 03
107
111
71
82
85
89
94
98
1 .0 1
1.15
1 . 20
1 . 25
1 .30
1 .35
110
1 30
136
144
151
1 59
75
86
90
94
98
103
0.92
1 .08
1.13
1 . 18
1 . 23
1 . 29
110
1 30
137
143
151
1 59
79
90
94
98
102
107
0.84
1 .00
1 . 06
1.1 1
1.16
1 . 21
110
1 30
137
144
151
159
84
95
99
1 03
107
111
85
98
101
1 06
80
93
97
102
1 .4 0
1 .5 6
1.61
1 .67
135
157
165
174
182
-
79
92
96
101
106
1 . 26
1.42
1 .4 6
1.51
1.57
1 34
1 57
1 64
1 73
1
82
-
83
96
1 00
1 05
110
1 . 25
1 . 39
1 .4 3
1 . 48
1 .53
1 . 58
1 23
145
152
160
168
176
74
86
90
95
99
1 04
1.18
1.32
1 .3 7
1 .4 2
1 .4 7
l.52
1 23
145
1 52
160
1 68
177
1 .16
1 . 29
1 . 34
l .38
1 .4 3
1 .4 7
111
130
137
144
1 52
159
66
78
81
85
90
94
1 .0 9
1.23
1.27
1.31
1 .36
1 .4 1
111
130
137
143
151
1 59
1 .32
1 .4 9
1 . 54
1 . 60
CJ1
a
0
>
<:
t:rJ
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 _ 2 . 4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
95
108
ill
::0
>
0
t:rJ
:IE
Z
9
Z
0
::0
..,
00
t:rJ
0
Q1 >
:-' Z
<0 00
", ..,
� -;::.
<o t:rJ
oo t:rJ
..... t:rJ
0>
Ol Z
:-" 00
Table 3(n)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Air-Cooled (OA/FA/FA) Transformers Rated Over 133% of Self-Cooled Rating
Equivalent Load Before Peak Load 70% of Maximum Nameplate Rating
<0 ""'
t-o "j;;:j
' tzj
� tzj
ex>
tzj
.....
=
Ambient ° c
0
Hours
of
Peak
Load
!
2
%
Loss
of
Life
�
1 59
185
61
69
1 .82
2.03
Normal
1 . 70
1 .88
1 . 94
152
178
187
71
82
86
1 .62
1 . 80
1 . 87
0 ,25
0 . 50
1 .00
2 .00
4 .00
0.25
0.50
1 .00
2 . 00
4 .00
N 0orm
a
.25
8
l
0.50
1 .00
2 . 00
1 . 00
Normal
24
Peak
Load
(Per
Unit)
2.1 1
Normal
4
TopOil
Temp
tCl
1 .91
0.25
0.50
1 . 00
2 .0 0
4 . 00
Normal
2
/-Init)
er
HotSpot
T� mp
( C)
Normal
0 . 25
0 , 50
1 . 00
2 ,00
4 , 00
CO
Peak
Load
0 , 25
0.50
1 . 00
2,00
4 , 00
1 . 52
1 . 68
1 .73
1 . 78
1 .40
1 .54
1 . 58
1 . 63
1 . 68
145
1 69
177
1 86
76
89
93
98
1 .45
1 .6 1
1 . 66
1.71
1 34
158
165
173
182
75
88
92
97
102
69
82
86
90
95
1.25
1 .3 9
1.43
1 .4 8
1 ,6:1
124
145
152
160
168
176
1 .2 3
1 . 36
1.40
1.44
1 . 48
1 .53
110
130
137
144
151
1 59
1 .32
1 .4 5
1.49
1 . 54
1 . 58
20
10
1 .3 2
1 .4 7
Hot·
Spot
Temp
(0G )
TopOil
Temp
tC)
Peak
Load
(Per
Unit)
Hot·
Spot
Tsmp
( C)
y
To Oi
Temp
tCl
30
Peak
Load
(Per
Unit)
159
67
76
1 .72
1 . 95
1 57
183
74
82
1 .63
1 .8 6
152
177
186
-
76
87
91
1 .54
1 51
1.73
1.79
81
93
96
1 .45
1 . 65
1.71
.!§.!.
144
169
177
185
1 33
1 57
1 64
177
185
Hot·
Spot
Temp
tC)
y
To Oi
Temp
tC)
40
Peak
Load
Per
it )
Hot·
Spot
Temp
(oC)
�
n
50
Top·
Oil
Temp
(oC)
Peak
Load
(Per
Unit)
HotSpot
Temp
(C )
Top·
Oil
Temp
(0G )
1 56
80
89
1.53
1.77
1 56
182
87
95
1 .3 9
1 .6 7
152
181
93
102
150
175
184
87
98
102
1.35
1.57
1 . 63
148
175
183
92
103
107
1 .23
1 .4 8
1 .54
145
173
182
96
1 08
112
183
-
81
94
98
102
78
92
96
1.37
1 . 54
1 . 59
1 .65
143
1 68
1 76
1 85
-
85
98
102
107
133
82
96
1 00
1 . 29
1 .4 7
1 . 52
1 . 58
142
1 67
175
183
-
105
110
1.18
1 . 34
1 . 39
1 .44
1 .4 9
132
156
1 63
172
180
89
1 02
106
111
86
1 . 20
1 . 39
1.45
140
1 66
1 74
93
106
111
1.10
1.31
1.10
1 31
1 54
90
103
108
113
-
1 . 00
1.19
1 .25
101
105
1 00
74
86
90
94
99
104
1.18
1.32
1 .37
1 .4 2
1 .4 6
1.51
1 23
145
1 52
1 60
1 67
1 76
78
90
94
99
103
1 08
1 . 10
1 . 25
1 . 30
1 . 35
1 .40
1 .4 5
1 22
144
151
1 59
167
1 76
81
94
98
1 02
1 07
112
1.01
1 .18
1.23
1 . 28
1 . 34
121
144
151
1 58
1 67
85
98
102
106
11 1
0,92
1.10
1 .52
1.57
123
145
151
1 60
1 67
176
62
73
77
81
85
90
1.16
1 .29
1 .33
1 . 38
1.42
1 .47
111
131
137
144
151
1 59
66
78
81
85
89
94
1 .0 8
1 . 23
1.27
1 .3 1
1 . 36
1 .4 1
1 10
1 30
137
144
151
1 59
70
82
86
89
94
98
1 .01
1.16
1 .20
1 . 25
1 . 30
1 .35
1 10
1 30
1 37
1 44
151
159
75
0,92
1 . 08
1.13
1 . 18
1.23
1 . 28
1 10
1 30
1 36
143
1 51
1 58
79
90
94
98
102
106
156
1 64
172
ill
1 00
1 04
1 09
ll±
86
90
94
98
102
1 37
164
1
96
10
c:::
""'
t;I
tzj
"%j
0
:;Q
t"
1 73
181
1 .6 2
tzj
tzj
tzj
Q
1.25
1.41
1 .46
1 .50
1 . 56
1 .5 2
1 .57
""'
1 . 26
1.32
1 . 38
162
171
1 28
1 54
1 62
94
108
1
12
-
0
>
t;I
.....
Z
Q
�
Z
tzj
s
NOTE: Underlined values, though beyond recommended limits ( ee 4 . 2 .2.4), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
1.15
1 . 21
119
1 43
1 50
1 58
89
102
106
111
0,83
1 . 00
1 . 06
1 .10
1 .16
1.21
1 10
1 30
1 37
143
1 51
1 59
84
95
99
102
107
111
:;Q
>
t"
6.
....
t"
.:..
�
�
tzj
:;Q
00
tzj
t;I
"C
0
::;:J
tzj
:;Q
..,
Table 3(p)
Capability Table for Normal and Moderate Sacrifice of Life
65 °C Rise, Forced-Air-Cooled (OA/FA/FA) Transformers Rated Over 133% of Self-Cooled Rating
Equivalent Load Before Peak Load 90% of Maximum Nameplate Rating
::0
�
00
"'l
=
Hours
of
Peak
Load
%
�Load
Per
nit)
Spot
Tg mp
Temp
Peak
Load
Per
Normal
l .8 4
2 . 04
158
H l3
66
74
l . 74
1 .96
0.25
0.50
1 .0 0
2.00
4 .00
Normal
1
�
�
0.25
0.50
1 . 00
2.00
4.00
Normal
2
0.25
0.50
l .00
2.00
4.00
No rmal
4
0.25
0.50
1 .00
2 .00
4 .00
Normal
8
0.25
0.50
l . 00
2.00
4.00
N or ma l
24
Top·
Loss
of
Life
0.25
0.50
1 . 00
2 . 00
4.00
Peak
Hot-
( e)
Ambient °c
20
10
0
Oil
(oe)
�
nit)
Hot·
Spot
Temp
(oe)
TopOil
T� mp
( e)
Peak
Load
(Per
Unit)
72
81
1.63
1 .87
157
1 83
-
Hot·
Spot
T�mp
( C)
155
182
y
To Oi
T� mp
trJ
30
( C)
Peak
Load
(Per
Unit)
78
87
1.51
1 .78
Hot·
Spot
Temp
t c)
0
::0
�
y
To Oi
Tg mp
( C)
151
181
-
84
94
40
Peak
Hot·
Spot
Load
�Per
nit
T� mp
( C)
1 . 23
1 . 67
1.75
134
179
188
)
50
Top-
Oil
T� mp
Peak
Load
Hot·
( e)
�Per
nit)
Spo t
Tll mp
86
99
102
1 .54
1 .6 4
175
185
( C)
Top Oil
T16mp
( C)
1 05
1 08
::0
00
e
"d
..,
0
....
0
0
�
<:
>
::e
�
1 .6 5
1 .8 3
1 .8 9
151
176
185
73
84
88
1 . 56
1 . 76
1 . 82
150
176
1
85
-
78
89
93
1.47
1 . 68
1.74
147
175
1
83
-
83
95
98
1 . 35
1 . 59
1 . 66
144
173
182
87
99
1 04
1.10
1 . 49
1 . 57
1 26
171
180
85
1 04
1 08
143
168
176
185
76
89
94
98
1 .42
1 .5 8
1 .6 4
1 .6 9
142
167
175
183
80
93
98
102
1 . 33
1. 51
1 . 57
1 .62
140
166
174
182
84
98
102
107
1.23
1 . 44
1.49
1 . 56
136
1 64
173
182
87
102
1 06
111
1 . 03
1.35
1 .42
122
162
171
85
1 05
110
1 . 38
1 . 53
1.57
1 .6 2
1 .67
133
1 56
164
172
181
74
87
92
96
101
1 .3 1
1 .4 6
1 .51
1 .56
1 .6 1
132
1 56
163
171
180
78
91
95
1 00
105
1.23
1.40
1.44
1 .4 9
1.55
1 .6 0
130
155
162
171
179
189
81
95
99
1 04
109
114
1 . 14
1.32
1 . 37
1.43
1 . 48
1 27
153
162
170
179
84
99
103
1 08
113
0.98
1 . 24
1.30
1.35
1 17
152
160
168
83
102
1 07
111
1 .31
1 . 44
1 .4 9
1.53
1.58
1 .6 3
1 23
144
152
1 59
1 67
176
69
81
85
90
94
99
1 .24
1 .3 8
1 .4 2
1 .47
1 .52
1 . 57
122
144
151
159
167
176
73
85
89
94
98
1 04
1.16
1.32
1 . 36
1.41
1 .4 6
1.51
121
144
151
1 58
1 67
175
77
90
93
98
103
108
1 . 07
1 . 24
1 . 29
1 . 34
1 .4 0
1 .45
119
143
150
1 58
167
175
80
93
98
102
1 07
111
0.95
1 .17
1 . 22
1 . 28
1 . 33
113
142
149
158
166
81
97
101
1 06
110
1 .22
1 .3 6
1 .4 0
1 .44
1.49
1 .53
1 10
130
137
143
151
1 59
62
73
77
81
85
90
1.15
1 .29
1 .3 3
1.38
1 .4 2
1 .4 7
110
130
136
144
1 51
1 59
66
77
81
85
89
94
1 .08
1 .22
1.27
1.31
1 .36
1.41
110
130
1 36
143
151
1 58
70
82
85
89
93
98
1.00
1.15
1 . 20
1 . 25
1 .30
1 .35
110
130
1 37
1 44
1 51
1 59
75
86
90
94
98
102
0.92
1 . 08
1.12
1.18
1 . 23
1 . 29
1 09
130
136
143
151
1 59
79
90
94
98
102
107
(see
4.2.2.4),
are given to assist in interpolation of
166
177
1 08
1 13
°
(1
0
::0
1 .49
1 . 66
1. 71
1.76
NOTE: U nd erlined values, though beyond recommended limits
% l oss of life is in addition to normal loss of life.
::c
1.37
l . 46
C11
C11
the maximum limit.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
1 .24
1 . 32
158
168
1 08
1 13
1 . 14
1 . 22
147
1 58
1 04
1 10
a>
C11
0
(')
>
<:
trJ
::0
>
0
trJ
::e
.....
Z
t;;1
Z
1 . 08
1.14
1 .20
1 40
148
1 57
1 00
1 05
110
l . 00
l . 05
1.11
1.16
1 .22
1 29
136
143
151
159
94
98
1 02
1 06
111
0
::0
.....
00
trJ
("l
01 >
:-' Z
"' 00
t-:> ....
. .... ....
", trJ
ao trJ
.... trJ
n>
Ol Z
;-J oo
Table 3(q)
Capability Table for Normal and Moderate Sacrifice of Life
65 DC Rise , Forced-Air-Cooled (OA/FA/FA) Transformers Rates Over 133% of Self-Cooled Rating
Equivalent Load Before Peak Load 100% of Maximum Nameplate Rating
te .....
t-:> ;::;
�
�
oo trl
,...
=
0
Hours
of
Peak
Lo ad
%
Loss
of
Life
Normal
!
2
156
183
68
77
Normal
1 .6 2
1.81
1.86
150
176
184
74
86
89
0.25
0.50
1 . 00
2.00
4.00
Normal
4
0.25
0.50
1 . 00
2.00
4.00
Normal
8
0.25
0.50
l .0 0
2.00
4.00
Normal
24
(oC)
TopOil
Temp
(C)
1.78
2 .00
Normal
2
�Per
nit)
I
HotSpot
Temp
0. 25
0.50
1 .00
2.00
4.00
0.25
0.50
1 . 00
2.00
4 . 00
!;.j
�
Peak
Load
0.25
0.50
1 .0 0
2 .0 0
4 . 00
1 .48
1 .64
1 .6 9
1 .74
P ea k
Load
(Per
Unit)
l .6 8
l.91
l .52
1 .73
1 . 79
Ambient ° c
20
10
HotSpot
Temp
(oC)
TopOil
T!i mp
( C)
HotSpot
Temp
tC)
40
Tor
Oi
Temp
te)
Peak
1I0t-
(Per
Spot
Temp
(C )
Load
Uni t)
50
TopOil
Temp
Peak
(oC)
(Per
Unit)
Load
HotSpot
T� mp
TopOil
Temp
( C)
(DC)
149
181
80
90
1 . 06
1.71
1 . 80
ll5
178
188
76
96
99
1.56
1.67
172
184
100
1 04
1 . 02
1 .50
l.65
1 31
175
192
95
1 08
114
147
1 74
183
79
91
94
1 .40
l . 64
l. 7 1
142
173
182
82
96
100
1 .03
l.55
l.62
ll2
171
180
76
1 00
1 04
l . 52
l.41
164
177
1
88
-
103
1 09
1
13
-
1 . 02
l . 34
131
1 66
95
110
1 . 30
1 . 38
1.45
156
167
103
109
114
1.01
1 . 23
1 . 34
1 30
158
173
95
1 09
1 16
1 . 38
1 . 52
1 .57
1.61
1 . 66
132
1 56
163
171
1 80
74
87
91
96
101
1 .30
1 .4 6
1 .50
l.55
1 .60
l . 66
130
155
162
171
179
189
77
91
95
1 00
105
110
1 . 30
1 .45
1 . 49
1 .53
1 .58
l .62
122
1 44
1 51
159
167
175
68
81
85
90
94
99
1 .23
1 .3 8
1.42
1 .4 7
1.52
l .57
121
144
150
1 59
1 66
175
62
73
77
81
85
90
l.15
l . 29
1 . 33
l .38
l .4 2
l .47
110
130
137
143
151
159
130
1 37
143
151
1 59
(0C)
30
Peak
Load
(Per
Uni t)
1 . 54
1.82
1 . 39
l . 57
1.62
llO
( C)
y
To Oi
Temp
74
83
76
89
94
98
1 . 23
1 . 36
1 .4 0
1 .44
1 .4 8
l .53
Hot·
Spot
T8 mp
155
182
142
167
175
1 8 4-
l .68
Peak
Load
(Per
Unit)
139
166
174
183
l.28
l .60
1 34
1 64
172
182
82
97
102
107
1 . 02
1.41
1 . 47
1 . 53
1 .43
1 . 49
1 . 54
1 . 59
1 26
1 53
161
170
178
188
79
94
99
1 04
109
l . 02
1 . 30
1 . 36
1 . 42
1 . 47
72
85
89
94
98
103
1 . 14
1.31
1 . 36
1 .40
1 .46
1 .51
118
143
150
1 57
166
175
75
A9
93
97
102
107
1 .01
66
77
81
85
89
94
l . 08
110
130
1 36
143
151
1 59
70
82
85
89
93
98
AO
94
98
103
NOTE: Underlined values, though beyond recommended limits (see
% loss of life is in addition to normal loss of life.
1.49
l . 54
1.61
1 . 20
l .38
l. 22
1 . 27
1 .31
1 . 36
1.41
4 . 2 . 2 . 4 ),
l 14
III
161
171
1 80
111
75
101
1 06
111
151
159
1 69
178
76
98
1 02
1 08
l12
1 . 29
l . 34
1 . 39
1.45
110
142
149
157
166
175
75
92
97
101
106
112
1 . 00
1.15
1.20
1.25
1.30
1.35
110
1 29
1 36
143
151
1 59
75
86
89
94
98
1 02
177
.....
trl
trl
trl
C'l
C
.....
t::I
trl
I'%j
0
:x:J
t""
0
>1.20
1 .27
1 . 34
146
156
167
99
105
III
1 . 00
1.16
1 . 25
1 30
150
163
95
106
l13
t::I
.....
Z
C'l
�
trl
l.23
1.14
1 . 20
1.27
1 .32
138
147
156
164
95
1 00
105
110
l . 08
l.13
1.18
1 . 23
l .28
130
1 36
143
150
159
90
94
98
1 02
1 06
are given to assist in interpolation of the maximum limit.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
1.25
130
143
154
164
95
102
1 08
114
1 .0 5
l.10
l.16
1 .2 1
136
143
1 50
158
98
102
1 06
1 .00
1.10
1.18
::tI
>t;'"
0
.....
t""
�
trl
III
�
trl
t::I
"tI
0
::;:
trl
:x:J
'"'l
:;l:l
Table 3(r)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Oil-Cooled (Non-Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
�
00
"'l
0
:;l:l
�
=
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
1
2
0.25
0.50
1 .00
2.00
4 .0 0
Normal
1
�
0.25
0.50
1 . 00
2 . 00
4.00
Normal
01
2
0 25
0 . 50
1 . 00
2.00
4.00
Normal
4
0 .2 5
0.50
1 .0 0
2 . 00
4 . 00
Normal
8
0.25
0.50
1 .00
2.00
4 .00
Normal
24
0.25
0.50
1 .00
2 .0 0
4 .0 0
Peak
Ho t ·
JPer
nit )
Spot
Ts m p
1 .9 4
2.12
161
187
Load
( C)
Ambient DC
20
10
Top-
Oil
Temp
(0
C)
60
70
Pea k
Load
Per
ni t )
J
1 .85
2 . 05
Hot·
Spot
Temp
o
( C)
160
186
--
TopOil
Temp
(D
C)
66
76
Peak
Load
(Per
Unit)
1 .77
1.97
Hot·
Spot
T� mp
( C)
1 59
185
---
y
To Oi
Tem p
t C)
72
82
30
Peak
Load
(Per
Uni t )
168
189
y
( C)
Peak
Load
(Per
Unit)
Ho tSpot
Temp
(0
78
88
1 . 59
1.81
158
184
Hot·
Spot
Te
(o mp
To Oi
Ts mp
159
C)
185
--
50
40
C)
Top·
Oil
T� mp
( C)
84
94
�
Peak
Load
(Per
Unit)
HotSpot
Temp
To '
Oi
Temp
(0
1 .4 9
1.72
1 56
1 84
90
1 00
(C )
C)
t'l
:;l:l
00
c:::
"'C
'"'l
0
.....
0
0
a:
-<
>
:e
::3
l.71
1.87
1 55
1 80
72
85
1 .63
1.80
1 . 85
1 54
179
188
77
89
94
1.55
1.73
1.79
153
178
1 87
82
94
98
1 . 48
1 . 66
1.72
152
178
186
87
99
103
139
1.59
1 . 64
151
177
185
92
104
108
1.30
1. 5 1
1 . 57
1 50
176
185
96
1 09
113
:I:
01
01
°
n
0
:;l:l
1 .5 1
1 .6 5
1.70
1 .7 5
146
171
178
188
-
79
93
97
102
1.45
l .6 0
1 .64
1 . 69
146
171
178
187
-
83
97
101
106
1 . 38
1.53
1 . 58
1.63
145
169
178
186
-
87
100
105
110
1.31
1 . 47
1.51
1 . 57
144
169
177
186
-
1 . 38
1.51
l.55
l . 59
1 .63
136
158
1 66
174
183
77
91
96
101
106
1 .32
1 .45
1 .49
1 .54
1 . 58
135
158
166
174
182
81
95
99
104
110
1.25
1 . 39
1.43
1 .4 8
1.53
134
157
165
173
84
98
1 03
1 07
113
1.18
1.33
1 . 37
l.42
1 33
1 57
165
173
�
91
1 04
109
1 14
-
1 . 23
1.40
1.45
143
168
176
94
108
113
1.14
1 . 32
88
102
107
112
1.11
1.26
1.31
133
157
164
92
106
110
1 .03
l.19
1 .24
142
166
98
112
'"
01
°
n
>
-<
t'l
:;l:l
132
1 55
163
95
109
113
>
Q
t'l
:e
Z
t::I
1 . 30
1 .4 2
1 . 46
l . 50
1 . 54
1 . 59
1 24
146
152
160
168
177
71
84
88
93
98
104
1 .2 3
1 . 37
1 .4 0
1 .4 5
1 .4 9
1 . 53
1 24
146
152
160
168
177
75
88
92
97
102
1 07
l.17
l .30
1.35
1 .3 9
1.43
1 .4 8
1 24
145
1 53
1 60
168
176
79
91
96
1 00
106
111
1.10
l . 24
1 . 29
1.33
1 . 38
123
145
152
1 60
1 68
82
96
100
1 05
110
1.02
1.17
1.22
1.27
1.32
122
145
1 52
1 59
167
86
99
104
1 08
113
0.94
1 .1 0
1.15
1 . 20
122
144
152
1 59
90
1 03
107
112
1.21
1 .33
1 . 37
1 .4 1
1 . 45
1 . 50
111
130
1 37
144
151
159
63
75
79
83
88
93
1.15
1.27
1.31
1 .35
1 .4 0
1 .4 4
111
130
137
144
151
159
67
79
83
87
91
96
1 .0 8
1.21
1.25
1.30
1 . 34
1 .39
110
130
1 37
144
151
1 59
71
82
87
91
95
100
1 .01
1.15
1.19
1 .23
1 .2 8
1 . 33
111
130
1 37
144
151
160
75
87
91
95
99
1 04
0.93
1.08
1.12
1.17
1.21
1 . 26
110
130
1 37
143
151
1 59
79
91
95
99
103
108
0.84
1.01
1 . 05
1.10
1.15
1.20
110
1 30
1 37
1 44
1 51
1 59
83
95
99
103
1 07
112
NOTE: Underlined valup.s, though beyond recommended limits (see 4 . 2 . 2 . 4 ), are given to assist in interpolation of the maximum limit.
% loss o f life is i n addition to normal loss o f life.
*Actual wllter temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5), and must be above zero °c.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
Z
Q
:;l:l
H
00
trl
�>
:-" '2:
",
00
� H
;. �
", trl
oo trl
..... trl
n ;.-
tll z
:-' tIJ
� ", ,;::;
Table 3(8)
Capability Table for Normal and M oderate Sacrifice of Life
65 ° C Rise, Forced-Oil-Cooled (Non-Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 70% Maximum Nameplate Rating
�
gJ
oo l'J
=
.....
Ambient ° c
0
Hours
of
Peak
Load
%
1 .80
2.00
1 59
185
1 .6 7
1 .8 3
1 . 89
1 54
179
187
74
86
91
1 . 59
1 .77
1.82
1 52
178
186
1 .4 9
1 . 64
1 .68
1.73
145
170
178
187
79
93
97
103
1 .43
1 . 57
1 .6 2
1 .6 7
Normal
0.25
0 . 50
1 . 00
2 .00
4 .00
0.25
0.50
1 .00
2.00
4 .0 0
Normal
0.25
0.50
1 .00
2.00
4 . 00
Normal
24
64
73
1 .8 8
2 . 07
Normal
8
1 59
185
Normal
Normal
4
/;nit)
HotSpot
Temp
(0C)
/;nit)
0.25
0.50
1 . 00
2.00
4 . 00
2
Peak
Load
Per
HotSpot
T!;mp
( C)
0.25
0.50
1 . 00
2.00
4 .00
0.;,
0)
TopOil
Temp
( oC)
Peak
Load
Per
Loss
of
Life
0.25
0.50
1 . 00
2.00
4 . 00
10
145
169
177
186
30
20
Peak
Load
(Per
Unit)
HotSpot
T!;mp
( C)
70
80
1.7 1
1.92
1 58
1 84
79
91
95
1 .52
1 . 70
1 .7 5
TopOil
Temp
(oC)
83
96
101
106
1.36
1.51
1 . 56
1 .61
TopOil
T!lmp
( C)
Peak
Load
(Per
Hot-
y
To Oi
Temp
tC)
40
Peak
Load
(Per
Hot-
50
TopOil
Temp
tc)
Peak
Load
(Per
Hot-
TopOil
Unit)
Spot
Temp
tc)
76
86
1 .6 2
1 .8 3
157
184
82
91
1.52
1.75
1 56
183
88
98
1.39
1.66
1 53
182
93
1 04
152
177
186
84
96
1 00
1 .4 3
1 .6 2
1 .68
1 50
177
185
88
101
105
1.34
1 . 54
1.61
148
175
1 84
93
105
110
1.23
1 .4 6
145
174
97
1 10
144
168
177
185
87
100
105
110
140
166
175
94
1 08
113
1 .10
1.30
1 37
165
97
112
1 .2 8
1 . 44
1.49
1.55
142
167
176
184
90
1 04
109
1 14
Unit)
1.19
1.37
1.43
Spot
Temp
(0C)
Unit)
Spot
Temp
t C)
Temp
(oC)
-
l'J
l'J
l'J
0
c:
8
l'J
"l:J
0
::0
t'"
1 .37
1 . 50
1 . 54
1 . 59
1.63
1 34
1 58
165
1 74
1 82
76
91
95
101
1 06
1 .3 1
1 .44
1.48
1 .53
1.58
1 34
157
164
173
182
80
94
99
1 04
109
1 . 24
1.38
1 .42
1 .47
1.52
1 33
1 56
164
173
181
8 ·1
9H
102
108
113
1.17
1.32
1 . 36
1 .4 1
132
1 56
163
172
87
101
106
111
1.09
1.25
1 . 30
1.35
131
155
162
171
91
105
109
115
1 . 00
1 .1 8
1 . 23
1 28
1 54
161
93
108
113
1 . 29
1 .4 2
1 .4 6
1 .5 0
1 .5 4
1 .5 9
1 23
145
1 52
1 60
1 68
177
71
84
88
93
98
104
1.23
1.36
1 .4 0
1 . 44
1.49
1 .53
123
145
152
1 59
168
176
74
88
92
97
102
107
1.16
1 . 30
1 . 34
1.39
1 . 43
1 . 48
1 23
145
151
159
168
176
78
91
95
1 00
105
llO
1.10
1 . 24
1 . 28
1 . 33
1 . 37
1 . 42
1 23
144
1 51
1 59
1 67
175
82
95
99
1 04
109
114
1.01
1.17
1.22
1 . 26
1.31
121
144
151
158
167
86
99
103
107
113
0.92
1.10
1.15
1.20
1 20
143
1 50
1 58
89
102
1 07
111
1 .2 1
1 . 33
1 .3 7
1.41
1 .4 5
1 .49
110
130
137
144
152
1 59
63
75
79
83
88
1.14
1 . 27
1 .3 1
1 .3 5
1 .4 0
1 . 44
110
130
1 37
1 44
151
1 59
67
79
83
87
92
96
1 . 08
1.21
1 . 25
1.29
1 .34
1 . 38
110
130
137
144
151
159
71
83
87
91
96
100
1.01
1.14
1.19
1 . 23
1 . 28
1 . 33
110
130
136
1 44
151
159
75
87
90
95
99
1 04
0.92
1 . 08
1.12
1 .17
1 . 21
1 . 26
110
1 30
1 36
143
151
158
79
91
94
99
103
108
0.84
1 . 00
1.05
1.10
1.15
1.20
110
130
136
143
151
1 59
83
95
99
1 03
107
112
93
0
;.t:l
Z
0
s=
-
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
*Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5), and must be above zero °c.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
Z
l'J
::0
;.t'"
0
t::
,:...
s=
s=
l'J
::0
tIJ
l'J
t:l
..",
0
::6
tr:I
::0
Table 3(t)
Capability Table for N onnal and Moderate Sacrifice of Life
65 ° c Rise, Forced-Oil-Cooled (Non-Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 90% of Maximum Nameplate Rating
'"'l
::0
:>
Z
00
"%j
0
::0
=
Ambient
10
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
1
2
0. 2 5
0.50
1 . 00
2 . 00
4 . 00
Norm al
0.25
0.50
1 . 00
2 . 00
4.00
1
CJ:>
...::J
Normal
2
0.25
0.50
1 . 00
2.00
4.00
N orm al
4
0 . 25
0.50
1 .0 0
2 . 00
4 .00
Normal
8
24
Peak
�Per
nit)
Load
Top·
Oil
Temp
Peak
Load
�Per
Hot·
Spot
Temp
Top·
O il
T�mp
Peak
Load
Hot·
Spot
T�mp
s::
°e
30
r
To
Oi
Temp
Peak
Load
(Per
Unit)
Hot·
Spot
Temp
40
r
Peak
To ·
Oi
Temp
Load
50
Hot·
S pot
Temp
Top·
Oil
Te mp
te)
(Per
Un i t )
1.80
2.01
1 58
185
68
78
1.71
1.92
157
1 84
74
84
1.61
1 .8 4
155
183
80
90
1 . 49
1 .7 5
151
182
85
96
1 . 26
1 .65
138
180
87
1 02
1 . 62
1.79
1 .8 5
151
1 78
186
76
89
93
1 . 54
1.72
1.77
150
177
185
81
93
97
1 .4 5
1 . 64
1.70
1 48
175
184
85
98
102
1 . 34
Ui 6
1 .6 3
145
1 74
183
8H
1 02
107
1.13
1 .4 8
1 . 54
130
172
181
87
106
( C)
te )
nit)
te)
( e)
(Per
Unit)
( e)
te)
te)
tC)
( C)
Pe a k
Load
(Per
Ho t ·
Spot
Temp
Top·
Oil
Temp
1 .5 2
1.62
1 75
186
106
110
Unit)
tC )
(oC)
t'l
::0
00
e::
"tI
'"'l
0
......
0
0
s::
<:
:>
::!l
::3
III
::r:
1 .36
167
110
en
en
°
C':l
0
::0
1.47
1 .62
1 . 66
1 .71
143
1 69
176
185
79
93
97
1 03
1.39
1.55
1 . 60
1 .6 5
142
167
1 75
184
82
97
101
1 06
1 .32
1.48
1.53
1 .59
140
166
174
184
86
1 00
105
110
1.22
1 .4 1
1.46
1.52
136
165
173
182
88
1 01
1 09
114
1.05
1.33
1 . 39
1 24
1 62
171
86
1 07
ll2
en
CJl
1 . 23
1 . 30
1 57
168
1 09
115
°
("J
:>
<:
t<:!
1.36
1 . 49
1.53
1 . 58
1 . 62
0.25
0.50
1 . 00
2 . 00
4 . 00
1 . 29
1 .42
1 .45
1 . 49
1.54
1.58
Normal
1 .21
0 . 25
0.50
1 .00
2 . 00
4 . 00
Hot·
Spot
T�mp
20
1.33
1.37
1.41
1 . 45
1 . 49
133
156
1 64
172
76
90
95
1 00
105
1 . 29
1.43
1.48
1.52
1.57
123
145
152
159
168
176
70
84
88
93
98
103
110
130
137
144
151
159
63
75
79
83
88
93
ill
::0
>
132
156
1 64
172
79
94
98
1 03
1 09
1.22
1 . 37
1 .42
1 .4 6
1 .5 1
131
155
1 63
171
180
82
97
1 02
1 07
112
1.13
1.30
1.35
1 .4 0
1 27
154
162
170
85
1 00
1 05
110
1 . 00
1 . 23
1.28
1 . 33
119
152
1 60
1 69
84
103
1 08
l l3
1.14
1.20
149
1 58
105
1.22
1.36
1.40
1.44
1.48
1.53
122
1 44
151
1 59
1 67
175
74
87
92
96
101
106
1.15
1 . 30
1 . 34
1 .3R
77
91
95
1 00
105
110
1 . 07
1 . 23
1 . 28
1.32
1.37
1 .4 2
119
143
151
158
1 66
1 75
80
94
99
1 04
1 08
114
0.96
1 . 16
1 . 20
1 . 26
1 .31
114
142
149
158
166
81
98
102
107
112
1 . 07
1 .13
1 . 19
1 39
148
157
100
1 05
110
1 . 43
1 . 4R
121
144
151
159
167
176
1.15
1 . 27
1.31
1.35
1 . 39
1.44
110
1 30
137
1 44
151
159
67
79
83
87
91
96
1 . 08
1 .21
1 . 25
1 . 29
1 . 34
1 . 38
110
1 30
1 37
1 44
151
1 59
71
83
87
91
95
100
1 . 00
1 . 14
1.18
1.23
1.28
1 . 33
110
1 29
1 36
144
151
159
75
86
90
95
99
1 04
0.92
1 . 07
1.12
1.17
1.21
1 .26
1 10
1 29
136
143
1 51
1 59
79
90
94
99
1 03
1 08
1 . 00
1 . 05
1 .10
1.15
1 . 20
1 29
1 36
143
151
159
94
98
102
107
112
ill
NOTE: Underlined values, though beyond recommended limits (see 4 . 2 . 2 . 4 ) , are given to assist in interpolation of the maximum limit.
% loss of li fe is in addition to normal loss of life.
0
*Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5) , and must be above zero e .
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
III
0
t<:!
::!l
""'
Z
0
""'
Z
0
::0
......
00
t<:!
("J
01 >
:" Z
10 00
1<> ""'
, ...... ""'
IO tJi
co t<:!
>-' t<:!
('J >
"' Z
Table 3(u)
Capability Table for Normal and Moderate Sacrifice of Life
65 ° C Rise, Forced-Oil-Cooled (Non-Directed Flow - FOA, FOW * , and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 100% of Maximum Nameplate Rating
:--' 00
<Ll ""'
"" -;:;
�
�
oo tz:!
=
.....
Ambient °c
0
Hours
of
Pea k
Load
%
Peak
of
Per
Loss
2
00
2
4
8
24
1.75
1 . 96
Load
Hot-
( C)
Unit )
1 57
183
71
81
1 .6 5
1 .88
1 54
183
1.59
1 .7 6
1 .81
150
176
184
77
90
94
1.19
1.69
1.75
Normal
0.25
0.50
1 . 00
2 . 00
4 . 00
1 .4 5
1.60
1 . 65
1.70
141
1 67
175
184
78
93
98
103
Normal
0 . 25
0.50
1 . 00
2 . 00
4 .00
1.35
1 .4 8
1 .53
1.57
1 . 62
132
155
163
171
181
Normal
0.25
0.50
1 . 00
2.00
4.00
l . 29
l .4 1
l .45
1 . 49
1.54
1 . 58
Normal
1.21
Life
0.25
0.50
1 . 00
2.00
4.00
0.25
0.50
1 . 00
2 . 00
4.00
C>:l
Spot
Temp
Peak
Spot
Temp
(o
Normal
1
�Load
nit)
To pOil
Temp
o
(Per
Normal
!
Hot-
10
0.25
0.50
1 . 00
2.00
4 . 00
30
20
T opOil
Hot-
TopOil
Temp
( C)
Unit)
1 . 06
1 . 69
l.76
115
179
188
76
98
102
1 .66
1. 55
173
185
84
99
1 03
1 .03
1.52
1 .59
1 13
170
180
76
102
107
1 . 39
1 .4 9
164
177
134
164
172
182
83
100
105
110
1 .02
1 . 38
1 .4 4
1 .5 0
111
162
170
HlO
75
l oa
1 08
113
l .19
l . 36
1.41
1.45
1.51
1 26
1 53
162
170
179
80
96
1 01
106
1 12
-
1 .0 1
1 .29
l . 34
1 . 39
111
152
160
169
75
99
1 04
110
fl 7
91
96
101
1 06
1 .1 3
1 . 29
1 . 33
1.38
1 .43
1 .47
118
143
1 50
158
167
175
76
90
95
1 00
105
110
l . 00
l . 22
1.27
1.32
1.36
1.41
110
141
149
1 57
1 65
175
75
93
98
103
1 08
1 14
67
79
83
87
91
96
1 .07
1 .21
1 . 25
1 . 29
1 . 34
1.38
110
130
136
143
151
159
71
82
86
91
95
1 00
1 . 00
1.14
1.18
1.23
1 . 28
1.32
11 0
1 29
136
143
151
1 58
75
86
90
95
99
1 04
Load
Spot
( Per
T� mp
77
87
1.52
1 .79
1 49
181
81
93
147
175
184
81
94
99
1 . 38
1 .6 1
1 .67
142
173
182
1.37
1.54
1.58
1.63
1 39
1 66
174
183
-
82
97
101
1 06
1 . 27
1 . 46
1.51
1.57
75
89
94
99
105
1 .2 8
1.42
l .1 7
1.51
1.56
130
155
162
171
180
78
93
98
1 03
1 08
1 22
144
151
1 59
1 67
176
70
83
88
92
98
103
l .22
l.35
1 . 39
1.43
1.48
1 .53
121
143
151
1 58
1 67
175
110
1 :30
1 36
1 44
1 52
1 59
63
75
79
83
88
92
1.14
1 . 27
1.31
1 . 35
1.39
1 .44
1 10
130
1 37
144
151
1 59
(C )
C)
40
Hot-
TopOil
Temp
Peak
T( �mp
C)
Unit)
( C)
Temp
tCl
Peak
Load
(P er
Uni t )
Hot-
Spot
(C )
Peak
Load
(Per
50
TopOi l
Spot
Temp
(o
Temp
C)
Peak
Load
Hot-
Spot
TopOil
r
Tem
(
(Per
Temp
(
102
107
1 . 02
l.47
1 . 62
1 :1 1
1 74
191
95
109
115
1 05
111
1.02
1 . 33
131
1 66
95
111
( C)
Unit)
0
e
)
oe
;;
tz:!
tz:!
Q
c::
......
1 . 28
1 . 35
157
1 67
104
110
1.01
1 .22
1 30
1 58
95
110
I:;j
tzJ
"%j
0
�
t"'
1 . :3:3
1 . 37
1.41
1 .45
1 . 49
7:3
0
1.20
1 . 26
1.32
1 47
1 57
167
1 01
1 06
112
l . 00
1.15
1 . 23
130
1 50
163
95
106
114
>
I:;j
H
Z
Q
S::
......
Z
1 . 1 :1
1 .2 0
1 . 2.';
1 . 30
1 :3R
1 48
1 56
165
96
101
106
112
1 . 00
1 .09
1.17
1 .2 3
130
143
154
164
95
102
1 09
115
tz:!
�
>
t"'
6
t=:
H
1 .0 7
1.12
1 . 16
1 .21
1 . 26
1 29
1 36
143
1 50
158
90
94
98
103
108
NOTE: U nderli n ed values, though beyond recommended limits (see 4 . 2 . 2 . 4 ), are given to assis t in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
* Actual w�ter temperature should be 5 ° c lo we than the ambient temperatures shown above (see 3.5), and must be above zero DC.
r
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
1.05
1 . 09
1.15
1 . 20
136
143
151
1 58
98
1 02
107
112
S::
S::
tz:!
�
00
tz:!
I:;j
'"C
0
:;;
tzJ
�
TRANSFORMERS UP TO 1 00 M V A WITH 55 ° C OR 65 °c AVERAGE WINDING RISE
in oil rise, time is required for a transformer to
reach a stable temperature following any
change in load. Therefore, higher peak loads
may be carried for short durations . This is
reflected in the Loading Tables and the basic
equations in 6.7.3.
If the transformer characteristics are not
accurately known, a maximum top-oil te mper­
ature derived from Fig 4 may be used as an
approximate guide. Loading from Fig 4 is
based on a difference of 20 ° C between the
hottest-spot temperature and top-oil te mper­
ature at rated load for self-cooled transformers,
25 ° c for forced-air-cooled transformers ( 133%
and under), and 28 ° C for forced-oil-cooled
transformers.
5 . 1 . 2 . 2 Continuous Loading on Basis of
Average Winding Test Temperature R ise . For
each ° c in excess of 5° that the average
winding test temperature rise is below 55 ° C
the transformer load may be increased above
rated load by the percentage given in Table 1 .
A 5 ° margin is taken to provide a tolerance in
the measurement of temperature rise. The load­
ability thus obtained is that which the trans­
former can carry at 55 ° C rise. Since this may
increase the loading beyond that contemplated
by the designer, the limitations given in 3 .1
should be checked before taking full advantage
of this increased loadability.
Some transformers are designed to have the
differences between the hottest-spot and aver­
age conductor temperatures greater than the
10 ° C allowance. This will result in an average­
winding temperature rise of less than 55 °C,
but the hottest-spot winding temperature rise
may be at the limiting value of 65 D C. Such
transformers should not be loaded above their
rating as outlined in this section. The manu­
facturer should be consulted for information
on the hottest-spot allowances used for these
designs. This condition may exist in trans­
formers with large differences (greater than
20 ° C) between top- and bottom-oil temper­
atures and may be checked approximately by
measuring the top and bottom radiator temper­
atures . Whenever possible, data on hottest-spot
and oil temperatures obtained from factory
temperature tests sh ould be used in calculating
transformer loadability or when calculating
temperatures for loads above rating.
5.1 . 2.3 Loading on Basis of Short-Time
Loads above Rating. Transformers may be
operated above 95 ° C hottest-spot temperature
5 . Transformers Specified to have an Average
Winding Rise of Not More Than
55 °C and Hottest-Spot Winding
Rise of Not More Than 65 ° c
5.1 Basi c Loading for Normal Life Expectancy
5 .1.1 Basic Conditions
(1) The basic loading of a transformer for
normal life expectancy is continuous loading at
rated output when operated under normal
service conditions as indicated in 2.1.1 ( 1 ) ,
2.1 . 1
(2),
2.1.1
(3)
o f ANSI/IEEE
C5 7.1 2.00-1979 [ 3] . It is assumed that opera­
tion under these conditions is equivalent to
operation in a continuous ambient temperature
of 30 ° C for cooling air or 25 ° C for cooling
water. Normal life expectancy will result from
operating with a continuous hottest-spot tem­
perature of 95 ° C (or equivalent variable tem­
perature with 105 ° C maximum) in any 24 h
period.
(2) The hottest-spot winding temperature
determines loss of life due to loading. This
temperature cannot be directly measured on
commercial designs because of the voltage
hazard when placing a temperature detector at
the proper location. The hottest-spot allow­
ances are based on tests of laboratory models.
(3) The hottest-spot temperature at rated
load is usually taken as the sum of the average
winding temperature and a 1 0 ° C allowances
for the hottest spot. For mineral-oil-immersed
transformers operating continuously under the
foregoing conditions with normal life expect­
ancy, this temperature has been assumed to be
a m aximum of 95 ° C .
5 . 1 . 2 Loading for Normal Life Expectancy
under Spec ified C onditi ons
5 . 1 . 2. 1 Loading by Oil Temperature. Oil
temperature alone should not be used as a
guide for loading transformers. The hottest­
spot to top-oil gradient at full load should be
determined from factory tests using Eq 8 or,
lacking data, a value should be assumed. The
full-load h ottest-spot to top -oil gradient should
be corrected to that for the actual load carried
using Eq 7 or Fig 9. This gradient subtracted
from 95 ° C will give the maximum permissible
oil temperature for normal life expectancy. It
should be recognized that, due to thermal lag
5 If cooler
inlet and outlet temperatures are available,
better e stimate of the h o t test ·spot temperature is
poss i ble by making an adjustment in the 1 0 0 C allow·
ance. Consult with the manufacturer.
a
ANSI/IEEE
C57.92·1981
39
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92·1981
2.0
IEEE GUIDE FOR LOADING MINERAL·OIL·IMMERSED POWER
�""
�
�
� �'\.
�
�
� � '\\
I�0� .
A SELF COOLED
B
C
1.6
'"
a
0
..J
>Z
::>
c::
LU
<l.
1.6
1 .4
1 2
1 .0
FORCED AIR
FORCE D OIL
"'-
r---..,
I
r"\.
b...
'"
o
10
20
30
50
40
TOp · O IL TEMP ·C
�1\
60
70
80
90
F ig 4
Approximate Continuous Loading for Nonnal Life Expectancy°
5 5 C Rise Transformers
for short periods provided they are operated
for much longer periods at temperatures below
95 ° C. This is due to the fact that thermal
aging is a cumulative process and thus permits
loads above the rating to be safely carried
under many conditions without encroaching
upon the normal life expectancy of the trans·
former. Suggested loadings for normal life
expectancy are given in Tables 5(a)-5(u). For
conservative use of these tables, it is suggested
that the 5 ° C margin described in 3 . 5 . 1 be used
in determining the ambient temperature.
5.1 .2.4 Loading by Hottest-spot Temper­
ature Indicator. Hottest-spot temperature de·
vices are supplied, when specified, which indi­
cate a simulated hottest-spot temperature.
These devices may be used as a guide to limit
loads.
Thermal relays, when supplied, indicate tem­
peratures reached in the windings. These relays
are calibrated for use with specific transformers
and simulate the hottest-spot temperature by
taking into account preceding loading, existing
load and ambient temperature. Higher loads are
permitted for short periods than for long
periods of time because of the transformer's
time-constant.
5.1 .2.5 Basis for Normal Loss of Life
Loading in Tables 5(a)-5(u). The transformer
capabilities for normal loss of life in Tables
5(a)-5(u) are based on operation at temper­
atures that result in aging equivalent to that for
continuous operation at 9 5°C hottest-spot
temperature as determined from Fig 1 and the
hottest-spot temperature profile resulting from
the converted load cycle and ambient condi­
tions during a 24 h period . The 95 ° C hottest­
spot temperature is based on the hottest-spot
rise of 6 5 ° C plus the standard ambient temper­
ature of 30 DC. At 95 ° C insulation temper­
ature, Fig 1 indicates the life would be 6.5
1 04 hours or over seven years. Actually a
transformer operating outdoors at rated ca­
pacity would have a much longer life because
the annual average ambient air temperature in
most locations in the US does not exceed
°
20 C by more than a few degrees. At 85 ° c
°
(20 C ambient temperature plus 6 5 ° C hot­
test-spot rise), Fig 1 indicates the life would be
2
105 hours or over 22 years. If the loading
over weekends is lighter, as is normally the
case, the total life could extend to over 30
years.
In areas where the annual mean ambient
•
.
40
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
TRANSFORMERS UP TO 100 MVA WITH 55 °C OR 65 ° c AVERAGE WINDING RISE
ANSI/IEEE
C57.92·1981
2.0 �----+-----+---4---��---r�---+�--�
0.5 1------+-----+---____+-----�--_+
0. 3 1------+---+--I---j,I"'--,4
0.2 1------+---..Jt---+--1
0.1 �----+-�--+-�--�--��____���--_+----�
0 .05 L-__-L�__�J_�__�__-L_L__L__L____�____�
130
1 20
110
100
90
HOTTEST�SPOT TEMPERATURE IN ·C
140
150
*Expressed as percent loss of life for one occurrence of
specified ti me duration for operation at temperature
indicated.
Hottest-Spot Temperature in Degrees
Maximum Loss of Life (%)
Duration
Hours
!
2
1
2
4
8
24
0.1
0.25
0.50
1.00
2.00
4.00
141
134
127
120
113
104
151
143
1 36
1 29
1 22
112
151
143
136
129
118
151
143
1 36
1 25
151
143
1 32
ill
139
Fig 5
Maximum Percent Loss of Life - 55 °c Rise Transformers
temperature exceeds 25 ° C the capability
values in the tables should be reduced 1 . 5% for
every degree the mean annual temperature
exceeds 20 ° C . (See 3.1 .2 .5 for explanation).
The method used to calculate Tables 5(a)5(u) is given in Section 7.
5.2 Short-Time Loading with Moderate Sacri­
or the cumulative aging effect of a number of
load cycles is greater than the aging effect of
continuous operation at rated load over the
same period of time, the insulation deteriorates
at a faster rate than normal. The rate of
deterioration is a function of time and temper­
ature and is commonly expressed as a percent­
age loss of life. Charts and tables showing
percent loss of life for various combinations of
time and continuous temperature are given in
Fig 5.
fice of Life Expectancy
5.2.1 Aging of Insulation Due to Operation
above 95 ° C Hottest-Spot Temperature
( 1 ) When the aging effect of one load cycle
41
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92-19S1
IEEE GUIDE FOR LOADING MINERAL-OIL·IMMERSED POWER
( 2) It should be clearly understood that,
restricted air circulation caused by buildings,
while the insulation aging information used is
fire
considered to be conservative and helpful in
history
estimating the relative loss of life due to loads
operator; and variations in design character­
above
rating
an
etc ;
which
previous
may
emergency
loading
be
to
not
known
the
4. As a guide, an
1% per year or 4% in any
istics from those in Table
under various conditions, this
information can only be
walls,
average loss of life of
indicator of trans­
former insulation life. Deterioration of insula­
one emergency operation is considered reason­
tion is generally characterized by a reduction in
able by some users.
both
5 . 2. 2 Methods for Determining Loads above
mechanical and dielectric strength, but
these characteristics m ay
not necessarily
Rating with Some Sacrifice of Life Expectancy
be
directly related. In some cases, insulation in a
5.2 . 2. 1 Transformers with Known Specific
charred condition will have sufficient strength
Characteristics. If the specific characteristics of
to withstand normal operating electrical and
a transformer are known and maximum recom­
mechanical stresses. A transformer having insu­
mended capability is required , the user may
lation in this condition may continue in service
calculate the oil-rise and hottest-spot temper­
for many months or even years if undisturbed.
ature using either the graphic solution illus­
On the other hand, any unusual m ovement of
trated in Section 6, or the basic formulas in
the conductors,
caused by
6 . 7 . With this data, the user may determine the
of the conductors due to heating
allowable load for his conditions by taking into
expansion
such as may
be
resulting from a h eavy load or to large electro­
account
magnetic forces resulting from short circuit,
number of such loads during the life of the
may disturb the weakened insulation such that
transformer, and the approximate percentage
tum-to-tum or layer-to-layer failure will result.
of life he is willing to sacrifice.
( 3 ) The
uncertainty
of
service
the
ambient
temperature,
probable
5.2.2.2 Transformers with Unknown Spec­
conditions
and wide range in ratings covered are reasons
ific
why this loading guide is made conservative in
When
its suggested loadings.
not
Some of the variables
Characteristics
or
Conservative
Loads.
spec ific transformer characteristics are
known
or when
conservative
operation
are : wide differences in ambient temperature
above rating is satisfactory, refer to the Capa­
between
bility Tables , Tables 5(a)-5( u), for tabulations
localities ;
differences
in
elevation ;
Table
4
5 5°C Rise Transformers - Assumed Characteristics at Rated Load
OA
or
OW
Hottest-spot conductor
temperature rise (above
ambient) °c
Top·oil temperature rise
(above amb ie nt) ° c
Top-oil time constant, (h)
Hottest-spot conductor time
constant, ( h )
of load to iron losses
*m (winding exponent)
*n (oil exponent)
Ratio
FA
1 3 3%
or Less
FA**
over
133%
Non·Directed
FOA or FOW
Directe d
FOA or FOW
65
65
65
65
65
45
3.0
40
37
1.25
37
1.25
37
1 .25
0.08
5.0
O.OS
5.0
0.8
1.0
0.08
5.0
1 .0
1 .0
O.OS
3.0
0.8
0.8
2.0
0.08
3.5
0.8
0.9
O.S
0.9
*m is the exponential power of winding loss versus winding temperature rise.
*n is the exponential power of total loss versus top-oil temperature rise.
The indicated values of m and n are approximate, particularly in the more complicated designs, and are subject to
further study .
* *Some OA/F A/F A designs follow more closely the values for FA (133% or less).
42
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92-1981
TRANSFORMERS UP TO 1 00 MVA WITH 55 ° C OR 6 5 ° c AVERAGE WINDING RISE
data shown in Fig 1, the assumed transformer
characteristics from Table 4 and the calculated
hottest-spot temperature profile for the daily
load cycle and ambient temperature condition
that exists during a 24 h period_ The loss of life
values shown in Tables 5(a)-5(u) are in addi­
tion to the normal loss of life of 0.0369% per
24 h which would result from continuous
operation at rated load in a constant 30 °C
ambient.
of permitted loads of various durations follow­
ing explicit preload conditions.
5 _2.2.3 Assumed Characteristics for Trans­
formers which Allow the Loadings in Tables
5(a)-5(u). Transformers vary widely in the
characteristics which affect their short-time
capabilities. Any general guide which applies to
all transformers of a given class must be based
on characteristics which give conservative re­
sults. The characteristics shown in Table 4 are
considered typical of a p ower transformer and
are for general use.
Index for Table 5
55 ° c Rise Transformers
5.2.2.4 Temperature and Load Limitations.
The following are recommended individually
limiting temperatures and loads and are used in
Tables 5(a)-5(u).
(1) Maximum top-oil
1 00 ° C
temperature ( 2 ) Maximum hottest-spot
1 50 °C
conductor temperature (3) Maximum short-time
loading 2 . rating
5.2.2.5 Load Cycles. Transformers usually
operate on a load cycle which repeats each
24 h. This load cycle may be constant or it
may have one or more peaks during the 24 h
period. The actual load cycle may be converted
to a two-step cycle by the method given in 6 .6 .
Where actual average loads before the peak
load differ from those in the tabulations,
sufficient accuracy can be obtained by inter­
polation.
( A Tabulation of Loads for Normal and
Moderate Loss of Life)
Type of Cooling
(a)
(a)
(b)
(b)
(c)
(c)
(d)
(d)
(e)
( f)
(g)
(h)
Forced-ail-cooled,
Directed flow,
(FOA, FOW,
OA/FOA/FOA * * )
(i )
(j )
(k )
(I)
Forced·air·cooled * *
(OA/FA/FA)
(m )
(n)
(p)
(q)
Forced·oil·cooled,
Non·directed flow,
(FOA, FOW,
OA/FOA/FOA * * )
(r)
(s )
(t)
(u )
Self·cooled (OA)
Water-cooled (OW)
Forced-air·cooled*
(OA/FA)
5.2.2.6 Basis for Moderate Sacrifice of Life
in Tables 5(ar-5 (u). Load values in Tables
Following initial load of:
50% 70% 90% 100%
* Ratings 1 33% or less of self-cooled rating
**Ratings greater than 1 3 3% of self-cooled rating
5(a)-5(u) are based on the life expectancy
43
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0>
O1 Z
:-' 00
<L) .....
"" -;:.
Table 5(a)
Capability Table for Normal and Moderate Sacrifice of Life
5 5 ° C Rise, Self-Cooled (OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 50% of Nameplate Rating
�
�
oo t"l
=
.....
Ambient °c
Hours
of
Peak
Load
1
2
1
�
%
2
Hot·
Spot
Tsmp
To r Oi
T� mp
Peak
Load
( Per
Unit )
Hot·
Spot
Ts mp
To r Oi
T�mp
Peak
Load
( Pe r
Unit )
Hot·
Spot
Temp
Top·
Oil
Temp
Hot·
Spot
Tgmp
Top·
Oil
Temp
tC)
98
38
2.00
1 08
48
2.00
118
58
2.00
1 28
68
1 .97
2.00
1 36
1 38
77
78
1.75
2.00
1 34
14B
85
88
Normal
2.00
110
49
2.00
120
59
2.00
130
69
1 .8B
2.00
132
140
77
79
1.70
2.00
1 30
1 50
83
89
1.50
1 .9 1
127
153
89
97
Peak
Load
J
Per
nit)
Hot·
Spot
T!! mp
( C)
Top·
Oil
Temp
t C)
Peak
Load
J
Per
nit)
(oC)
t c)
(Per
Unit )
( C)
( C)
( C)
( C)
0.25
0.50
1 .00
2 . 00
4 . 00
0 . 25
0.50
1 . 00
2.00
4 . 00
0.25
0.50
1 . 00
2.00
4 . 00
0.25
0.50
1 . 00
2.00
4 . 00
0.25
0.50
LOO
2.00
4 . 00
(C)
( C)
(0C)
tij
t"l
t"l
2 . 00
128
67
0.25
0.50
1 . 00
2.00
4 . 00
Normal
24
Peak
Load
2.00
Life
Normal
8
TopOil
Temp
Normal
Normal
4
Hot·
Spot
Temp
50
40
30
Peak
Load
(Per
Unit)
Loss
of
Normal
�
20
10
0
1 .8 9
2.00
1 28
1 38
73
77
1.76
2.00
1 27
148
78
87
1 .6 2
1.91
1.98
1 26
1 50
156
83
94
97
1 .45
1 . 77
1 .86
1 24
148
1 56
87
98
1 02
1 . 27
1.63
1.38
1 .6 3
1 .7 0
119
142
149
86
98
1.23
1 .5 0
117
140
89
1 02
-
1 .0 6
1.38
121
147
92
103
0
c::
.....
t:l
t"l
'"%j
0
::>:I
t""'
74
86
89
1.73
1 .9 5
2.00
122
144
150
1.53
1.72
1 .7 8
1.84
1.91
113
134
141
148
155
73
86
90
95
99
1.43
1.63
1.69
1.75
1.82
113
133
140
1 47
155
77
90
94
98
1 03
1.31
1 .5 2
1 .59
1 .66
111
1 32
1 39
1 46
BO
93
97
1 02
1 . 20
1 .4 2
1 .4 5
110
132
138
B4
97
100
1 .06
1 .3 0
1.35
1 .5 3
1 .5 9
L64
1.70
1 .7 7
98
117
123
129
1 36
144
65
77
81
85
89
94
1.25
1.43
1.49
1.55
1.61
1.68
98
116
1 22
128
1 35
143
69
81
84
88
93
98
1 .l 4
1 .3 4
1 . 39
1 . 45
1.52
1 .5 9
97
116
1 22
1 28
136
143
73
84
88
92
97
101
1.02
1 .23
1 . 29
1 .36
1.43
97
115
121
1 28
1 36
76
88
91
96
100
0.89
1.12
1.19
1 . 26
1.33
1.63
1 .84
1.91
122
143
151
78
90
94
1 .9 0
1 .73
1 .8 1
1 20
142
1 50
82
94
98
�
114
139
92
106
0
>
t:l
Z
0
s::
......
1 09
130
87
1 00
0.91
1.19
106
1 29
89
1
03
-
Z
t%J
::Ii
>
t""'
"
�
96
115
122
1 28
135
80
91
95
99
1 04
-
NOTE: Underlined values, though beyond recommended limits (see 5 .2 .2 .4 ) , are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
• Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3 . 5 ), and must be above zero °C.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.75
1 .00
1 .07
1.15
96
115
121
1 28
83
95
99
103
§:
s::
t%J
::Ii
00
t%J
t:l
'"C
0
:;:
t%J
::Ii
t-3
?:I
>
Z
00
'7J
0
?:I
Table 5(b)
Capability Table for Normal and Moderate Sacrifice of Life
5 5 ° C Rise, Self-Cooled (OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 70% of Nameplate Rating
=
Ambient
0
Hours
of
Peak
Load
o/c
Loss
of
Life
Normal
Peak
Load
(Per
Unit)
2 . 00
Hot-
Spot
Temp
C C)
104
Hot Load Spot
Temp (Per Tem p
(DC)
Unit) (0C)
Top-
Oil
44
Peak
2 . 00
0.25
0 . 50
1 .00
2.00
4.00
!
2
Normal
2.00
115
54
2.00
0.25
0.50
1 . 00
2.00
4.00
1
Normal
..,.
CJ1
0.25
0.50
1 . 00
2.00
4 . 00
2
Normal
0.25
0.50
1 . 00
2 . 00
4 . 00
4
N or mal
0.25
0.5 0
1 . 00
2. 0 0
4 . 00
8
Normal
0.25
0.50
1.00
2.00
4.00
24
114
1 25
E:::
°c
TopOil
Te mp
Peak
54
2 . 00
ee)
64
Load
(Per
Unit)
1 .9 5
2 . 00
Hot- Top· Peak Hot Oil Load Spot
Temp Temp (Per Temp
Unit) c" C )
c"C)
tC)
Spot
1 24
132
135
40
30
20
10
64
73
74
2.00
1.78
2.00
1 34
1 30
145
Top·
Oil
Temp
Peak
Load
(Per
(o C)
Unit)
74
1.81
2 . 00
79
84
1 .56
1 .9 7
l>:l
?:I
00
50
Spot
Temp
(C)
Top·
Oil
Temp
Peak
L ad
(Per
o
Ho Spot
Temp
Temp
133
144
81
84
1.31
2 . 00
117
154
86
94
Hot-
126
1 53
(DC)
85
94
Unit )
1.13
1 . 80
t
(C)
111
151
TopOil
(o C )
87
100
e:
"tj
t-3
0
>-'
0
0
E:::
-<
>
�
t-3
�
01
01
°
0
0
?:I
1.95
2.00
1.70
1.92
1 .9 8
128
131
121
143
150
69
71
74
86
90
1.84
2.00
1 .59
1.81
1.89
127
141
1 20
142
150
74
81
78
90
95
1 .70
1 .9 7
2 . 00
1.47
1 . 70
1 .78
1 .86
126
1 49
151
1 19
141
149
157
79
90
91
82
94
98
103
1 .1, 4
1 .8 4
1 .9 4
1 .33
1.59
1 .6 7
124
148
156
117
140
1 48
84
95
98
85
98
1 02
1 . 34
1 .7 0
1 .16
1 .4 6
120
146
113
138
88
1 00
88
102
0.97
1. 53
0.88
1.31
1 06
143
103
135
87
1 04
87
104
'"
01
°
0
>
-<
l>:l
?:I
>
Q
l>:l
�
......
Z
t:J
1 .5 2
1.71
1 .77
1.83
1 .9 0
112
133
139
147
155
73
86
90
94
99
1.41
1.61
1 .35
1.52
1 .58
1 . 64
1.70
1.76
98
116
1 22
1 29
1 35
143
65
77
80
85
89
93
1. 24
1.43
1.49
1.55
1.61
1 . 67
1.67
1. 7 4
1 . 80
1 11
132
1 39
147
1 54
77
89
93
98
1 02
97
116
68
80
122
84
143
88
93
97
1 28
135
1 . 30
110
1 . 58
1 .64
131
1 38
1 45
1 .51
1.13
1.33
1.39
1.45
1.52
1 . 59
97
115
1 22
128
1 35
143
80
92
97
101
1.17
1.41
1 .47
72
84
88
92
96
101
1.02
1.23
1 .29
1 . 36
1.42
1 09
131
137
96
115
121
1 28
135
83
96
100
1 .0 2
1 . 29
1 .36
76
88
91
96
1 00
0.88
1 .1 2
1.18
1.25
1 .3 2
105
129
1 36
85
99
1 03
0.78
1 .1 6
96
79
91
95
99
103
0.73
0.99
1.06
1.14
115
121
128
1 34
NOTE:
% loss
Underlined values, t h o u gh beyond recommended limits (see 5 .2 .2.4), are given to assis t i n interpolation of the maximum limit.
of life is in addition to normal loss of life.
*Actual water temperature should be 5 D C lower than the ambient temperatures shown above (see 3 . 5 ) , and must be above zero DC.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
98
1 27
95
114
120
127
84
1 02
Z
Q
::0
......
r:n
l>:l
83
95
98
1 03
0
01 >
:-' Z
<0 00
",, -
��
<o l>:l
oo l>:l
>-' l>:l
C"l >
Ol Z
:-" 00
<.0 .....
l>:) "j::;
Table 5 (c)
Capability Table for Normal and Moderate Sacrifice of Life
55 D C Rise, Self-Cooled (OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 90% of Nameplate Rating
"' [i5
�
t>:J
>-'
=
Ambient ° c
"
Hours
of
Peak
Load
!
2
1
>l:>m
%
Loss
of
Life
Normal
2_00
24
not-
jpot
(�C\P
l12
TopOil
Temp
,oC)
51
Peak
Load
( Pe r
Unit)
2.00
1I 0 t -
Spot
Temp
te)
1 22
TopOil
Temp
tC )
61
Hot-
Top-
t C)
Temp
ee)
Peak
Load
(Per
Un it )
Spot
Temp
2.00
132
Oil
71
0. 25
0.50
1 . 00
2.00
4.00
1 21
61
2.00
131
71
0.25
0.50
1 . 00
2.00
4.00
0.25
0.50
1 .00
2.00
4.00
1 .8 9
2.00
1 26
1 36
71
75
1 25
1 46
76
85
40
Hot-
Hot-
Spot
Temp
e Cl
TopOil
Temp
(oC)
1 . 80
2.00
1 30
142
79
81
122
1.81
2.00
1 28
141
76
81
1.56
2_00
1 51
81
91
1 . 59
1 .9 1
1 .98
122
148
155
80
92
95
1 . 38
1.76
1 .8 6
l16
145
1 54
83
96
100
Peak
Load
(Per
Unit)
Spot
Temp
eC)
50
TopOil
Te mp
( C)
Peak
Load
(Per
Unit)
Hot-
Spot
Te m p
(D C )
Top-
Oil
Temp
tC)
2.00
1 52
91
1.75
1 . 98
147
161
98
101
1 .83
1.95
1 49
1 58
97
99
1 . 53
140
101
1 . 59
142
1 00
1 . 34
1 34
1 02
72
1.41
1.66
1.74
1 .82
116
1 39
147
1 55
81
94
99
103
1.22
1.54
1 .6 3
110
138
1 46
83
98
1 02
0.63
1 . 39
81
1 34
1 00
1 .19
128
101
1.92
78
91
95
99
73
85
90
94
99
1.39
1 . 59
1.66
1.73
1 .80
110
1 31
1 38
1 45
1 54
76
89
93
98
102
1 . 27
1 . 49
1.55
1 .63
1 08
1 30
1 37
144
79
92
96
101
1.11
1 . 38
1 .45
1 04
1 28
136
80
95
100
0.81
1 . 25
1 . 33
91
126
134
76
98
102
1 . 08
1.19
121
131
98
104
65
77
80
84
89
9 :1
1 . 24
1 .43
1 . 48
1.55
1 .6 1
1 . 67
97
1 16
1 22
1 25
1 35
143
68
80
84
88
93
97
1.13
1 . 33
1 . 39
1 .45
1.52
1 . 58
119
142
149
1 54
74
87
91
93
U;O
0.25
0.50
1 . 00
2.00
4.00
1 .7 0
1 .7 6
1 . 82
1 . 88
l11
132
1 39
146
154
Normal
1 . 3·1
1 . 52
1 . 58
1.63
1 .70
1.76
97
116
122
1 28
135
143
0.25
0. 5 0
1 . 00
2.00
4 . 00
1.75
2.00
Peak
Load
(Per
Unit)
30
118
141
148
1 56
1 .6 6
1 . 89
1 .95
2.00
0.25
0.50
1 . 00
2.00
4 . 00
Normal
8
'Jnitl
2.00
Normal
4
, Pe r
Normal
Normal
2
i'eak
f--load
20
10
1 .55
1.78
1 .H 5
.....
t>:J
t>:J
t>:J
Cl
e:
.....
t::::l
t>:J
�
0
�
t'"
0
>
t::::l .
....
Z
Cl
E:
......
Z
t>:J
�
>
t'"
"
.....
t'"
96
115
122
128
135
142
72
84
88
92
96
1 00
1 .0 1
1 .22
1 . 28
1.35
1 .4 2
96
115
1 21
128
135
75
87
91
95
100
0.88
1.11
1.17
1 .25
1.32
95
1 14
1 20
1 28
134
79
91
94
99
1 03
NOTE: Underlined values, though beyond re co m men ded limits (see 5 .2 .2 .4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
*Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3 . 5 ) , and must be above zero DC.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.72
0.98
1.05
1.13
94
1 14
1 20
1 27
82
94
98
102
-
�E:
t>:J
�
rll
t>:J
t::::l
"0
�
t>:J
�
0-,3
::0
>
Z
00
"'1
0
::0
==
Table 5(d)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Self-Cooled (OA) and Water-Cooled* (OW) Transformers
Equivalent Load Before Peak Load 100% of Nameplate Rating
=
Hours
of
Peak
Load
%
Loss
of
Life
Normal
1
2
Pea k
Load
Per
nit)
HotSpot
Ts mp
( C)
2 . 00
116
J
TopOil
Temp
(oC)
Peak
Load
(Per
Unit)
HotSpot
Temp
(0C)
55
2.00
126
2.00
125
64
0_25
0 . 50
1.00
2 . 00
4.00
�
2
4
1.92
2.00
1 29
1 35
72
74
HotSpot
T� mp
( C)
1 . 92
2.00
1 31
1 36
TopOil
Temp
(0C)
74
75
Peak
Load
(Per
Unit)
HotSpot
Temp
l . 00
2.00
95
146
t e)
t:':!
40
To r "
Oi
T� mp
( C)
75
85
Peak
Load
(Per
Unit)
HotSpot
Temp
tc )
1 .91
150
50
TopOil
Temp
(C)
Peak
Load
(Per
Unit)
HotSpot
Tl5mp
TopOil
Tem p
1. 72
1 49
102
( C)
tC)
94
124
145
78
84
95
149
1 55
75
92
94
1 . 69
1 . 86
143
155
97
101
-
1 . 50
142
103
72
78
1 .7 0
2.00
1 23
148
77
88
1 . 50
l . 86
1 .95
118
146
154
80
92
96
1 . 00
1 . 69
1 . 80
95
142
151
75
96
100
1.47
1 . 63
1 36
147
99
1 04
0.50
1.31
92
135
85
104
Normal
1 . 64
1.87
1 . 94
2 . 00
118
141
1 49
155
74
87
91
95
1.51
1.76
1 .8 3
1.91
1 16
1 40
147
1 55
77
91
95
99
1 . 34
1 . 63
1 .72
1 . 80
112
1 38
146
154
80
94
99
1
0
3
-
1 . 00
1 . 50
1 . 59
95
135
143
75
97
101
1 . 31
1 . 44
1 29
140
98
1 04
0.81
1 . 10
103
1 29
88
103
1 .48
1 . 69
1 . 75
1.81
1 . 83
110
131
1 38
146
153
72
85
90
94
98
1.37
1.59
1 .6 5
1.72
1.78
108
130
137
145
1 52
75
88
93
97
1 02
1.23
1 .48
1 . 55
1 .62
104
1 29
136
144
77
91
96
100
1 . 00
1 . 36
1.43
1.51
95
127
1 34
142
75
94
99
1
03
-
1 . 34
1.52
1 . 58
1.63
1.70
1.76
97
116
122
1 28
1 35
143
65
77
80
84
89
93
1 . 23
1.42
1 .48
1.54
1.61
1 .67
96
115
122
1 28
135
1 43
68
80
84
88
93
97
1.13
1.32
1 . 38
1 .45
1 . 52
1.58
96
114
121
1 27
135
142
72
83
87
91
96
100
1 .00
9 fi
115
121
1 28
134
142
75
87
91
95
99
1 04
0.25
0.50
1.00
2 . 00
1 . 00
0.25
0.50
1 . 00
2.00
4.00
.....
0
0
==
<
>
::;;
......
:r:
1 . 00
1 .92
2.00
1 25
138
0.25
0.50
1 . 00
2.00
4.00
::0
00
e::
"tI
0-,3
0
0-,3
1.70
2 . 00
1 . 01
2.00
0.25
0.50
l . 00
2.00
4 . 00
Normal
24
65
Peak
Load
(Per
Unit)
30
Normal
Normal
8
TopOil
Temp
(oC)
0.25
0.50
1.00
2.00
4.00
Normal
-l
Ambient °e
20
10
0
01
01
°
C':l
0
::0
O'l
on
°
C':l
>
<
t:':!
::0
>
0
t:':!
::;;
Z
t:I
1.22
1.28
1.35
1.41
1 . 48
Z
1 . 20
1 . 30
1 22
131
95
101
0.94
1.13
110
125
0.86
1 .1 0
94
1 14
1 20
127
1 34
78
90
94
98
1 03
0.70
0.98
1 . 05
1.13
93
113
119
126
1 .17
1.24
1.31
NOTE: Underlined values, though beyond recommended limits (see 5 .2 .2 .4), are given to assist in interpolation of the maximum limit.
% loss o f life is in addition to normal loss o f life.
*Actual water temperature should be 5 °C lower than the ambient temperatures shown above (see 3.5), and must be above zero °e.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
92
101
0
::0
00
......
t:':!
81
94
97
1 02
C':l
01 >
:-> z
� oo
"" ......
��
� t:':!
oo t:':!
.... t:':!
(J �
"" Z
:-' 00
<1:> ....
1>:> -;::'
Table 5(e)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Air-Cooled (OA/FA) Transformers Rated 133% or Less of Self-Cooled Rating
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
�
gj
Ct> t<:I
I-'
=
Ambient °c
Hours
of
Peak
Load
I
2
1
�
00
%
Loss
of
Life
4
24
nit)
2.00
Normal
2 . 00
2.25
0.25
0.50
1 . 00
2.00
4.00
0.25
0. 50
1 .00
2.00
4 . 00
0.25
0.50
1.00
2.00
4.00
N ormal
0.25
0 . 50
1 .00
2. 00
4.00
Normal
8
Load
�Per
Normal
Normal
2
Peak
0 . 25
0.50
1 . 00
2.0 0
4.00
Normal
0. 2 5
0.50
1 . 00
2 . 00
4.00
1.76
1.95
Hot-
Spot
Tg mp
( C)
TopOil
Temp
(oC)
114
40
1 33
1 58
57
67
1 29
151
20
10
0
67
78
Peak
Load
(Per
Unit)
2.00
1.91
2.14
1.66
1.87
HotSpot
Temp
(0C)
TopOil
T�mp
( C)
HotSpot
T�mp
1 34
60
1 33
70
Unit)
1 24
50
2.00
1 34
63
73
1 .8 0
2 .04
1 57
-
1 28
151
71
83
y
Peak
Load
(Per
1.56
1 . 77
( C)
1 57
-
127
1 50
To Oi
Temp
t C)
79
76
87
30
Peak
Load
(Pe r
Unit)
Hot-
Spot
T�mp
( C)
y
40
To Oi
Tgmp
�Per
( C)
Peak
Load
nit)
Hot-
Spot
Temp
(0C)
50
TopOil
T�mp
( C)
Peak
Load
(Per
Unit)
Spot
Temp
Hot·
(0C)
TopOil
Temp
tC l
1.91
1 38
144
68
70
1 .77
2 . 00
137
154
75
80
1.61
1.94
1 36
160
82
88
1 .67
1 32
1 56
75
84
1 . 54
1 .81
131
1 55
81
90
1 . 39
1 . 69
1 28
153
86
96
2.00
1.93
1 . 45
1 . 68
1.74
1 26
149
1 57
80
92
96
1 . 33
1 . 57
1 . 64
124
148
155
85
96
1 00
1 .1 9
1 .46
122
147
89
101
til
t<:I
t<:I
0
c::
....
0
t<:I
'>j
0
::0
t"'
1 . 55
1.73
1.78
1 .84
1 20
142
149
1 57
69
82
86
91
1 .47
1 . 65
1 .70
1 . 76
1 20
1 42
148
1 10
1 30
1 37
144
151
70
82
86
96
115
121
127
1 34
141
62
73
77
81
156
73
86
90
94
1 18
14 1
147
1 . 37
1 . 56
1 .61
1 . 68
1 56
1 .24
1 09
77
90
94
98
1 .27
1 . 47
1 . 53
1.59
1.14
1 . 33
1 . 38
1.44
1.50
1 . 01
118
1 40
147
81
94
98
1.16
1 . 37
1 . 44
116
139
146
85
97
.!.Ql
1 . 03
1 . 27
114
1 38
88
101
0
�
0
....
Z
0
s::
1 54
-
102
1 09
77
89
93
98
102
1 .0 4
1 . 23
1.30
1 08
1 28
135
142
81
93
97
102
0 .91
1.13
1 . 20
106
1 28
134
84
97
101
70
81
84
88
93
97
0.90
95
114
1 20
1 26
1 33
141
74
85
88
92
96
101
0.78
0.99
1 .05
1 .1 2
1 .1 9
95
114
1 20
1 26
1 34
78
89
93
96
1 01
....
Z
t<:I
1.42
1 . 58
1 . 63
1 . 68
1 .73
110
1 30
137
144
151
87
91
1.33
1 . 50
1.55
1 .61
1 . 66
1.30
1.45
96
114
121
1 27
1 34
141
58
69
73
77
81
85
1.21
1.37
1 .42
1.47
1.52
1.57
1.50
1 .55
1 . 60
1 .65
66
78
82
91
95
85
89
1 .5 9
151
74
86
90
94
99
1.12
1 . 28
1 . 33
1 .3 9
1 .44
96
1 14
120
1 27
1 34
141
66
77
81
85
89
93
1.41
1.47
1 .52
1 .50
1 29
1 36
143
1.19
1 . 24
1 .3 0
1.36
1 .4 2
1 29
1 35
143
1 50
95
114
1 20
126
133
141
1 . 36
1 . 09
1.15
1 .21
1.27
1 . 34
NOTE: Underlined values, though beyond recommended limits (see 5 .2 .2 .4 ) , are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
�
�
t"'
0
8
,:..
s::
s::
t<:I
::0
rn
t<:I
0
"d
0
�
t<:I
::0
>-3
Table 5 (f)
Capability Table for Normal and Moderate Sacrifice of Life
55 D C Rise, Forced-Air-Cooled (OAjFA) Transformers Rated 133% or Less of Self-Cooled Rating
Equivalent Load Before Peak Load 70% of Maximum Nameplate Rating
;Ii
>
Z
00
»J
0
;Ii
is:
=
Ambient
10
0
%
Hours
of
Loss
Load
Life
Peak
of
Normal
0.25
0.50
1 . 00
2 . 00
4 . 00
.,..
�
2
4
8
24
Peak
Load
JPer
nit )
2.00
Hot-
Spot
T!imp
( C)
1 20
TopOil
Temp
(0
C)
45
Peak
Load
Per
Unit)
(
2.00
HotSpot
Temp
t C)
1 30
°c
30
20
TopOil
Temp
t C)
55
Peak
Load
(Per
Unit)
1 . 96
2.24
HotSpot
T!imp
( C)
1 38
162
TopOil
Temp
tc)
64
71
Peak
Load
(Per
HotSpot
Temp
1 .B1
2.12
136
1 61
Unit)
t C)
40
TopOil
Temp
tC )
71
78
Peak
Load
JPer
nit)
1 . 65
1 .99
HotSpot
Temp
(o C
)
1 34
160
t:rl
50
TopOil
Temp
(0 C
)
78
85
Peak
nit)
JPer
Load
1 . 38
1 . 84
HotSpot
Temp
(o C
)
126
158
TopOil
Tem p
tC)
84
92
;Ii
00
e
."
>-3
0
.....
0
0
is:
<:
>
::,:j
1.85
2.09
132
155
1 30
1 54
1.45
1.75
Normal
0.25
0.50
1 . 00
2.00
4.00
1 .97
2.19
Normal
0.25
0.50
1 .00
2.00
4.00
1 .7 3
1 .93
1 28
151
6B
79
1.63
1.84
1 27
1 50
72
84
1.53
1 .74
1.81
1 26
149
157
77
88
92
1.40
1 . 64
1 .7 0
1 24
148
155
81
93
96
1.f;:�
1 . 60
121
146
154
Normal
0.25
0.50
1 .00
2.00
4.00
1 . 54
1.71
1.77
1.82
1 20
141
148
1 56
70
82
86
90
1.45
1.63
1 . 69
1.75
1 19
1 40
1 48
1 56
73
86
90
95
1 .35
1 . 55
1 . 60
1 .67
117
1 40
147
1 55
77
90
94
98
1 .2 5
1 .4 5
1.51
1 . 57
l16
1 39
146
1 53
81
94
98
102
1.11
1 . 35
1.42
113
1 38
145
Normal
0.25
0.50
1 .00
2.00
4.00
1 .4 1
1 .57
1 . 62
1 .6 8
1 .73
1 09
1 30
1 36
144
151
66
7B
82
87
91
1.33
1 .49
1.55
1 .60
1 .66
1 09
1 29
1 36
143
151
70
82
86
90
95
1 . 23
1.41
1 .46
1.52
1 . 58
1 08
128
136
143
150
73
85
90
94
98
1.13
1.32
1 . 38
1.43
1 . 50
1 07
1 28
135
142
150
77
89
93
97
1 02
1 . 01
1 . 22
1 . 29
1 . 35
Normal
0.25
0 . 50
1 . 00
2.00
4.00
1.29
1.45
1.50
1 . 54
1 . 60
1 . 65
96
114
121
127
1 34
141
58
69
73
77
81
85
1 . 20
1 . 36
1.41
1.47
1 . 52
1 . 58
95
114
1 20
1 27
1 34
141
62
73
76
81
85
89
1.11
1 . 28
1.33
1 . 39
1 . 44
1 . 50
96
114
120
127
1 34
141
66
77
81
84
89
93
1 .0 1
1 .1 9
1 .25
1 . 30
1 . 36
1.42
95
114
1 20
1 27
133
141
70
B1
85
89
92
97
0.90
] .09
1.15
1 . 21
1.27
1 . 34
1 34
1 57
60
69
133
156
66
75
NOTE: Underlined values, though beyond recommended limits (see
% loss of life is in addition to normal loss of life.
1.73
1 .9 B
72
81
5 . 2 .2.4), are given to
1 .60
1.87
77
86
1 .27
1 28
1 54
83
92
85
1.20
1.61
1 19
151
85
97
114
144
86
101
83
97
101
0.93
1 . 24
107
1 36
84
1 00
106
127
1 34
142
80
93
97
1 01
0.85
1.12
1.18
101
1 26
133
82
96
100
95
1 14
1 19
1 26
133
141
74
85
88
92
97
101
0.77
0.99
1 . 05
1.11
1.18
94
113
119
1 26
1 33
78
89
92
96
101
ill
assist in interpolation of the maximum limit.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
01
01
D
(":I
0
;Ii
1 .06
1 .4 1
97
::3
:::r::
a>
01
°
(":I
>
<:
trl
;:tl
>
0
trl
::,:j
Z
t!..
....
Z
0
;:tl
......
00
trl
�>
:--' Z
"' 00
1.:>
......
, �
..... ......
", trl
oo trl
..... trl
n>
O1 Z
:-J oo
to "" ;:;
Table 5(g)
Capability Table for Normal and Moderate Sacrifice of Life
5 5 ° C Rise, Forced-Air-Cooled (OA/FA) Transformers Rated 133% or Less of Self-Cooled Rating
Equivalent Load Before Peak Load 90% of Maximwn Nameplate Rating
'
=
Ambient °c
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
1
2
0.25
0.50
1 . 00
2 . 00
4.00
Normal
1
Ql
0
0. 25
0.50
1 . 00
2.00
4.00
Normal
2
0.25
0. 5 0
1 . 00
2.00
4.00
Normal
4
0.25
0.50
1 .0 0
2.00
4.00
Normal
8
0.25
0.50
1 . 00
2.00
4.00
Normal
24
0.25
0.50
1 .00
2 . 00
4.00
Peak
Load
Per
nit)
J
Hot·
Spot
T!i mp
( C)
Top·
Oil
Temp
("C)
2.00
2 . 39
--
1 28
162
53
62
1.89
2.13
132
1 56
63
72
1.69
1.89
1.95
1 26
1 49
1 57
20
10
69
80
84
Peak
Load
(Per
Unit)
1 .98
2.27
1.77
2.02
--
1.58
1.79
1.86
Hot·
Spot
Temp
(0C)
Top·
Oil
Temp
(0C)
Peak
Load
(Per
Unit)
Hot·
Spot
T!i mp
( C)
y
To Oi
Temp
t C)
Peak
Load
(Per
Unit)
1 37
161
62
69
1.84
2.15
--
135
161
--
69
76
1.64
2.01
131
68
78
1.64
1.91
129
1 54
74
83
1 .4 6
1.79
155
-
1 25
148
155
73
84
88
1.46
1 . 69
1.76
122
147
1M
77
89
93
40
30
1 . 29
1.59
1.66
Hot·
Spot
Temp
(oC)
TopOil
T� mp
( C)
130
1 59
--
75
83
1 24
78
89
152
-
117
146
ill
79
93
97
Peak
Load
(Per
Unit)
Hot·
Spot
Temp
( 0 C)
50
Top·
Oil
Temp
(oC)
Peak
Load
(Per
Unit)
HotSpot
T8mp
( C)
Top·
Oil
Temp
(oC)
1.86
157
90
1 . 62
I. 79
149
161
95
98
1 .6 4
1 .74
1 49
1
58
-
94
97
1 .4 3
1 . 58
142
154
97
102
142
151
96
1 45
1 . 54
sa
t:<:!
t:<:!
0
c::
0
!Q!.
1.28
1.40
1 36
146
99
1 04
t:<:!
"'l
0
�
t""'
1 . 52
1 . 69
1.75
1.81
118
140
147
155
69
82
86
91
1.43
1.61
1 .66
1.72
117
139
146
1 54
73
85
90
94
1.31
1.52
1 . 58
1 . 64
114
1 38
146
154
76
89
94
98
1.1 8
1 .4 2
1.49
1 . 55
111
1 37
144
1 52
78
93
97
102
1 . 30
1 . 38
134
142
95
100
1.15
1 . 26
1 28
138
96
102
1 .4 1
1 . 57
1.62
1.67
1.72
109
1 29
135
143
1 50
66
78
82
86
91
1.31
1.48
1.54
1 . 59
1.65
1 08
128
1 35
142
1 50
69
81
85
90
94
1.21
1.40
1.46
1.51
1.57
1 . 63
1 06
128
135
142
149
1 58
72
85
89
94
98
103
1.09
1.30
1 . 36
1 .43
1.49
103
126
133
141
149
74
88
92
97
102
1.20
1 . 27
1 . 33
1 25
132
140
91
96
100
1.07
1.15
1.23
121
1 29
1 38
93
98
103
--
1.29
1 . 45
1 . 49
1 .54
1.60
1 . 65
96
114
120
127
1 34
141
58
69
73
77
81
85
1 . 20
1.36
1.41
1.46
1.52
1.57
95
1 14
120
1 26
1 33
141
62
73
77
80
85
89
1.11
1 . 28
1.33
1 .3 8
1.44
1.50
95
114
1 20
1 26
1 33
141
66
77
80
84
89
93
1.01
LIB
1 . 24
1 . 29
1.35
1.42
95
113
1 20
1 26
1 33
140
70
B1
85
88
92
97
0
>
0
Z
0
s::
....
Z
t:<:!
�
>
t;"
0
....
t""'
,!..,
s::
1 .09
1 .1 5
1.21
1.27
1.33
113
120
1 26
133
140
B5
88
92
96
101
NOTE: Underlined values, though beyond recommended limits ( see 5.2.2 .4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
t:<:!
..... t:<:!
�
t:<:!
.....
0.99
1.05
1.11
1.18
113
119
1 26
1 32
89
92
96
1 00
s::
t:<:!
::xl
00
t:<:!
0
'"C
0
�
t:<:!
�
>-3
�
>
Z
00
"'J
0
�
Table 5(h)
Capability Table for Normal and Moderate Sacrifice of Life
55 C Rise, Forced-Air-Cooled (OA/F A) Transformers Rated 133% or Less of Self-Cooled Rating
Equivalent Load Before Peak Load 100% of Maximum Nameplate Rating
0
=
is:
Ambient ° c
10
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
1
2
0.25
0.50
1 . 00
2 . 00
4.00
Normal
1
0. 25
0.50
1 . 00
2.00
4.0 0
Normal
01
I-'
2
0.25
0.50
1 . 00
2.00
4.00
Normal
4
0.25
0 .50
1 .00
2.00
4.00
Normal
8
0_25
0.50
1 .00
2.00
4_00
Normal
24
0_25
0.50
1 . 00
2 . 00
4_00
Peak
Load
Per
J nit)
2_00
L84
2.09
HotSpot
T� mp
( C)
133
131
155
20
TopOil
Temp
tC )
57
64
74
Peak
Load
per
nit)
J
HotSpot
Temp
(o C)
TopOil
Temp
("C)
Peak
Load
(Per
Unit )
1.92
2.22
1 36
161
-
65
72
L73
2.08
--
1.72
1.98
1 29
1 54
-
70
80
1 .5 5
1.86
HotS po t
T� mp
( e)
y
To Oi
Temp
te)
30
Peak
Load
(Per
Unit )
HotSpot
Temp
(0 C)
r
40
(0C)
Peak
Load
( Per
Unit)
HotSpot
Temp
("C)
To Oi
Temp
t:r:J
�
50
TopOil
T� mp
( e)
132
159
--
71
79
L06
1.94
98
ill
70
85
L72
1 50
91
124
153
74
85
1 . 06
1.72
1.82
98
149
1 59
71
90
94
1.53
1 . 67
143
1 55
94
98
Peak
Load
(Pe r
00
Unit)
HotSpot
T� mp
( C)
Temp
1 . 56
1.82
149
1 68
98
103
1 .4 1
143
100
TopOil
(oC )
e::
"0
>-3
0
....
0
0
is:
<:
>
::e
.....
>-3
::c
01
01
0
0
0
�
Q>
1 . 66
1.86
1.93
125
148
1 56
69
80
84
1 . 54
1.77
1.83
1 23
147
1 54
73
85
89
1.39
1 .66
1.73
118
146
1 53
--
76
89
93
1 . 03
L54
1 . 62
97
143
151
-
71
93
97
1 . 38
1.49
1 36
147
95
100
1.50
1 . 68
1 .7 4
1 .80
116
139
1 46
154
69
82
86
90
1.40
1 . 59
1.65
1.71
115
1 38
145
1 53
72
85
89
94
1.27
1.50
1 . 56
1 .6 2
111
1 36
144
152
-
74
89
93
97
1.02
1.39
1.46
1 .54
96
134
142
151
70
91
96
101
-
1.25
1.34
1.43
129
139
148
93
99
1
0
4
--
1 . 40
1 . 56
1.61
1.67
1.72
108
1 29
135
143
150
65
78
81
86
90
1 . 30
1.48
1.53
1.59
1 .64
1. 7 0
1 07
1 28
134
142
1 49
1 57
68
81
85
89
94
99
1.19
1.39
1 .4 5
1 .5 1
1.57
1.62
104
1 27
1 34
141
149
157
71
84
89
93
98
102
L01
1.29
1 .35
1 .42
1 . 48
95
125
1 32
140
148
70
87
92
96
101
1.17
1 . 25
1.32
1 . 39
122
130
1 38
146
90
95
99
1 04
l .09
1 .20
1 24
135
95
102
1.29
1.45
1.49
1.54
1.59
1.65
95
114
1 20
127
133
1 41
58
69
1.20
1.36
1.41
1.46
1.52
1.57
95
113
1 20
1 27
133
140
62
73
77
80
85
89
1.10
1 .2 7
L33
L38
L44
1.50
95
113
120
1 26
133
141
65
77
80
84
88
93
LOO
95
113
119
126
133
140
70
81
84
88
92
96
1.09
1.14
1 . 20
1.27
1.33
113
1 19
1 25
132
140
84
88
92
96
100
1 .04
L11
1.17
118
125
132
92
96
1 00
73
77
81
85
1.18
1 . 24
L30
L36
L41
01
0
1.25
1 .4 2
135
151
99
107
L16
1.30
1 29
144
98
106
Cl
>
<:
t:r:J
�
>
P
t:r:J
::e
.....
Z
I;;j
Z
NOTE: Underlined values. though beyond recommended limits (see 5 .2 _2 .4 ) , are given to assist in interpolation of the maximum limit_
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
P
�
.....
00
t"l
0
01 >
:-" Z
<0 00
t.:> ....
. .... ....
<o t:r:J
oo t"l
.... t"l
0>
O1 Z
:-' 00
"' .!:::'
Table 5(i)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Oil-Cooled ( Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
"" ......
.:.. �
�
trl
.....
=
Ambient °c
Hours
of
Peak
Load
1
1
%
Loss
of
Life
J
nit)
Hot·
Spot
Tl1mp
( C)
Top·
Oil
Temp
( o C)
Peak
Load
Per
nit)
J
H o t·
Spot
Temp
(C)
Top·
Oil
Temp
0
( C)
Peak
Load
(Per
Unit)
Hot·
Spot
Tl1mp
( C)
y
To '
Oi
Temp
tC)
30
Peak
Loa d
(Per
Uni t)
H o t·
Spot
Tl1 mp
( C)
40
50
To rOi
T� mp
( C)
Peak
Loa d
Per
nit)
Hot·
Spot
Temp
Top·
Oil
Temp
Peak
Load
(Per
Spot
Temp
Top·
Oil
T '6mp
J
(C)
(oC)
Uni t)
Hot·
( oC)
( C)
Normal
1.84
2.00
141
1 64
-
46
52
1.77
1.93
140
1 64
53
59
1 . 69
1.86
140
163
-
60
60
1 . 60
1 .7 9
1 39
163
-
67
74
1.51
1.70
138
162
75
81
1 .4 1
1 .6 3
1 38
162
82
88
Normal
1 . 67
1.82
135
1 58
57
66
1 .60
1.75
134
1 57
63
72
1.52
1 . 68
!.§l
1 34
69
78
1.44
1.61
133
1 56
75
84
1 . 35
1 . 53
132
1 55
81
89
1.26
1.45
131
15§
86
95
0. 25
0.5 0
1 . 00
2.00
4.00
0.25
0.50
1
Peak
Load
Per
20
10
0
L OO
Ol
t-:I
Normal
trl
2
8
24
1.29
1 .4 5
1 . 50
1 26
1 48
155
79
89
93
1 . 21
1 . 38
1 . 63
117
138
145
73
84
88
91
1 .18
1 . 33
1 . 37
1.42
117
1 38
145
152
78
89
92
96
1.09
1 . 26
1 . 30
1 . 35
l.18
1 .3 1
1 .3 5
1 .4 0
1 .4 4
1 .4 8
107
1 27
134
141
148
156
69
79
82
86
90
94
1.10
1.24
1 . 29
1 . 33
1 . 38
1.43
108
127
134
140
148
1 56
74
84
87
91
95
99
1 .09
1 .22
1 . 27
1 . 30
1.35
1.39
96
114
1 20
126
134
141
63
72
76
79
82
86
1.01
1.15
1 . 20
1.24
1 . 29
1.33
96
114
120
126
1 33
141
67
77
80
83
87
91
128
150
158
64
74
78
1.45
1.58
1 .63
1 28
149
1 57
69
79
83
1.37
1.52
1.56
1.39
1.52
1.56
1.60
118
139
146
1 53
64
75
78
82
1.33
1 .46
1 . 50
l.54
1 18
1 39
1 46
1 53
69
79
83
87
1.25
1 . 39
1.44
1 .48
Normal
0.25
0.50
l . 00
2.00
4 . 00
1.32
1.44
1 . 48
1.52
1.56
1 . 60
108
1 28
134
141
1 49
157
68
70
73
77
81
85
1.25
l . 38
1.41
1 . 46
1.50
l.54
1 08
127
1 34
141
148
156
64
74
78
82
85
89
Normal
1.23
1.36
1 . 39
1.43
1 . 47
1.50
96
114
1 20
126
1 34
141
53
63
66
69
73
77
1.16
1 . 29
L33
1.37
1.41
1 .4 5
96
114
1 20
1 27
1 34
140
58
67
71
74
78
81
Normal
4
74
84
88
1.51
1.64
1.69
0.25
0.50
1 . 00
2 . 00
4.00
0.25
0.50
1 .00
2.00
4.00
0.25
0. 5 0
1 . 00
2.00
4.00
t;:j
trl
2.00
4.00
127
149
�
�
84
94
98
1.12
1 . 30
1.35
123
146
1 56
83
99
103
115
1 38
144
1 52
82
93
97
101
1 .01
1 . 18
1.23
115
1 37
143
87
98
101
1 . 02
1.17
1.22
1 .27
1.31
1.36
1 07
127
1 33
140
147
155
78
88
92
95
99
103
0.92
1 .09
1.14
1.20
106
126
133
140
82
93
96
100
0.91
1 .07
1.12
1.17
1.22
1.27
95
1 14
120
1 26
1 34
1 40
72
82
85
88
92
96
0.82
0 . 99
1 . 04
1 .09
1.14
1 . 20
96
114
120
1 27
1 33
140
77
87
89
93
97
100
1 25
147
ill
NOTE: Underlined values, though beyond recommended limits (see 5 .2 . 2.4), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
°
*Actual water temperature should be 5 C lower than the ambient temperatures shown above (see 3 . 5 ) , and must be above zero °c.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
(l
c::
....
t::I
trl
"l
0
�
t'"
0
>
t::I
......
Z
(l
s:
......
Z
trl
�
>
t'"
6
F
,:...
s:
s:
trl
�
r:n
trl
t::I
'"d
0
�
trl
�
>-3
:::0
Table 5(j )
Capability Table for Nonnal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Oil-Cooled (Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transfonners
Equivalent Load Before Peak Load 70% of Maximum Nameplate Rating
>
Z
00
"%j
0
:::0
=
Hours
of
Peak
Load
%
Loss
of
Life
No rmal
1
2
0_ 2 5
0.50
1 . 00
2.00
4.00
Normal
0.25
0.50
1 . 00
2 . 00
4.00
Norm al
C)l
W
2
24
1.80
1 .9 7
Spot
T�mp
( C)
140
164
To pOil
Temp
(oC)
49
57
�Load
Pe r
nit)
HotSpot
Temp
(C)
1.73
1 .90
1 40
1 64
TopOil
Temp
(C)
57
63
Peak
Un i t )
HotSpot
T8mp
( C)
1 . 64
1 _82
1 39
163
Load
(Per
TopOil
Temp
(C)
64
70
Peak
Load
(Per
Un it )
HotSpot
Temp
(C)
1.55
1.74
1 38
1 62
s::
y
To Oi
Temp
(0C)
71
77
40
Peak
Load
(Per
Unit)
Spot
Temp
(oC)
1 .45
1 . 66
1 37
161
Hot-
t"l
50
TopOil
Temp
(C)
78
84
Peak
Load
(Per
Unit)
Spot
Temp
(C)
1.31
1.57
1 32
1 60
Hot-
TopOil
Temp
(0C)
84
91
:::0
00
e:::
"tI
>-3
0
....
0
0
s::
<:
::;:;
......
1.64
1.79
1 34
157
59
67
1.57
1.73
1 33
157
65
74
1 . 49
1.66
133
156
71
80
1.40
1.58
131
155
76
85
1 . 30
1 .5 0
1 30
1 54
-
82
91
1.17
1.41
125
1 53
86
97
>-3
::I:
'"
'"
°
C':l
0
:::0
64
75
78
1.39
1.52
1.55
1.59
118
1 39
146
153
64
75
78
82
0.25
0.50
1.00
2.00
4.00
1.31
1.44
1.48
1.52
1.55
1.60
107
128
134
141
148
156
Normal
0.25
0.50
1 . 00
2.00
4.00
1 .23
1.36
1 . 39
1.43
1 .47
1.51
96
114
1 20
1 26
1 33
141
0.25
0.50
1 . 00
2.00
4.00
Peak
30
20
>
127
149
1 56
Normal
8
(lnit)
er
Ho t-
1 . 50
1.63
1.67
0.25
0.50
1 . 00
2.00
3.00
Normal
4
Peak
Load
Ambient °c
10
0
O'l
�
74
85
88
1 .2 7
1 .43
1 .4 8
125
147
155
79
90
93
1.18
1 .3 6
1.41
1 22
146
153
83
95
98
1 .0 6
1 . 27
1.33
119
145
152
87
99
103
1.25
1 . 39
1 .43
1 . 48
1 16
1 38
144
152
73
R4
87
91
1.17
1.32
1.36
1 .4 1
115
137
144
1
51
-
77
88
92
96
1 .03
1 .25
1 . 29
1 . 34
114
1 36
143
151
81
93
96
1 00
0.97
1.16
1.22
111
135
142
85
97
64
74
78
82
85
89
1.17
1.31
1 .35
l . 39
1.44
1.48
107
127
134
141
148
1 .09
l .24
1 . 29
1.33
1.38
1 .4 2
107
127
133
140
147
73
84
87
90
94
98
1 .0 1
1 .1 6
1.21
1 . 26
77
88
91
95
99
103
104
1 24
133
1 30
81
92
96
1 00
0
:::0
00
1 .3 6
106
1 26
132
1 40
1 47
155
0.90
1 . 09
1.14
1.19
.l.Q.Q.
68
79
82
86
90
94
58
67
71
74
78
81
1.09
1.22
1 . 26
1 . 30
l.35
1.39
96
114
1 20
126
1 34
141
63
72
75
79
82
86
1 .0 0
1.15
1 .20
1 .24
1.29
1 . 33
95
114
120
126
133
141
67
77
80
83
87
91
0.91
1 .0 7
1.12
1.17
1 . 22
1 .27
95
1 14
1 20
1 26
1 34
1 40
72
81
85
88
92
96
0.81
0.99
1 .0 4
1 .09
1.14
1 . 20
95
114
1 20
127
133
1 40
77
87
89
93
96
100
C':l
126
149
155
69
80
83
1.35
1 . 50
1.55
1 . 32
1 . 45
1 .49
1 . 54
1 17
138
145
1 52
68
79
83
86
59
70
73
77
81
85
1.25
1.38
1.41
1.46
1 . 50
1.54
107
1 27
1 34
141
1 48
156
53
63
66
69
73
77
1.16
1.29
1.33
1.37
1.41
1 .45
96
114
1 20
127
1 34
1 40
1.43
1.57
1.61
125
1 48
!.QQ.
1 .31
NOTE: Underlined values, though beyond recommended limits (see 5 .2 .2.4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
*Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3. 5 ) , and must be above zero ° C.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ill
'"
°
C':l
>
<:
1:':1
:::0
>
0
1:':1
::;:;
H
Z
a
H
Z
t"l
01 >
:-' Z
0000
t.:>
......
, -
oo t"l
.... ......
oo t"l
..... 1:':1
("»
Ol Z
:-' 00
to ......
"" ;::.
Table 5(k)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Oil-Cooled ( Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 90% of Maximum Nameplate Rating
�
gJ
oo l':!
=
...
Ambient °c
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
0.25
0.50
1 .0 0
2.00
4.00
1
2
Normal
0.25
0.50
1 . 00
2_00
4 . 00
01
Normal
�
(oC)
Hot-
Spot
Temp
CC )
Peak
Load
(Per
Unit)
1.57
HotSpot
T8mp
( C)
To r Oi
Temp
tc)
Peak
Load
(Pe r
Unit )
1 . 74
1.91
1 39
163
54
60
1.66
1.84
1 38
1 62
61
67
1.77
137
162
68
75
1.45
1 . 68
1 . 60
1.76
1 33
156
61
70
1.52
1 . 69
1 32
155
67
76
1 .44
1.61
1 30
1 54
72
1.32
1.53
1 24
147
155
69
80
84
Normal
1.38
1.50
1.55
1.59
116
137
145
152
63
74
78
82
1 . 30
1.44
1.48
1.53
115
1 37
144
151
-
68
79
82
86
Normal
1 . 31
107
127
1 34
141
148
156
59
69
73
77
81
84
1.24
1.37
1.41
1.45
1 . 50
1.54
107
1 27
1 33
140
148
155
96
114
120
126
53
63
66
69
73
77
1.16
1 . 29
1.33
1 . 37
1.41
1.45
96
114
1 20
1 26
1 33
140
0.25
0 . 50
1.00
2.00
1.00
30
20
TopOil
Temp
(DC)
1.40
1.55
1.59
Normal
24
Temp
Peak
Load
(Per
Unit)
65
75
79
0.25
0.50
1 . 00
2.00
4.00
8
Spot
Temp
tc )
TopOil
125
148
156
0.25
0.50
1.00
2.00
4 . 00
4
�
Ho t-
1.47
1.61
1.66
0.25
0.50
1 . 00
2.00
4 . 00
2
Peak
Load
Per
nit)
10
1 . 32
1 .4 8
81
40
To -
y
Oi
Temp
(DC)
74
82
1 . 13
1 . 58
126
77
87
1 .06
1 .44
153
-
Hot-
Spot
Temp
("C)
111
1 58
1 08
150
50
TopOil
Temp
t C)
76
88
77
92
Peak
Load
(Per
Unit)
HotSpot
Temp
(oC)
TopOil
Temp
(DC )
1.45
153
94
1.31
1.41
145
156
97
101
1 .32
1 . 38
104
143
151
76
94
98
75
88
91
95
0.95
1.23
1 . 27
1 . 33
1.38
99
1 34
141
149
1 57
74
92
95
99
1 04
1.12
1 .19
1 . 25
1 29
138
147
94
99
103
1 39
147
155
71
83
87
90
94
98
0.92
1.16
1.20
1.26
1.30
1 . 36
96
125
131
1 39
1 46
72
87
91
95
99
103
1 .05
1.12
1.18
1.23
1 22
130
1 38
146
90
95
99
103
95
114
1 20
1 26
1 33
140
67
77
80
83
87
91
0.91
1 .0 7
1.12
1 .1 6
1 . 21
1.27
95
114
1 20
1 26
1 33
140
72
81
85
88
92
96
0 .8 1
0 .9 8
1 .0 4
1 .09
1.14
1 . 20
95
113
1 20
1 26
1 33
140
77
86
89
93
96
100
74
85
88
1.22
1.41
1.45
119
145
152
78
90
93
1 .2 3
1.38
1.42
1.46
114
136
144
1
51
-
72
83
87
91
1.13
1.30
1.35
1 .4 0
111
1 35
142
150
64
74
77
81
85
89
1.16
1 . 30
1.35
1 . 39
1 .44
1.48
106
1 26
1 33
140
68
79
1 04
126
1 48
155
86
90
94
1.07
1.23
1.28
1 . 32
1 . 38
1 .42
58
67
71
74
77
81
1 . 09
1.22
1 .26
1 .30
1.35
1.39
96
114
1 20
126
133
141
63
72
75
79
82
86
1.00
1.15
1.19
1.24
1.28
1 .33
1 .52
Peak
Load
(Per
Unit )
1 33
1 60
123
146
153
1 .00
1.20
1 .2 8
137
148
97
102
......
l':!
l':!
l':!
0
c::
......
tj
l':!
""1
0
�
t"'
1.43
1 .47
1.51
1.55
1.59
1 . 23
1.36
1.39
1.43
1.47
1.51
133
141
82
1 33
�
are given to assist in interpolation of the maximum limit.
Underlined values, though beyond recommended limits (see 5 . 2 . 2 .4 ),
% loss of life is in addition to normal loss of life.
* Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see
NOTE:
HolSpot
Temp
t C)
3 . 5 ),
and must be above zero D C.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0
>
tj
......
Z
0
s:::
......
Z
l':!
�
>
t"'
0
?
.:...
s:::
s:::
t:J
�
CIl
t:J
tj
'"
0
::;:J
l':!
�
>-3
::>:l
:>-
Table 5(1)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Oil-Cooled ( Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 100% of Maximum Nameplate Rating
Z
00
"'1
0
=
Ambient DC
Ho ur s
of
Pea k
Load
%
Loss
of
Life
N o r m al
!
2
0.25
0.50
1 . 00
2 . 00
4 . 00
Normal
0.25
0.50
1 . 00
2 . 00
4 .00
Ql
Normal
Ql
2
0.25
0.50
1.00
2.00
4 . 00
Normal
4
0.25
0.50
1 .00
2.00
4 .0 0
Normal
8
0 . 25
0.50
l . 00
2.00
4 . 00
Normal
24
0 . 25
0.50
l . 00
2 .00
4 .00
Pea k
Lo a d
�Per
nit)
1 .7 1
1 . 88
l .57
1 .73
Hot·
Spot
T�mp
( C)
138
162
131
155
1 .46
1 24
1 .6 0
1 .64
147
154
1 .3 7
1 .5 0
1 .54
1 . 58
Top·
Oil
Temp
(DC)
57
63
62
71
65
76
79
Peak
(Per
Hot·
Spot
Temp
1 .6 2
1 .R O
1 37
161
Load
Unit)
1 .4 9
1 .66
1 .38
1 .53
1 .5 8
1 15
137
1 44
152
81
1 . 52
1 . 55
l . 59
1 06
1 26
1 33
140
148
156
59
69
73
76
80
84
1 . 23
l .35
1 .3 9
1 .4 3
l .47
1.51
96
1 14
120
1 26
133
14 1
53
62
66
69
73
77
63
74
77
1 .30
1 .44
(D C)
130
154
-
122
146
153
-
To pO il
Temp
Pea k
Loa d
TopO il
Te mp
40
Peak
Load
(P e r
Un i t )
Temp
t C)
T� mp
( C)
(Per
Hot·
Spot
T�mp
63
70
1.50
1 .73
133
160
70
77
1 . 00
1 .6 3
95
1 58
67
68
77
1 .38
1.59
125
72
83
1 .00
1 .4 9
95
150
67
88
tC)
69
80
84
Unit)
1 .28
1 .4 6
1.51
1 14
136
143
151
-
67
79
82
86
l . 20
l .3 7
1.41
1.16
1 .23
l .37
141
145
1 .4 9
l . 54
1 06
1 26
132
14 0
147
1 55
63
74
l .16
l . 29
1 .33
l . 37
1 .4 1
1 .4 5
95
114
120
1 .18
30
20
10
0
( C)
153
-
119
145
1 52
t C)
73
85
88
1 . 00
1 .38
1 .43
1 .00
l .29
Hot·
Spot
95
142
151
95
TopOi l
84
67
89
93
67
150
70
83
87
91
l.15
1 .3 0
1 .34
l . 39
1 .43
1 .4 8
1 04
1 26
132
139
147
154
67
78
82
85
89
93
1 .0 0
1 . 23
1 .27
1.32
1.37
1 .42
95
1 25
132
1 39
1 46
1 54
83
86
90
94
98
1 . 09
1 . 22
1 . 26
1 . 30
1 .35
l . 39
96
114
120
1 26
133
140
63
72
75
79
82
86
1.00
95
1 14
120
1 26
1 33
140
67
77
80
83
87
91
111
135
143
1 33
87
l .3 9
l .4 4
141
1 49
1
57
-
91
95
99
67
1 .34
�t:J
Peak
Load
(Per
Unit)
1 . 49
Hot·
Spot
Temp
tC)
TopOil
Temp
t C)
] 52
1.37
l .4 5
144
1 .27
1 . 34
l .4 1
1 :17
1 47
155
::>:l
00
50
89
92
96
Hot·
Spot
T� mp
TopOil
Temp
1. 4 1
152
97
1 . 28
1 .4 2
144
161
98
1 04
0.50
l .19
1 .30
76
137
152
60
97
1 04
Peak
Load
(Per
Unit)
( C)
(DC)
c:::
"d
>-3
0
>-'
0
0
s:::
<:
:>::E
I-<
>-3
:r:
01
01
°
(')
0
::>:l
a>
01
1.19
l.26
1 .31
1.38
156
129
139
147
156
92
97
101
89
94
98
1 03
0.75
l .1 3
1 .2 2
90
130
143
76
95
101
°
(')
:><:
t:J
::>:l
:>0
t:J
::E
I-<
Z
t:l
....
Z
1.30
l .43
l .4 7
l.51
77
81
85
89
1 26
58
67
71
74
133
140
81
77
1.15
1 .19
1 . 23
l . 28
l .33
1.13
1.19
1 .25
l .30
1.35
0.91
1 . 07
1.12
1 . 16
l . 21
1 . 27
1 22
1 29
13R
146
154
86
90
94
98
102
0.94
1 . 08
1.16
1.22
1 08
1 25
135
144
94
114
71
81
85
88
91
96
0.80
0.98
1 .0 4
1 .09
l.14
1 .20
94
113
1 19
1 26
133
140
120
126
132
140
NOTE: U nderl i ned values, though beyond recommended limits (see 5 .2 .2.4), are given to assist in interpolation of the maximum limit.
% l oss of life is in addition to normal loss of life.
*Actual water temperature should be 5 D C lower than the ambient temperatures shown above (see 3.5), and must be above zero D C.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
83
92
97
lQe.
76
86
89
93
96
1 00
0
::>:l
....
00
t:J
(')
01 :>-
:-> Z
0:> 00
t<> ....
� t:::i
0:> t:J
oo t:J
.-. t;r1
n ;l>
<:i' Z
:-' 00
.., ......
t-:> -;::;
' t:IJ
Table 5(m)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise , Forced-Air-Cooled (OA/FA/FA) Transformers Rated Over 1 33% of Self-Cooled Rating
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
� t:IJ
oo t:IJ
I-'
=
Ambient °c
Hours
of
Pea k
Load
I
'2
c;n
�
2
%
Loss
of
Life
Normal
0.25
0.50
1 .00
2 .00
4 .00
1 . 84
2 . 04
Normal
0.25
0.50
1 .00
2 .00
4 .00
1 .6 2
1 .8 0
0.25
0.50
1 . 00
2 .00
4 .00
0.25
0.50
1 . 00
2 .00
4 . 00
Normal
0.25
�4
JPer
nit)
2 .00
Norm al
8
Load
Normal
0.25
0.50
1 . 00
2.00
4.00
N orm al
4
Pea k
O liO
1 . 00
2 . 00
4 . 00
HotSpot
T( � mp
C)
1 33
135
159
TopOil
Temp
(0
C)
48
61
71
P ea k
Load
(P
e
r
Unit)
HotSpot
Temp
(o
C)
TopOil
Te mp
("C )
Peak
Load
(Per
Unit)
1 .97
2.21
140
1 64
57
64
1 . 87
2.1 1
1 .7 4
l .9 5
134
1 58
66
76
1 .6 4
1 .85
HotSpot
T( �mp
C)
Top Oil
Temp
o
( C
)
Peak
Load
(Per
Unit)
HotSpot
Temp
(o
C)
40
TopOil
Temp
(0
C)
Pe a k
Load
(Per
Unit)
Hot-
Spot
Temp
("C)
50
TopOil
Temp
(0
C)
Peak
Load
(Per
Unit)
HotSpot
Temp
TopOil
(0
Temp
tC )
C
1 6:,
63
71
1 .7 6
2.00
139
163
70
78
1 . 63
1.89
138
162
76
84
1 .5 0
1 .78
1 36
161
83
91
133
1 57
71
82
1 .54
1 .7 6
132
1 56
77
87
1 .43
1 .6 6
132
155
82
92
1.30
1.55
130
1 54
87
97
1 39
)
......
t:IJ
t:IJ
t:IJ
Q
1 27
150
67
79
1.54
1.72
1 .7 7
1 27
149
157
71
83
87
1 .45
1 .6 3
1 .6 9
1 26
149
1 56
76
87
91
1 .3 5
1 . 54
1 .6 1
1 25
148
1 55
80
91
95
1 . 24
1 .45
1 .52
1 24
147
1 55
84
96
100
1.1 3
1 .36
1 22
146
88
1 00
C
......
t:J
t:IJ
"'j
0
�
t"'
1 . 5 :1
1 . 58
1 16
1 :1 8
145
152
74
86
90
94
1.21
1 . 39
1 . 45
1 .50
1 16
138
145
151
78
90
94
98
1.12
1 . 30
1 . 36
1 .42
115
137
144
151
82
94
98
102
1 . 00
1 .21
1.28
113
1 36
143
86
91l
1 02
65
76
80
84
88
93
1.21
1 . 37
1 . 42
1 . 48
1.53
1 . 59
107
1 27
133
141
148
155
69
80
84
88
92
97
1.12
1 . 29
1 . 35
1 40
1 . 46
1 . 52
106
1 27
133
140
148
1 55
73
85
88
92
96
101
1 . 02
1.21
1 .2 6
1 .32
1 . 38
1 06
1 27
133
140
148
77
89
92
96
0.91
1.11
1 .1 7
1 .23
105
1 26
1 32
140
81
93
96
101
58
68
72
76
79
84
1.11
1 .26
L3 2
1 .3 7
1 .4 2
1 .4 8
95
114
1 20
1 26
133
140
63
73
76
80
84
88
1 . 01
1.18
1 .23
1 .28
1 . 34
1.4 0
95
114
1 20
1 26
133
140
67
77
81
84
88
92
0.90
1 . 09
1 .1 4
1 . 20
1 .26
1.32
95
113
1 19
1 26
133
140
71
81
85
88
92
96
0.78
0.98
1 .0 4
1.11
1 . 17
1 .23
95
113
1 19
1 26
1 :13
140
76
86
89
93
97
101
1 .6 3
1 .68
l .7 3
1 18
139
146
153
66
78
82
86
1 .3 9
1 . 55
1 .6 1
1 .6 6
117
138
146
152
70
82
86
90
1 . 30
1 .4 7
l . 38
1 .53
1 . 58
1 .63
1 . 68
1 .7 3
1 07
1 27
134
141
148
1 56
61
72
76
80
84
119
1 .3 0
1 .4 6
1 .50
1 .6 1
1 . 66
1 07
1 27
1 33
140
148
1 56
1 .28
1 . 4 :>
1 .47
1 .52
1 .57
l .B 2
96
1 14
1 20
1 26
133
140
54
64
68
71
75
79
1 . 19
1 .35
1 . 39
1 .44
1 .4 9
1 . 55
95
114
1 20
1 26
133
140
1 .48
0
;I>
t:J
Z
Cl
s::
......
Z
t:IJ
U, 5
NOTJ<.;; Underlined values, though beyond recommended
is in addition to normal loss of life.
% loss of life
30
20
10
0
limits (see
5_2.2.4 ), are given
to
ill
assist in interpolation of the maximum limit.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
�
;I>
t"'
6
F
,:...
s::
s::
t:IJ
�
00
t:IJ
t:J
"C
0
::E
t:IJ
::tI
>-3
�
>
Z
Table 5(n)
Capability Table for Nonnal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Air-Cooled (OA/FA/FA) Transformers Rated Over 133% of Self-Cooled Rating
Equivalent Load Before Peak Load 70% of Maximum Nameplate Rating
00
"lj
0
::0
=
0
Hours
of
Peak
Load
1
2'
Cl1
-;J
2
4
8
24
%
Loss
of
Life
Peak
Load
Per
�
1 nit)
Normal
0.25
0.50
1 . 00
2.00
4.00
2.00
Normal
0.25
0.50
1 . 00
2.00
4 . 00
1.81
2.00
Normal
0.25
0.50
1 .00
2.00
4.00
1 .61
1 .78
1 . 83
tc)
1 40
Top-
Oil
Temp
(o e )
53
Peak
Load
(Per
ni )
U t
1 .9 2
2.16
HotSpot
Temp
(oC)
1 39
1 63
20
Top-
Oil
Temp
t C)
60
68
1 34
157
62
72
1.71
1 .9 1
1 33
156
68
78
U
un
2 .0 6
HotSpot
T�mp
( e)
1 38
1 63
To p·
Oil
Temp
(oe)
66
74
Peak
Load
(Per
HotSpot
Temp
1.69
1 .95
1 37
1 62
Unit)
(o C )
Top·
Oil
Temp
tC)
73
81
Hot-
Peak
Load
(Per
Uni t )
Spot
Temp
1 . 54
1 . 83
135
1 60
(C)
5:
tzl
�
50
Top·
Oil
Temp
(oC)
79
87
Peak
Load
(Per
Unit)
Hot·
Spot
T5m p
1.35
1.71
1 29
159
( C)
00
Top·
Oil
Temp
(oC )
84
93
e::
'1:1
>-3
0
>-'
0
0
5:
<:
1 . 60
1 .8 2
132
156
73
83
1 .49
1.72
131
155
78
88
1 . 36
1.62
129
1 54
83
94
1.17
1 .50
121
152
85
98
�
......
>-3
:::r:
'-"
'-"
0
(")
0
�
1 .4 6
1.63
1.67
1.73
Normal
0.25
0.50
1 .00
2 . 00
4 . 00
1 . 38
1.53
1.57
1.62
1 . 67
1.73
1 27
149
1 57
67
79
83
1 .5 2
1 .7 0
1.76
1 26
148
1 S6
71
R :l
87
1.42
1.61
1 . 67
1 25
148
155
116
1 37
144
152
1.38
1.55
1 . 60
1.65
116
138
145
152
69
81
86
89
1 . 29
1 . 47
1 .52
1 . 58
61
72
76
80
84
89
1 . 29
1.45
1.50
1.55
1 . 60
1 6 fi
1 07
1 27
1 33
141
148
156
65
76
80
84
88
9 :1
1 . 20
1 . 37
1 .42
1 . 47
1 .53
l S9
106
1 26
133
140
1 48
1 55
54
64
68
71
75
79
1 . 19
1.35
1 .40
1.44
1.50
1.55
1 14
95
58
68
72
76
80
84
1 . 10
1 . 26
1.31
1.37
1 . 42
9 1)
113
1 20
126
132
1 40
117
1 38
145
153
65
77
81
86
107
127
133
141
148
1 56
76
H7
91
73
85
89
94
1 .32
1 .5 2
1 .59
1 23
147
1 54
80
92
96
1 . 20
1 . 43
1 . 50
1.19
1 . 38
1 .44
1 . 50
111
137
144
151
77
90
94
98
1 . 09
1 . 29
1 . 35
1.41
1 21
145
154
83
96
100
1 . 04
1.33
113
1 36
143
1 50
81
93
97
102
0.93
1.19
1 . 26
1 15
144
85
100
a>
'-"
0
(")
>
<:
tzl
�
108
134
142
82
97
101
>
CJ
tzl
�
......
Z
t:l
12R
1.42
1.47
1.52
1 . 57
1.62
95
113
119
126
1 33
140
1 20
1 26
1 33
140
NOTE: Underlined values, though be yond recommended limits
loss of life is in addition to normal loss of life.
%
Peak
Load
(Per
ni t )
40
30
>
Normal
0.25
0 . 50
1 . 00
2 . 00
4 . 00
Normal
0 . 2S
0.50
l . OO
2 . 00
4 . 00
HotSpot
Tem p
Ambient °c
10
1.17
88
92
97
1.11
1 . 28
1.34
1 . 40
1 .46
1 S1
106
126
132
1 40
147
1 55
73
84
88
92
96
101
1 .01
1 .20
1.25
1.32
1 . 38
lOS
1 26
132
140
1 47
77
88
92
96
1 00
0.R6
1 .10
1.16
1 . 22
101
1 24
132
139
79
92
96
1 00
63
73
76
80
83
88
1 .01
1 . 18
1 . 23
1 . 29
1 . 34
1 . 40
95
113
119
1 26
132
140
67
77
80
84
88
92
0 .90
1 .0 8
1.14
1 .2 0
1.26
1 .31
95
113
119
125
133
1 39
71
81
85
88
92
96
0.78
0.98
1 . 04
1.11
1.17
1.23
94
1 13
1 19
1 26
1 33
1 40
75
86
89
93
97
1 00
69
80
H4
(see 5 .2.2.4 ) , are given to assist i n interpolation of the maximum l imit.
Z
CJ
�
FiJ
tzl
(")
'-" >
:-' Z
"' 00
"" ......
��
", tzl
oo tzl
...... tzl
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
C':l ;'c.n z
:-' 00
to .....
"" ;::.
Table 5(p)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Air-Cooled (OA/FA/FA) Transformers Rated Over 1 33% of Self-Cooled Rating
Equivalent Load Before Peak Load 90% of Maximum Nameplate Rating
�
�
oo tzl
....
=
Ambient ° c
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
I
2
0.25
0.50
1 . 00
2 . 00
4.00
Normal
1
I:.l1
00
0 . 25
0.50
1 . 00
2.00
4 . 00
Normal
2
0.25
0.50
1 . 00
2.00
4.00
Normal
4
0.25
0 . 50
1 .00
2.00
4 . 00
Normal
8
0.25
0.50
1 . 00
2.00
4.00
Normal
24
0.25
0.50
1 . 00
2.00
4.00
Pe ak
Load
Per
nit )
Ho t·
Spot
T!/mp
( C)
Top·
Oil
T�mp
( e)
1 .96
2.19
139
163
1.75
1.96
�
133
J
1 . 58
1 .7 6
1 .81
125
148
1 56
20
10
Peak
Load
Per
nit)
Hot·
Spot
T�mp
57
65
1 .84
2.09
1 38
162
64
71
1.72
1.98
64
74
1.65
1 .87
131
1 56
69
80
1.53
1 .7 7
67
79
83
�
1 .49
1.67
1.73
( C)
1 24
1 47
1 55
--
TopOil
T�mp
( e)
71
83
87
Peak
Load
(Per
Unit)
1 . 38
1 . 58
1 . 65
Hot·
S po t
T!/mp
( e)
,
30
To Oi
Temp
t e)
Peak
Load
(Per
Unit)
1 37
161
70
78
1 . 56
1 .8 6
1 32
160
1 29
74
85
1 .38
1 .66
�
1 25
ll.!
122
1 46
1 54
75
87
92
1 .24
1 .49
1 . 56
Hot·
Spot
T� mp
( C)
117
144
152
,
40
,
50
Peak
Load
(Per
Unit )
Hot·
Spot
Temp
t e)
To Oi
Temp
0
Peak
Lo ad
(Per
Unit )
Hot·
Spot
T�mp
( e)
Top·
Oil
Temp
e e)
75
84
1 .7 3
157
90
1.54
1 50
95
78
90
1 . 54
150
94
1 . 36
1.49
To Oi
T�mp
( e)
77
91
96
1 . 38
1 . 45
142
1 50
( C)
95
99
1.23
1 .34
143
97
155
-
102
--
135
147
96
103
.....
tzl
tzl
tzl
P
c::
.....
t:!
tzl
""l
0
:Xl
t'"
1 .46
1.61
1 . 66
1.71
116
137
144
151
65
77
81
85
1.37
1 . 54
1 . 59
1 . 64
115
1 37
144
1 51
69
81
85
89
1 . 27
1.45
1.51
1 . 56
113
1 36
143
1 50
72
85
89
93
1.15
1 . 37
1.42
1.48
1.55
110
135
142
1 49
158
75
89
93
97
102
1 . 26
1 .33
1 .4 0
1 . 37
1.53
1 . 57
1.62
1 .6 7
1 .72
1 07
1 27
133
140
148
1 55
60
72
76
79
84
88
1 . 29
1 . 44
1.50
1.55
1.60
1.66
1 06
1 26
133
1 40
148
1 55
64
75
79
84
88
92
1 .2 0
1.37
1 .4 2
1 .47
1 .53
1 .5 8
105
126
132
140
147
155
68
80
83
88
92
96
1 .0 8
1 . 28
1.33
1 . 39
1.45
1.51
103
125
131
1 39
146
1 54
71
84
87
92
96
1 00
1 . 18
1 . 24
1.31
1 . 37
1 24
1 31
1 39
1.28
1 .4 2
1.47
1 .52
95
113
119
126
1 32
140
54
64
67
71
75
80
1.19
1 . 34
1 . 39
1 .4 4
1 .4 9
1.55
95
113
1 19
126
1 32
1 40
58
68
72
75
79
83
1.10
1 . 26
1 .31
1.37
1 .42
1.47
95
113
119
1 26
133
140
62
73
76
80
84
88
1.00
1.18
1.23
1 . 29
1 . 34
1.40
94
113
119
1 26
132
140
66
77
80
84
88
92
1 . 08
1.14
1.19
1 .2 5
1 . 32
1 . 57
1.62
132
141
1 49
92
96
101
1.13
1 .22
1 . 30
1 28
137
147
94
99
104
0
;.t:I
.....
Z
0
s::
.....
Z
tzl
146
87
91
96
1 00
1 . 05
1.14
1.21
1 . 28
1 20
1 29
137
145
90
95
99
104
113
119
125
1 32
140
81
85
88
92
96
0.99
1.04
1.11
1.17
1.23
113
119
126
1 32
140
86
89
93
96
101
NOTE: Underlined values, though beyond recommended limits (see 5.2.2.4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
:Xl
;.t'"
"
t'"
�s::
tzl
�
tzl
t:I
"C
0
:::1
tzl
:Xl
...,
�
�
Table 5(q)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Air-Cooled (OA/FA/FA) Transformers Over 133% of Self-Cooled Rating
Equivalent Load Before Peak Load 100% of Maximum Nameplate Rating
til
":1
0
�
is:
l'l
�
=
Ambient
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
!
2
0.25
0.50
1 .00
2.00
4 . 00
Normal
1
01
CO
0.25
0.50
1 .00
2.00
4.00
Normal
2
0.25
0.50
1 . 00
2.00
4 . 00
Normal
4
0.25
0.50
1 .00
2.00
4 . 00
Normal
8
0.25
0.50
1 . 00
2.00
4 . 00
Normal
24
0.25
0.50
1 .00
2.00
4.00
Peak
Load
iJPer
nit)
1.91
2.15
Hot·
Spot
T� mp
( C)
138
162
10
Top·
Oil
Temp
(C)
59
67
Peak
Load
(Per
Unit)
1.79
2.05
--
Hot·
Spot
Temp
e C)
1 36
161
til
°c
20
TopOil
Temp
(oC)
65
73
Peak
Load
(Per
Unit)
Hot·
Spot
Tsmp
1 . 63
1 . 93
132
160
( C)
y
To Oi
Temp
C C)
71
80
30
40
Peak
Load
(Per
Unit)
Hot·
Spot
Temp
TopOil
Temp
1 .06
1 .8 0
99
1 57
C C)
(C )
Peak
Load
(Per
Unit)
Hot·
Spot
Temp
(DC)
68
86
1 .63
152
c::
"C
50
Top·
Oi l
Tsmp
( C)
Unit)
(Per
Hot·
Spot
T� mp
( C)
1 . 50
151
Peak
Load
TopOil
T'6m p
( C)
91
97
...,
0
....
0
0
is:
<:
>
::a
=3
::c
1 .7 2
1 . 93
131
156
-
65
75
1 .6 1
1.83
1 30
1 54
-
70
80
1.47
1 .73
125
153
74
85
1 . 06
1 .62
99
150
68
90
01
01
1 . 45
1 . 57
144
156
93
98
°
1 . 3 -1
1 .5 1
143
1 59
98
105 ·
n
0
�
a>
01
°
1.56
1.74
1 . 80
124
147
155
67
79
83
1.46
1 . 66
1.71
1 22
1 46
153
71
83
87
1 . 34
1 . 56
1 . 63
118
1 44
152
73
87
91
1 .03
1.46
1 . 54
97
142
151
68
91
95
1.45
1.61
1 . 66
1.71
115
1 37
143
151
64
77
81
85
1.35
1.53
1 . 58
1 .63
113
136
143
1 50
68
81
84
89
1 . 24
1.45
1.50
1.56
110
135
142
1 50
71
84
88
93
1 .02
1 . 34
1 .41
1 .48
1 . 54
96
1 32
141
1 49
157
1 . 37
1.52
1.57
1 .62
1.67
1.73
1 06
126
133
140
147
156
60
71
75
79
83
88
1.28
l.45
l.49
1 . 55
1 . 60
1.65
105
1 26
1 32
1 40
1 47
155
64
76
79
83
88
92
l . 28
1 .4 2
1 .47
1.52
1 . 57
1 . 62
95
113
1 20
126
1 33
140
54
64
68
71
75
79
1.19
1 . 34
1 . 39
1 .44
1 . 49
1 . 54
95
113
1 19
126
132
1 40
58
68
72
75
79
83
1 .1 7
1 .31
1 .42
1 . 50
135
147
157
92
98
103
1.22
1 . 38
135
152
97
1 06
67
87
92
97
101
1.22
1 .30
1 .38
1 28
138
146
89
95
100
1.14
1.27
1 29
1 43
94
102
l .1 6
1 . 23
1 . 30
1 . 36
121
129
137
146
86
90
95
1 00
1 .09
1.19
1 .27
1 24
135
144
92
98
103
1 .08
1.13
1 . 20
1 .25
1 . 31
113
118
1 25
132
139
81
84
88
92
96
1 .04
1.10
1.16
1 .23
118
1 25
132
1 39
89
92
96
100
1 .36
1 .41
1.46
1.52
1 .58
103
125
132
1 39
147
1 54
67
79
83
87
92
96
1 .0 1
1 . 27
1 . 33
1.38
1.45
1 . 50
95
1 24
131
1 38
1 46
1 54
67
83
87
91
96
100
1.10
1 .2 6
1.31
1.37
1 .4 2
1 .4 8
95
113
119
1 26
133
140
62
73
76
80
84
88
1 .00
1.17
1.23
1 . 28
1.34
1 . 39
95
113
119
1 26
133
140
67
77
80
84
88
92
NOTE: Underlined values, though beyond recommended limits (see 5.2 . 2 .4 ), are given to
% loss of life is in addition to normal loss of life.
assist in interpolation of
n
>
<:
l:IJ
�
>
0
l:IJ
::a
Z
9
Z
the maximum limit.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0
�
53
l:IJ
n
01 ):-' Z
([) tIl
�
.....
, �
.... .....
([) l:IJ
oo l:IJ
.... l:IJ
0 ;'-
"" Z
;--1 00
Table 5(r)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Oil-Cooled (Non-Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 50% of Maximum Nameplate Rating
\0 ....
� -;::.
' t<J
....
t<J
�
t<J
....
=
Hours
of
Peak
Load
%
Loss
of
Life
Nor ma l
Peak
Load
�Per
t: n i t )
2.00
1.80
1.97
Hot -
Sp ot
T� mp
( C)
To yOi
Temp
(C)
0.25
0.50
1 . 00
2 . 00
4 . 00
Normal
en
0
2
0.25
0.50
1 . 00
2.00
4 . 00
Nor m al
4
0. 2 5
0.50
1 . 00
2.00
4 . 00
Normal
8
0.25
0 . 50
1 . 00
2 . 00
4.00
Normal
24
NOTE:
0.25
0. 5 0
1.00
2.00
4 . 00
(Per
Unit)
1 37
1.95
2.16
1 36
1 58
64
75
1.71
1.90
Hot-
Spot
Temp
( oC )
TopOil
Temp
t C)
Pea k
Load
(Per
U n it )
Hot-
Spot
Tsmp
( C)
40
30
To y Oi
Temp
t e)
Peak
Load
(Per
Unit)
Hot-
Spot
Temp
t e)
TopOil
Temp
t e)
140
165
59
68
1.85
2.07
140
163
66
74
1.74
1.97
1 :39
1 63
72
80
1 35
1 58
69
80
1 .62
1.81
134
157
74
85
1 . 52
1.72
1 33
156
78
90
Peak
Load
(Per
Unit)
Ho t -
Spot
Temp
(C)
1 .62
1.87
1 38
163
1 . 42
1 . 64
132
156
50
To pOil
Temp
( oC)
Pea k
Load
(Per
U n it)
Hot-
Spot
Temp
("C )
To p Oil
Temp
eC )
78
86
1 . 50
1 .76
137
161
84
92
83
95
1.30
1 . 53
131
155
88
99
....
t<J
t<J
t<J
1 .59
1.74
1 28
1 50
69
82
1.51
1.67
1 28
1 50
73
86
1.43
1.60
1 . 65
1 27
149
157
1 . 44
1.59
1.63
1 .68
118
140
146
1 54
68
81
85
89
1.37
1.52
1 . 56
1.61
1 18
1 39
145
1 53
71
84
88
93
1 .29
1 .44
1 . 50
1 . fi 4
117
1 38
145
153
92
97
1 .35
1.49
1 .54
1 . 58
1 . 63
1 .6 8
1 08
1 28
134
141
149
157
62
79
8 :3
87
92
1 . 28
1 .4 3
1.47
1 .5 1
1.56
1.61
1 08
1 28
1 34
141
1 48
66
78
82
86
91
96
1 . 20
1 .3 5
1 . 40
1 .4 5
1 .50
1.55
107
127
1 33
141
148
1 56
1 . 26
1.40
1.44
1.48
1.53
1.57
95
1 14
1 20
1 26
1 33
140
55
66
70
74
78
82
1.18
1.32
1.37
1.41
1.46
1.51
96
113
1 20
1 26
133
140
59
70
74
77
82
86
1.10
1.25
1 . 29
1 . 34
1 . 39
1 .44
95
114
119
126
133
140
74
�
Underlined values, though beyo nd recommended
is in addition to normal loss of life.
% loss of life
'"Actual
Peak
Loa d
52
0.25
0.50
1 . 00
2 . 00
4.00
Nor mal
Ambient aC
20
10
0
88
102
77
90
94
1.33
1.51
1.57
1 26
148
156
81
94
98
1 . 24
1 . 43
1 . 49
1 24
1 48
155
85
98
102
1.13
1 . 34
1 22
147
75
1 . 20
1 . 37
1 .42
79
91
95
1 00
1.11
1 . 29
1 . 34
1 . 39
115
137
1 44
151
82
95
99
103
1 .0 0
1 . 20
1 . 26
1 14
1 36
143
1.47
116
138
1 44
152
70
82
86
90
95
100
1.11
1.27
1 .32
1 .38
1 .4 2
1 .48
107
126
133
141
147
156
74
85
89
94
98
1 03
1 .0 2
1.19
1 . 24
1 . 30
1.35
106
1 26
133
1 40
1 48
78
89
93
97
102
--
0.91
1.11
1.16
1 .2 2
105
126
132
1 40
81
93
97
101
63
74
77
81
85
90
1.01
1.17
1 .2 2
1 .27
1.32
1 . 37
95
1 14
1 20
1 26
133
140
67
78
81
85
89
94
0.91
1.08
1.13
1.19
1 . 24
1 . 30
95
113
119
126
133
140
71
82
85
89
93
97
0.80
0.99
1 . 05
1 . 10
1.16
1.22
95
113
120
126
132
139
75
86
89
93
97
101
88
limits ( see 5.2.2.4 ), are given to assist in interpolation of the maximum limit.
water temperature should be 5 aC lower than the ambient temperatures shown above (see 3 .5 ) , and m ust be above zero a C .
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
86
98
!N
0
c:::
......
tl
t<J
""J
0
..,
t"'
0
;..tl
......
Z
0
s::
......
Z
t<J
..,
;.t"'
0
....
t"'
�s::
t<J
..,
00
t<J
tl
"<l
�
t<J
..,
�
�
Table 5(8)
Capability Table for Normal and Moderate Sacrifice of Life
55 ° C Rise, Forced-Oil-Cooled (Non-Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transformers
Equivalent Load Before Peak Load 70% of Maximum Nameplate Rating
�00
=
Hours
of
Peak
Load
%
Loss
of
Life
Normal
!
2
0.25
0.50
1 . 00
2.00
4 . 00
Normal
1
0.25
0.50
1 . 00
2.00
4.00
Normal
m
f-'
2
4
0.25
0.50
1 . 00
2.00
4.00
Normal
0.25
0.50
1 . 00
2.00
4.00
Normal
8
24
Peak
Load
�Per
nit)
1 .99
2.21
0
10
HotSpot
Tsmp
H ot-
( C)
141
165
TopOil
Temp
(0C)
Peak
Load
(Per
Unit)
56
65
1.89
2.11
Ambient °c
20
Spot
Temp
TopOil
Temp
Peak
Load
(Per
HotSpot
T8mp
1 40
163
62
71
1.79
2.02
139
163
t C)
(0C)
Unit)
( C)
30
TopOil
Temp
Peak
Load
(Per
HotSpot
Temp
68
77
1.67
1 .9 2
138
163
t C)
Unit)
tC )
40
50
To rOi
Temp
(oC)
Peak
Load
(Per
Unit)
HotSpot
Temp
TopOil
Temp
(C)
Peak
Load
(Per
Unit)
Spot
Temp
Temp
74
83
1.54
1.81
136
162
80
89
1.35
1 . 69
129
160
84
95
(C)
Hot-
(C)
TopOil
(0 C )
"'l
0
�
is:
t'i
�
00
e:::
"C
�
0
f-'
0
0
is:
<:
»
::is
1.76
1 .95
1 34
1 58
65
77
1.67
1.87
1 33
1 58
70
82
1 .58
1.78
133
156
75
86
1 . 47
1 . 68
131
155
79
91
1 . 36
1 . 59
129
1 54
84
96
1.19
1.18
1 23
152
86
100
::3
::c
01
01
°
C1
0
�
1.57
1.73
127
150
69
83
1 .49
1 . 66
1.71
1 26
149
1 57
73
86
91
1 .40
1 . 58
1 . 63
125
148
1 56
77
90
94
1.31
1.50
1.55
1 24
148
155
81
94
98
1.20
1.41
1.47
122
146
1 54
84
97
1 02
1 . 05
1.31
116
144
86
101
m
01
°
C1
»
<:
t'i
�
1 . 44
1.58
1 . 63
1 . 6R
117
139
146
1 54
67
80
85
89
1.36
1.51
1.56
1.61
117
138
145
152
71
84
88
93
1.28
1 .44
1 .49
1.54
74
87
92
96
1.19
1 .36
1.41
1 .47
115
137
1 44
152
78
91
95
1 00
1 .09
1 . 28
1 . 33
1 . 39
113
136
143
1 51
81
94
98
1 03
1 . 50
1.55
1. 44
107
1 27
133
140
148
156
70
82
86
90
95
1 00
1.10
1.27
1.32
1.37
1.43
1.48
1 06
1 26
133
140
148
155
73
85
89
94
98
103
1 .0 1
1.19
1 . 24
1 . 29
1 . 35
105
1 26
133
139
147
1.10
1.25
1 .29
1 . 34
1 . 39
1.44
95
113
119
126
133
140
63
74
77
81
85
90
1 .0 1
1.17
1.21
1.27
1.32
1 . 37
95
113
1 19
1 26
133
1 40
67
78
81
85
89
94
0.91
1 . 08
1.13
1 .1 9
1 . 24
1 . 30
95
113
1 20
1 26
1 33
140
71
82
85
89
93
98
1 . 35
1 . 49
1 . 54
1 . 58
1 . 63
1.67
107
127
1 34
141
149
156
62
74
78
83
87
92
1 .28
1 .42
1 .4 7
1.51
1.56
1.61
107
127
1 33
141
1 48
1 56
66
78
82
86
91
96
1.19
1.35
1.40
Normal
0.25
0.50
1.00
2.00
4.00
1 . 26
1 .40
1 .44
1 . 48
1 . 53
1 . 57
95
114
120
1 26
1 33
140
55
66
70
74
78
1.18
1 . 33
1.37
1.41
1.46
1.51
95
114
1 19
1 26
133
140
59
70
73
77
82
86
0.95
1.19
1.25
83
98
�
»
Cl
t'i
::is
Ii
t:l
77
89
93
97
1 02
0.25
0. 5 0
1 . 00
2.00
·1 . 0 0
82
116
138
144
152
109
135
142
NOTE: Underlined values, though beyond recommended limits (see 5.2.2.4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
"Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5), and must be above zero °c.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
0.88
1.10
1.15
1.21
102
125
132
139
80
93
97
101
0.80
0.98
1 .04
1 .1 0
1.16
1.22
95
113
119
1 2 1)
133
140
75
R6
89
93
97
101
Ii
Cl
�
......
00
t'i
Q»
:-' Z
a;> 00
t-:> ......
� j::;;
a;> t'i
ao trl
f-' t'i
C"l >
O1 Z
:-" 00
co .....
"" ;:;
Table 5(t)
Capability Table for Nonnal and Moderate Sacrifice of Life
°
55 C Rise, Forced.()il·Cooled (Non.Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transfonners
Equivalent Load Before Peak Load 90% of Maximum Nameplate Rating
':'
gJ
g; t:EJ
....
=
10
0
Hours
of
Peak
Load
1.
2
1
�
t-:)
%
Loss
of
Life
�Per
nit)
Load
·
Hot
Spot
Temp
(o C)
Top·
Oil
Tsmp
( e)
Peak
Load
(Per
Unit)
Hot·
Spot
Tsmp
( e)
y
To Oi
Temp
tc)
30
Peak
Load
(Per
Unit)
Hot·
Spot
Tg mp
( e)
40
To r Oi
Temp
(o e )
·
Peak
Load
(Per
Unit)
Ho t
Spot
Temp
(oC)
50
Top·
Oil
Temp
(o e )
60
69
1.81
2.04
1 38
1 63
66
75
1.70
1 .9 4
137
161
72
81
1 .54
1.83
1 32
1 60
77
87
1 .03
1.71
103
158
73
92
Normal
1.71
1.91
133
1 57
67
79
1 .6 2
1.82
1 32
1 56
72
83
1.52
1.73
1 30
154
76
87
1 . 38
1 .6 3
1 26
1 53
79
92
0.97
1 . 52
99
151
73
96
0.25
0.50
1.00
2.00
4.00
0.25
0.50
1 .00
2.00
4 . 00
0.25
0 . 50
1 . 00
2.00
4 . 00
0.25
0.50
1 . 00
2 . 00
4 . 00
Normal
24
Peak
139
163
Normal
8
( e)
Top·
Oil
Temp
(oC)
1 .9 2
2. 1 4
0 . 25
0.50
1 . 00
2 . 00
4 . 00
Normal
4
{lnit)
Hot·
Spot
Tsmp
Normal
Normal
2
Peak
Load
er
Ambient °c
20
0.25
0.50
1 .00
2.00
4.00
1.55
1.71
1 .76
126
148
156
70
82
87
1 .4 6
1.63
1 . 69
124
147
1 55
73
86
91
1 . 36
1 . 55
1 . 61
122
147
154
76
90
94
1 . 24
1 . 46
1.52
119
145
152
79
93
98
0.93
1 . 36
1 . 43
97
143
151
72
96
101
1 .43
1 . 57
1 . 62
1 . 67
116
1 37
145
152
67
80
84
89
1 . 34
1 . 50
1.55
1.60
115
137
144
151
-
70
83
87
92
1 .26
1.42
1.48
1 .5 3
114
136
143
151
-
73
87
91
96
1.15
1 . 34
1.40
1.45
110
135
142
1 50
76
90
94
99
0.92
1 .2 5
1 .31
1.37
96
133
141
148
72
93
97
102
--
1 .35
1 .4 9
1 . 53
1 .58
1 .6 2
1 .6 7
107
1 27
134
140
148
156
62
74
82
87
92
1.27
1.42
1.46
1.51
1.56
1.61
106
1 27
1 33
1 40
1 48
1 55
65
78
81
86
91
95
1 . 18
1.34
1 . 39
1.44
1 .49
1 . 54
105
1 26
1 32
1 39
147
155
69
81
85
89
94
99
1 .08
1 . 26
1 .3 1
1 .37
1.42
1.47
103
125
132
139
147
1 54
72
85
89
93
98
0.91
1.18
1.23
1 .29
1 . 34
95
1 24
131
1 38
1 46
71
88
92
97
101
1.26
1 . 40
1.44
1.48
1 .53
1 . 57
95
1 14
1 20
126
133
140
55
66
70
73
78
82
1.18
1.32
1.36
1.41
1.46
1.51
95
114
119
1 26
133
1 40
59
70
73
77
82
86
1 . 09
1 . 24
1 . 29
1 . 34
1 . 39
1 . 44
95
113
120
1 26
132
140
62
73
77
81
85
90
1 . 00
1.17
1.21
1 . 26
1.31
1 . 37
94
113
119
126
132
140
66
78
81
85
89
93
0.90
1 . 08
1.13
1 .18
1 . 24
1 . 29
94
113
119
1 26
132
1 40
71
82
85
89
93
97
Peak
Load
(Per
Unit)
Hot·
Spot
T5mp
( C)
1 .54
152
96
1.36
1.48
144
156
98
104
Top·
Oil
Temp
tC )
t;j
t:EJ
t:EJ
0
c::
.....
1 . 23
1 .31
137
147
98
103
1.12
1.21
128
138
94
100
t:I
t:EJ
"2j
0
�
t"
0
>
t:I
Z
(.)
s::.
....
Z
78
1.Q£
1 . 05
1.13
1 . 20
1 20
1 29
1 38
90
95
1 00
0.99
1 . 04
1.10
1.16
1 .2 2
113
119
125
132
140
86
89
93
97
101
NOTE: Underlined values, though beyond recommended limits (see 5 .2.2.4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to nonnal loss of life.
'" Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5), and must be above zero ° e.
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
t:EJ
�
>
t;"
0
F
�
s::
tzJ
�
t:EJ
t:I
"1:1
0
�
t."l
�
>-3
�
>
z
00
"1j
0
�
Table 5(u)
Capability Table for Nonnal and Moderate Sacrifice of Life
55 °c Rise Forced-Oil-Cooled ( Non-Directed Flow - FOA, FOW*, and OA/FOA/FOA) Transfonners
Equivalent Load Before Peak Load 1 00% of Maximum Nameplate Rating
=
10
0
Hours
of
Peak
Load
%
Loss
of
Life
Normal
I
2
0.25
0.50
1 . 00
2.00
4.00
a
0 . 25
N or m l
1
m
0.50
1.00
2.00
4 . 00
Normal
w
2
0.25
0.50
1 . 00
2.00
4.00
Normal
4
0.25
0.50
1 . 00
2 . 00
4.00
Normal
8
0.25
0.50
1 . 00
2 . 00
4.00
Normal
24
0.25
0.50
1 . 00
2 . 00
4.00
Peak
Load
er
!lnit)
HotSpot
T�mp
( C)
TopOil
Temp
(0C)
Peak
Load
Per
Jnit)
HotSpot
Temp
(DC)
20
TopOil
T�mp
( C)
1.88
2.10
1 39
162
--
62
71
1.76
2.00
-
�
68
77
1 . 68
1 . 88
132
156
67
79
1 . 58
1.79
-
72
84
-
137
130
155
is:
Ambient °c
tz:J
30
To y Oi
T� mp
( C)
40
To y Oi
T!5 mp
( C)
Unit)
HotS pot
T�mp
( C)
1.61
1 . 89
1 33
lQQ.
73
83
1.06
1 . 77
99
157
68
88
1.44
1.70
125
154
75
88
1.03
1 .59
97
151
-
68
92
97
143
150
68
93
97
Peak
Load
(Per
-
Peak
Load
(P e r
Unit)
HotSpot
Temp
(DC)
Peak
Hot-
Load
(Per
Unit)
Spot
Temp
(DC)
1 . 59
151
�
00
50
To y Oi
Temp
( C)
92
Peak
Load
Hot-
Unit)
Spot
Temp
( C)
1.47
150
(Per
TopOil
Temp
ee)
98
e::
"d
>-3
0
.....
0
0
is:
<:
>
:::;:J
::3
1 .4 4
1 . 54
145
156
95
1 00
::.:
1.31
1.49
142
160
99
!Ql
01
01
°
0
0
�
IS>
74
89
94
1 .23
1.41
1.46
1.52
110
135
142
150
71
86
90
95
1.02
1.33
1.38
1.45
1 .50
96
133
140
149
158
67
89
93
99
1 04
155
65
77
81
86
90
95
1.16
1 . 34
1 . 38
1 .44
1.49
1 .54
103
1 25
1 :3 2
1 39
147
155
67
81
85
89
94
99
1.01
1.25
1 . 30
1.36
1.41
1.47
95
124
131
1 38
146
1 54
95
113
1 19
1 26
133
1 40
59
69
73
77
82
86
1 .09
1.24
1.29
1 . 34
1.39
1 .4 4
95
113
119
1 26
133
140
63
73
77
81
85
89
1.00
1.16
1.21
1 . 27
1.31
1.37
95
113
119
1 26
132
1 39
73
86
91
1.31
1 . 53
1. 5 9
1.33
1.50
1.54
1.59
114
1 36
143
151
69
83
87
92
61
74
78
82
87
92
1.26
1.41
1.46
1.51
1.55
1.61
1 05
126
132
140
147
54
66
69
73
77
82
1.18
1.32
1.37
1.41
1.46
1.51
69
82
87
1.44
1.61
1.67
1.42
1.57
1.61
1.66
115
137
144
152
66
80
84
89
1.34
1.49
1.53
1.58
1.62
1.67
106
1 27
133
140
1 48
1 56
1.26
1.39
1.44
1.48
1.53
1.58
95
113
119
126
132
140
-
118
145
153
123
146
154
124
147
155
1.53
1 .69
1.74
1 .0 3
1 .44
1.50
-
-
1 . 30
1 . 39
1.47
136
147
158
93
99
1 05
1.22
1. 34
137
151
98
106
1.21
1 .29
1.35
1 28
1 38
147
90
96
101
1.14
1 .25
130
143
95
103
67
84
88
92
97
1 .1 4
1 .21
1.27
1 . 34
120
1 29
137
145
86
91
96
101
1 . 09
1.17
1.25
124
1 34
144
92
98
104
67
77
81
85
89
93
1 . 08
1 .13
1.18
1.23
1 . 29
113
118
125
132
1 39
82
85
89
93
97
1 . 04
1 . 09
1 . 16
1.21
119
1 25
132
1 39
89
93
97
101
�
NOTE: Underlined values, though beyond recommended limits (see 5 . 2 . 2 . 4 ), are given to assist in interpolation of the maximum limit.
% loss of life is in addition to normal loss of life.
• Actual water temperature should be 5 °c lower than the ambient temperatures shown above (see 3.5), and must be above zero D C .
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
""
°
0
>
<:
tz:J
�
>
C)
tz:J
-:::;:JZ
0
-Z
C)
�
Ul
trl
0
01 >
:-> z
"" --
co 00
.
....
�
co trl
oo trl
.... trl
ANSI/IEEE
C57.92-1981
IEEE GUIDE FOR LOADING MINERAL-OIL-IMMERSED POWER
line so determined and the vertical line through
the intersection of line for the desired time
(2 h ) and time constant ( 3 . 5 h), determine the
top-oil temperature rise ( 54 ° e) at the end of
the short-time period (2 h).
6. Calculation of Temperature and Loss of
Life for Short-Time Loads above
Transformer Rating
The calculations shown in this section are for
65 ° C rise transformers. These methods can be
used for 5 5 ° C rise transformers.
6.3 Hottest-Spot Conductor Rise to Top Oil
Gradient. On Fig 9(a), start at percent load
( 1 67%) on the horizontal scale and go up the
curve for full-load hottest-spot conductor rise
(30 o e). Go to the left and read hottest-spot
conductor rise over top oil (68 ° C) for the
short-time load.
-
6.1 General. Short-time loads above the rating
which use up different amounts of insulation
life for transformers having the characteristics
shown in Table 2 are given in Tables 3 (a)-3(u).
Transformers which have other characteristics
will have different load capabilities than those
indicated in this guide. Section 6 gives informa­
tion from which similar values can be derived
for those transformers.
Where a graphical solution is desired, use may
be made of Figs 6-9. As an example of the use
of these figures, consider an OA transformer
with a short-time load of 167% for 2 h follow­
ing a 33% load. Assumed transformer char­
acteristics at nameplate rating are :
Ratio of losses (R)
3.2
Top-oil rise over ambient
temperature at rated load
50 ° C
Time constant
3.5 h
Hottest-spot conductor
rise over oil
30 ° C
n (oil exponent)
0.8
m (winding exponent)
0.8
6.4 Hottest-Spot Conductor Temperature. Ob­
tain the hottest-spot conductor temperature
by adding ambient temperature (30 ° e) , top-oil
rise ( 54 ° C) and hottest-spot rise over top oil
(68 ° e ) giving 1 5 2 ° C .
6.5 Percent Loss o f Life. From Fig 3, obtain
the loss of life (0.19%) for the hottest-spot
temperature ( 1 52 °e) and the duration of the
load (2 h). In using this simplified procedure, it
is assumed that the hottest-spot temperature is
constant at its final value throughout the peak
load period. When this assumption is made, the
loss of life during the cooling period and during
the period prior to the peak load can be
ignored . This is only a convenient and sim­
plified procedure for approximating the loss o f
life for short-time loading conditions. A more
mathematically precise procedure was used in
preparing the values in Tables 3(a)-3(u) and
5(a)-5(u), wherein a computer program used
the 24 h hottest-spot conductor temperature
profile developed from various two-step load
cycles, the transformer characteristics and am­
bient temperatures shown in these tables.
6.2 Top-oil Rise Determination
( 1 ) On Fig 6(a), start at initial percent rating
( 33%) and move horizontally to the ratio of
losses curve (R
3. 2). Go down to the line for
full-load oil rise ( 50 ° C). Move horizontally to
read initial oil rise ( 2 1 ° C).
( 2 ) Determine the ultimate top-oil temper­
ature rise for the short-time load ( 167%). On
Fig 8(a), locate 167% on right side o f the graph
and m ove horizontally across to the ratio of
losses curve (R
3. 2). Move down to the
fUll-load oil-rise curve (50 ° C). Move horizon­
tally and read the ultimate oil rise (99 ° C) at
left of graph.
(3) On Fig 7(a) , set a straight edge at the
initial oil-temperature rise on the left scale
(21 ° C) and at the ultimate top-oil rise on the
right scale (99 ° C). At the intersection o f the
6.6 Method of C onverting Actual to Equivalent
Load Cycle
6.6.1 Permissible loading as obtained from
Tables 3(a)-3(u) and 5 (a)-5(u) is a function
of the initial load and the peak load and their
durations. Each loading combination in the
tables is the result of a simple two-step load
cycle consisting of a constant initial load of
50%, 70%, 90% or 1 00% of rating followed by
a rectangular peak of the magnitude and
duration given in the table. The assumed
loading for the calculations in the tables is
illustrated by Fig 10.
6.6.2 Ordinarily the daily load cycle is not so
simple but is like the cycle represented by the
solid line in Fig 1 1 consisting of load fluctua-
=
=
64
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
TRANSFORMERS UP TO 100 MVA WITH 55 ° C OR 65 °c AVERAGE WINDING RISE
200
140
120
'BO
1--+-+-I--I-+�-+- +----j-+--T':.6.:l�-t--1
I---+--+--I---- +i-+--+- -+--+---+--,.ti,j�-I
!
100
- --t
�2
160
1 10
1-- --+--+--+_+_
1-
90
....
z
..
4
V
-�6
8
"'
....
V
70
1---+--+--- '¥I'-¥--+t-- +-+--o
60
40
f--+ ---t----I'--t-i;
30
����-L-LL-�-L�L-�_�-L�
O ��
100 1 1 0
90
80
70
o
10
20
30
40
60
50
/
-
1
o
V
120
1 10
90
- - .,.l-- I
,
,
54·
!
I
,
,
!
I
, 1 'i<4&/'
" ��
.....
_ f:J� 0(,
v�
' -�� ���;>--�
I
.
50
40
a
WI
�
�
I
60
'a
r- -
/':
V"�
��JP
I
70
t;cj . 1\,
-f- ';
.,
o
30
I
��
10
f- .5'
...e%
���__f-"
f:::
::=
� Fi
100 1 1 0
90
80
70
60
50
40
PERCENT OF FULL-LOAD OIL RISE
n = 1.0
180 f--
2
f- f-
•
1 60
140
1 20
100
Z
"
o
IH
/
u
"'
'" B
t- ....
f-
1 20
I
130
140
V
/
Rj
;!
8
f- �
0
'a
V
/
I
BO
o
..
o
�
6
g
V
-
g � � g
0
0
6 6 -
( -t)
l -e T
V
V ,./f-',..,.,..,.V
/'
V
k.-"
�
/
I
/'
5V V 8
V/V
' '''-
V/
V
V
Vj
i
I
o
�
6
I
,
f5 f2 � � g
0
16 2
/
-
I
2
/I
j
/
+
20
'2
o
,/
'V
I
i
40
/
V
//
i
I
60
a
;::::
f-I- .-f.I--'
"/I--':
.,-
i
<:>
_ �\J"
��
20
VV
--
-- -
2
'V
200
�
� -T !
AfJ;11"/
I
$/ V
�V L�:::-/.W( ,j
I.���..�-=
�
BO f---
20
!
--
- - --
100
30
-
!
/
.,-i-":
VV
V
(a )
r--f--
/
1
1
1
(a)
130
y
/
t
VALUE OF T IN
140
/"
....f.-
I
2
6
o
/"
V Vvr.
-
o
PERCENT OF FULL-LOAD OIL RISE
./
,..,.-
5 /V
4
y,-
VlJ
-
./"
1
1
---
.-
7!"
i'
40
20
V
2
j
80
50
.7
r- '-
10
100 -
- --
1 Hy'
120 - ,! 8
I---+- -+--f- -+
80
140
-
V
0
0 0
-
"
N
g iil 8 888
N
N
rt'l 'Ct1n
t
VALUE OF T IN
(b)
(b)
Fig 6
Initial Oil Rise
Fig 7
Top-Oil Temperature at End of Specified Load �eriod
65
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57 .92·1981
IEEE GUIDE FOR LOADING MINERAL·OIL·IMMERSED POWER
180 ,..--..--..-----.--..,.---.---......
�
�
�--+---�---+---4----r-�
= 140
1--+---+----1I--+-I-�
z
o
Q.
1 20
�
100 1--+---+---11--
lLI
(f)
a:
I­
o
Q.
�
I­
o
:r
1---+--+--1--"
�
140
1--+--�-_+--+_��
�
120
1--+---+---t--hH-l
:::
'"
� 100
w
Ul
80 1--+--+--+
40
120
80
160
200
PERCENT RATED kVA
80
1---+---+-----1
�
'"
60
I---+---+_-
�
40
1---+--+��f7��-�
Q.
'"
w
...
...
40 1--+--�����4
1--+---+---t-
it
b
-+-�"4-�.f-:If-��"""7I
c:' 60 �-+-
I­
(f)
160
�
..J
1--+---+----11---1
�
a:
lLI
180 r--'----,---,r---,
o ���--�--�
240
40
120
80
160
200
PERCENT RATED kVA
m = 0.8
m =
1 .0
(b)
(a)
Fig 9
Hottest-Spot Conductor To
Top-Oil Gradient
I�O
137%
PEAK LOA D
TRANSFORMER RATING
2 HOURS
�%
INITIAL LOAD
O L-____L-____�_____�____�
12
6PM
12M
6AM
12
ASSUMED LOAD CYCLE
Fig 1 0
Assumed Load Cycle
66
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57.92-1 981
°
°
TRANSFORMERS UP TO 1 00 MVA WITH 5 5 C OR 65 C AVERAGE WINDING RISE
I�
o
L-________�________�__________�________�
12
6 AM
6PM
12M
12
ACTUAL LOAD CYCLE
Fig 1 1
Actual Load Cycle
tions throughout the day. There is usually one
period in the daily load cycle when the load
builds up to a considerably greater value than
any reached at other times. Generally, the
maximum value or peak load is not reached
and passed suddenly, but builds up and falls off
gradually.
6.6.3 To use the loading recommendations,
the actual fluctuating load cycle should be
converted to a thermally equivalent two·step
load cycle such as is represented by the dashed
line in Fig 1 1 . A transformer supplying a
fluctuating load generates a fluctuating loss,
the effect of which is about the same as that of
an intermediate load held constant for the
same period of time. This is due to the heat
storage characteristics of the materials in the
transformer. A constant load which generates
losses at the same rate as the average rate
caused by the fluctuating load is an equivalent
load from a temperature standpoint. Equiva·
lent load for any part of a daily·load cycle may
be expressed by Eq 2.
Equivalent load or rms value
) L 1 2 t l + L2 2 t
respective durations of
these loads
6.6.4 Equivalent initial load is the rms load
obtained by Eq 2 over a chosen period pre­
ceding the peak load. Experience with this
method indicates that quite satisfactory results
are obtained by considering only the 12 h
period preceding the peak in determining the
equivalent initial load. Time intervals ( t ) of 1 h
are suggested as a further simplification of the
equation which, for a 1 2 h period, becomes
Eq 3.
Equivalent initial load
0.29
.
.
etc
=
L2 2
+
L3 2 + . . . LI
2
2
( Eq 3 )
=
average load by inspection
for each 1 h interval of
the 12 h period preced­
ing peak load
6.6.5 Equivalent peak load of a load cycle is
the rms load obtained using Eq 2 for the
limited period over which the major part of the
actual irregular peak seems to exist. The
estimated duration of the peak has consider­
able influence over the rms peak value. If the
duration is overestimated, that is, if the time
period to which Eq 2 is applied is too long, the
rms peak value may be considerably below the
maximum peak demand. To guard against
( Eq 2 )
where :
LI , L , L3,
2
+
L1 , L , . . . L12
2
=
. tn
LI 2
where :
+ L3 2 t3 + . . . Ln 2 tn
2
tl + t2 + t3 +
J
=
various load steps in %, per
unit, or in actual kV A or
current
67
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
C57 .92-1 981
IEEE GUIDE FOR LOADING MINERAL-OIL-IMMERSED POWER
T()
overheating due to brief, high loads during the
thermal time constant of transformer
for any load L and for any specific
peak period, the rms value for the peak load
period should not be less than 90% of the
tem perature
6.6.6 The above method may be used to
an
convert
To
Th s
continuous part is 7 0% and the peak 1 4 0% of
rated load. Table 3(b) shows that in a 30 D C
=
C (8 u
-
8 i ) /P
hottest-spot time constant
P
ambient temperature the permissible 1 h load
change in total loss in watts due to
change in load
70% load is 1 7 2%, therefore, the
transformer
between
initial top-oil rise, or
irregular load cycle as shown in
Fig 11 to a two-step load cycle . In this case the
following
differential
the ultimate top-oil rise and the
integrated h alf-hour maximum demand.
can carry this load cycle daily
time
Tr
without sacrifice of normal life expectancy.
constant
of
transformer
temperature rise of zero D C
6.7 Equations for Calculating Transient Heat­
ing of Oil-Immersed Transformers
6.7 . 1 General. The loading tables in this
P{l
total loss in watts at rated load
C
thermal
guide are based on average characteristics of a
capacity
of
transformer
(Wh t c )
wide range of transformer ratings. Tables 2 and
4 give the characteristics used in calculating the
6 .7.3 Temperature De termination Equations
loadings in the Tables 3(a)-3 (u) and 5(a)-
5(u). When the characteristics of a particular
Hottest-spot temperature :
transformer vary appreciably from those in the
(Eq 4 )
tables or when more accurate loading capa­
bilities are desired, the basic equation s in this
section may be used.
List
6.7.2
Transient heating equation for top-oil rise over
ambient temperature :
of Symbols. Unless otherwise
expressed, all temperatures are in D C and all
80
times are in hours.
8a
ambient temperature
8g
8g (fl)
8 hs
=
(8u
-
8d
+ 8i
(1 - e ;t�
( Eq 5 )
Ultimate top-oil rise for load L :
hottest-spot conductor rise over top-
8u
oil tern perature
=
=
8
hottest-spot conductor rise over top­
oil temperature at rated load
f(K2 R + 1
L (R + 1 )
{l
l]
n
( Eq 6 )
Ultimate hottest-spot conductor rise over top­
oil for load L :
hottest-spot winding temperature
( Eq 7 )
top-oil rise over ambient temperature
8g (fl)
top-oil rise over ambient temperature
at rated load
initial top-oil rise for t
K
L
=
under
consideration,
rise over top oil6
any
n
units
R
ratio of load loss at rated load to
e
2 . 7 1 8 2 8 (base of natural logarithm)
t
duration of load in hours
1 5 °C7
( Eq 8 )
FOA,
FOW,
OA/FAj
1.0 for directed flow FOA, FOW
=
n
+
FOA, OA/FOA/FOA
m
in
average conductor
non-directed
L
ratio of load L to rated load
load
=
0.8 for OA, OA/ F A, OA/F A / FA and
m
0
ultimate top-oil rise for load
for
rated load beginning with initial
0.8 for OA
0.9 for OA/F A, OA/F A/F A
6
At rated
kV A from manufacturer's test.
Hottest.spot conductor rise over averagl' con­
°
°
ductor rise is assumed to be 1 5 C for 65 c rise
°
°
transformer, 1 0 C for 55 c rise transformers. (Values
are usually lower than the 15 ° C and 10 0 C, but may be
higher for a few designs).
7
no-load loss
68
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
TRANSFORMERS UP TO 100 MVA WITH
n
=
n
=
m
55 ° C OR 6 5 °c AVERAGE WINDING RISE
ature rise and ultimate temperature rise. If n is
not unity , the percentage varies and is a func­
tion of both i nitial temperature rise and
ultimate temperature rise . In particular, if n
equals 0 . 8 , the percentage of 67 if the initial
temperature rise is zero .
If the initial temperature rise is greater than
zero, the percentage is lower than 67 and
decreases as the initial temperature rise ap­
proaches a given ultimate temperature rise. If
the initial temperature is approximately equal
to the final temperature, whether just above or
just below it, the percentage is approximately
63. If the initial temperature is greater than the
ultim ate temperature, the percentage is less
than 6 3 .
Since evaluation of the exact percentage for
cases where n is not unity and where the initial
temperature rise is not zero becomes very
laborious, it is frequently advisable to use the
approximate value of 63%. In the more fre­
quently encountered cases where n is approxi­
mately 0.8, the error resulting from this
procedure is not large compared to the ex­
pected error in input data.
If n
1.0, Eq 9 is correct for any load and
any starting temperature . If n or m is less than
1 .0 , Eq 9 holds only for full-rating starting
cold . If n is less than 1 , the time constant for
any load and for any starting temperature for
either a heating cycle or cooling cycle is given
in Eqs 10 and 1 1 .
1.0 for FOA, FOW, OA/F A/FDA, OAf
FOA/FOA
the exponential power of total loss
versus top-oil temperature rise
the exponential power of winding loss
versus winding temperature rise
Time constant at rated kVA :
_
Tr -
C8 n
p
n
( Eq 9)
For non-directed flow transformers :
C
=
ANSI/IEEE
C57.92-1981
0.06 (weight of core and coil assembly
in pounds) + 0 . 04 ( weight of tank
and fittings in pounds) + 1.33 (gal­
lons of oil)
For directed flow transformers :
C
0 .06 (weight of core and coil assembly in
pounds) + 0 .0 6 (weight of tank and fittings in
pounds) + 1.93 (gallons of oil)
6.7.4 Equation Corrections. Theoretically,
several corrections should be made when using
the foregoing equations in calculating transient
oil rises, such as corrections for change in :
( 1 ) Time constant for load above rating
( 2 ) Ultimate conductor loss at end of load
period
( 3 ) Oil viscosity
In making general calculations based on
assumptions of transformer characteristics and
maximum hottest-spot conductor temperatures
which generally have a large factor of safety,
results close enough for all practical purposes
are obtained if all of these corrections are
omitted, and the simpler formulas are used.
Using these corrections implies greater ac­
curacy than is present in the basic data,
therefore the load values shown in Tables
3(a)-3(u) and 5(a)-5(u) were calculated using
the equations without corrections.
6.7.5 Time Constant. The time constant is
the length of time which would be required for
the temperature of the oil to change from
initial value to the ultimate value if the initial
rate of change were continued until the ulti­
mate temperature was reached.
If n (the exponential power of total loss
versus top-oil temperature rise ) equals unity ,
63% of the temperature change occurs in a
length of time equal to the time constant
regardless of the relationship of initial temper=
=
( Eq 10)
If
starting cold, as 8 ;
=
(1 _ ! )
n
0, Eq 10 reduces to :
( Eq 1 1 )
6.7.6 Winding Loss ( Load Loss ) . As the
resistance of the winding for ultimate condi­
tions is greater when the temperature is greater
for loads above rating than it is for rated load
conditions, a resistance correction factor may
be applied to Eqs 6 and 7 . The correction
factor is a multiplier to be applied to the K2 in
each equation to reflect the change in winding
loss due to the increase in winding resistance.
69
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
ANSI/IEEE
IEEE GUIDE FOR LOADING MINERAL·OIL-IMMERSED POWER
C57.92-1981
The values of the exponents, m and n, used in
top-oil rise, hottest-spot rise, and time con­
ance corrections are applied . The manufacturer
constants
stant, all at rated load), (2) the aging curve
the equation may not be correct when resist­
should be consulted when such corrections are
for
the
insulation
system
(from
Fig 1 ) , ( 3) ambient temperatures, ( 4 ) initial
to be included.
continuous load, ( 5 ) peak load durations and
the specified daily percent loss of life.
6.7.7 Viscosity of Oil. The ultimate temper­
The loss of life indicated in the tables is
ature rise of oil for a constant heat input
decreases slightly as the temperature of the oil
based on a 24 h load cycle. For 65 °c units it is
increases. This is due to a decrease in the
the loss in excess of the 0.0369% per day
to offset the effect of increased resistance.
For 55 ° C units it is the loss in excess of the
viscosity of the oil. The viscosity change tends
produced by continuous operation at 1 1 0 ° c.
0. 0369%
per day
operation at 95 ° C.
produced
by
continuous
A systematic convergence process is used to
7. Method Used for Computer Calculation
obtain the highest
of Loading Capability Tables
allowable
peak load. An
initial trial is made with an assumed peak load
midway between the minimum (continuous)
The methods and calculations described in
load and the maximum permitted peak load
6.6.3 through 6 . 7 . 5 were used in developing a
(200%). Using this peak load, aging calculations
computer program designed to provide more
are made at varying time intervals (depending
5(a)-5(u) than would be possible using the
the 24 h, to determine the total daily insula­
accurate
values
for
Tables
3(a)-3(u)
and
on the time duration of the peak load) during
hand method covered in 6 . 2 - 6 . 5 of this
tion
guide. See ANSI/IEEE C57.91- 1 9 81 [ 4 ] for a
aging,
imposed
by
the
load
cycle.
A
comparison is made between the calculated and
more complete explanation of the computer
the specified percent loss of life.
program .
Depending on the results the peak value is
changed and the calculation repeated until the
The program computes and prints the max­
calculated value of total percent loss of life is
power transformer and meet specified loss of
the peak load and corresponding values of peak
within ±4% of the desired value. At this point
imum peak load that can be impressed on a
life limitations within a ±4% tolerance .
hottest-spot temperature, peak top-oil temper­
ing: ( 1 ) transformer characteristics (loss ratio,
specified percent loss of life are printed out.
Input to the program consists of the follow­
ature,
total
percent
loss
of
life,
and
the
70
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.
Appendix
(Th is Appendix is not a p art of ANSI/IEEE C 5 7 .92-1 981 , IEEE Gu ide for Loading Mineral-O il-Immersed Power
Transformers Up To and Including 1 00 mVA with 5 5 ° C or 65 ° c Average Wind ing Rise . )
Unusual Temperature and Altitude Conditions
Table Al
Maximwn Allowable Average Temperature. of Cooling Air for Carrying Rated kVA
3000 �
(9900 Feet)
4 000 Meters
( 13 200 Feet)
Method of Cooling Apparatus
1 000 Meters
(3300 Feet )
2 000 Meters
(6600 Feet)
Liquid -Immersed Self-Cooled
30
28
25
23
Liqui d-Immersed Forced-Air-Cooled
30
26
23
20
Liquid-Immersed Forced-Oil-Cooled
with O il-to -Air Cooler
30
26
23
20
Degrees C
* It is recommended that the average temperature o f the cooling a ir be calculated by averaging 24 consecutive
hourly read ings. When the outdoor air is the cooling me dium, the average of the maximum and minimum daily
temperatures may be used. The value o btained in this manner is usually sl ightly h igher, b y not more th an 0 . 3 °C,
than the true daily average.
At . Unusual Temperatures and Altitude
NOTES: ( 1) See ANSI/IEEE C57.1 2.00- 1 98 0, 4 . 3 . 2
for transformer insul ation capability at altitudes a bove
3300 ft ( 1 000 m).
( 2 ) Operation in low ambient temperature with the
top liquid at a temperature lower th an -20 ° C may
reduce dielectric strength between internal energized
components below design levels.
Service Conditions
Transformers may be applied at higher ambi­
ent temperatures or at higher altitudes than
specified in ANSI C57.12 .00-1980, but perfor­
mance may be affected and special considera­
tion should be given to these applications.
A4. Operation at Less than Rated kVA
Transformers may be operated at altitudes
greater than 3300 ft ( 1 000 m) without exceed­
ing temperature limits, provided the load to be
carried is reduced below rating by the percen­
tages given in Table A2 for each 330 ft ( 1 00 m )
that the altitude i s above 3300 ft (1000 m ) .
A2. Effect of Altitude on Temperature Rise
The effect of the decreased air density due to
high altitude is to increase the temperature rise
of transformers since they are dependent upon
air for the dissipation of heat losses.
Table A2
Rated kVA Correction Factors for Altitudes
Greater than 3300 ft (1000 m )
A3. Operation at Rated kVA
Types
af
Cool ing
Derating Factor
(% )
Liquid-immersed air-cooled
0.4
Transformers may be operated at rated kVA
at altitudes greater than 3300 ft ( 1000 m) with­
Liquid-immersed water-cooled
0.0
Liqu id-immersed forced-air-cooled
0.5
out exceeding temperature limits, provided
the average temperature of the cooling air does
Liquid·immersed forced -l iquid-cooled
with l iquid·to-a ir cooler
0.5
not exceed the values of Table Al for the re­
spective altitudes.
Liquid-immersed forced -liquid -cooled
with I iqu id·to-water cooler
0.0
71
Authorized licensed use limited to: UNIVERSITY OF CONNECTICUT. Downloaded on June 26,2014 at 21:59:20 UTC from IEEE Xplore. Restrictions apply.