AN ADVANCED PLANNING STUDY
FOR A RURAL ELECTRIC UTILITY
JOHN FRANKLIN ENGLE
A THESIS
submitted to
OREGON STATE COLLEGE
in partial fulfillment of
the requirements for the
degree of
ELECTRICAL ENGINEERING
June
193
APPROVED:
?rtes8or or
Deartment
lectrical ¿ngineering;
In Charge of Major
Chairman of School Graduate Committee
De an
Graduate School
Dabe thesis la presented
Typed by Elizabeth Heath
May 23, 1958
OF CONTENTS
TABI
IntroduetorySummary............
Dscr1ption of the Utility System.
Data Souxees
.
.
.
.
Initiai Design Point
.
.
.
.
.
.
.
.
.
Load and Population Growth Estimates
Advanced LoadStudy
.
.
.
.
.
.
.
.
.
.
.
.
.
Utilization of the Advanced Load Study
Concluelons.
.
.
Biblioxapby.....
Appendix.
,.
.
.
.
s
s
s
e
.
.
.
.
s
s
.
.
i
.
.
.
2
e
e
s
e
3
.
.
.
.
.
S
.
.
.
.
s
U
.
e
e
13
.
.
.
e
e
19
.
.
.
SÖC
*
.
.
.
s
.
..
.
.
.
.
19
.,
22
e
23
AN ADVANCED PLANNING STUDY FOR A RURAL
Introductory
An
iiLICTRIC UTILITY
Suimnary
advanced planning study provides a progrrn by which
utility
economically expand its operating facilities
to provide acceptable service to its presrxt customers
while allowing sufficient means to accommodate new ones.
a
may
Such a study must
utilIze the past operatin history of
t]
service area along with the present service
facilities and costs to form an extrapolation of the sercompany and the
vice requirements for the futuro operation of the utilit7.
The past history of the utility is used to formulate
curve of the system or consumer average load as a funetion of time, usually in years, This curve can be extraa
polated for
short period of future time to provide a
fairly reliable estimate of the load requirements. ThÍ
extrapolation presumes a regular growth with no unusually
large or abrupt changes in service demands. Because of
the nature of the service area of a rural electric utility,
the above extrapolation can be used only as a guido for
future planning. The load centers are usually indeter-.
a
requirements depending upon the
natural resourosa of each conunity. The overall load of
each community must be broken down into types of loads
minate, with the load
such that their requirements can be estimated according
to the p&rticular area,
In order to use the extrapolated curve ai a guide, lt
18 necessary to correlate the calculation methods with. tho
present utility system operation.
ja established,
When this correlation
the estimated future overall load can then
be distributed over the entire service area according to
tkze
characteristics st each coìîmunity.
An integrated eer'
ioe pian is then etablished such that each eoinmunit
line will have acceptable
the utility.
or
service with a minimum cost te
This involves the investigation of several
plans, each consldeed separately and together with the
other service areas to arrive ab a final design that will
provide the prescribed service requirements over a long
period of time.
Description of the Utility System
The rural electric utility for which this advanced
plan ning study was made had, In 1955, eleven substations
or delivery points to
te mr al
distribution system,
ßnergy was purchased by the utility at nino of the sub*
stations, with the utility transmitting energy to the
remaining two.
During
l9,
the utility served a maximum
of 5,016 consumers over 1,415 miles of distribution
and 33 miles of 69 kv transmission line,
Une
Each of the substations distributes power on a radial
feeder basis only, with interconnection between substations
possible through the distribution system.
The interconnoc-
tion between substations is not used in normal service
operation.
This system is shown an the key map, Figure 1.
Data Sources
The data for this study was taken from the cenbral
office records of Consumers Power, Inc., Corvallis, Oregon,
in the form of ìeter reading records, system maps,
con-
struotion specifications, transformer records, and cost
records for construction and operation.
The meter reading records
3vo the kilowatt-hour
energy consumption per month for each consumer and substation,
plus the maximum power demand for each subs bation
and a few consumers,
The consumer concentration, trans-
former size and numbers, and dìstrbution line length were
obtained from the system maps.
The construction specifi-
cations provided the necessary informatiofl to calculate
the impedance of the lines.
A book of demand tables prepared by the sural Elec-
trification Administration (2) was used to convert the
kilowatt.-hour energy data bo a power demand basis for sys-
tom load calculations.
La these tables were prepared using
data taken from utilities in the midwestern states,
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MILES
certain correction factors had to be applied to them, as
discussed later in this thesis.
These tables of power
demand applied to the domestic type of consumer only.
The curve of Figure 2 illustrates the past operation
of this system in terms of the average monthly load for
domestic consumers as a function of the years of service.
An equation for this curve over th
limits of the avail-
able data is given below.
7,8
P
+ 20
kwh/mo./consumer
(1)
Average monthly energy use for
domestic consumers
where P
Y
Number of yeais of service after
191.0
Using equation (i) as an indication of the average
domestic load growth, an estimated load for any future
year can be obtained.
The value of the future load
obtained by this method becomes less reliable as the
future period extends farther from the last data point
on the curve.
Fic, ire
'
2
represents a segment of a general saturad.
tion curve as illustrated
n Figure 3,
(1)
AVERAGE
POWER
DOMESTIC
FOR
V
"J
DD
WJ
rrr
kA(\JT1
EACR
FOR
z
o
CONSUMPTION
CONSUMERS
YEAR
g
P
D
8
Y
:
AVERAGE KWH. PER MONTH PER
NUMBER OF YEARS AFTER l94O
z0
t
7
z
tJ
CONSUMER.
6
-------
__
P
.
7.8y
.568
+20
I
-------;---
P: 549Y
-
It-
----
4
zwz
'2
4
o
2
i
TIME
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-
KEY
:;
SYSTEM
DATA.
___EXTRAPOLATION
LAST
2i
YEARS
AFTER
Fttgure
2
I94C
1L
OF
EQUATION.
EXTRAPOLATION
:
262
OF
POINTS.
1L
2
o
-J
w
IfJ)
>C!)
TiME
Figure 3.
General Saturation Curve
In comparing the two figures, Figure 2 is in the lower
portion of the general saturation curve, Figure 3, as the
load curve, Figure
2,
still has an increasing positive
slope at the last data pointe
An extrapolation of the data was made mathematically
by equation (1), as indicated in Figure
2
An approximate
check on the correlation between figures 2 and
3
was made
by a straiht line extrapolation of these load data.
The elope of equation (i) was evaluated at year l914O+l1,
with this slope then applied to
straight line equation
a
paesing through the last data point.
The straiht line
equation is given bolow
P
Í4.9
I
(2)
- 262 kwh/rno./consumer
The extrapolations shown on
Figue
2
indicate that the
last data point is below and near the inflection point o
the general saturation curve, Figure 3.
The straight line
extrapolation would probably cross the general saturation
curve within a short distance on the time axis to the
right of the last data point.
initial Design l'oint
The design kilowatt-hours for the entire system was
based upon the actual energy consumption for the month of
December,
l9SJ..
This month was chosen as a base because
it represented the winter peak load On the majorit7 ot
substations in the $7$ten.
AleO during this month, the
irrigation load was zero and ali concentrated loads were
operating at their normal demand.
The space heating load
was quite high, and thus would show up in the energy readings
The entire distribution system was divïded into see-
tione of approximately one to five miles in length.
This
section length was determined by the consumer concentra-
1enth
tion, phasing, wire size changes, and
ers.
The averace energy consumption wa
of tap feed-
determined for
each section for the domestic consumer load, while the concentrated loads, industrIal, were recorded by installed
tran8former capacity, energy consumption,
Ing if such were metered.
UsinL
the
&rid
demand read-
averae domestic con-
sumer load per section and the REA demand tables, a peak
kilowatt demand was obtained for each section,
The total
peak load was then computed for each substation service
area by adding all oÍ the peak deniands
The demand tables
included an unknown diversity factor in their conversion
from energy to demand.
A diversity factor of i.L
was assumed for the concentrated loads.
to 1.6
This factor was
based upoì the types of concentrated load, the type of
operation of each load, and the metered demand.
Most of
the small commercial class loads did not have demand metering,
o the
factor of seventy per cent of the installed.
transformer kva rating was used.
The seventy per cent
factor accounted for both diversity and loading.
This
factor was compared with those small loads that had demand
metering and was round to give reasonable agreement
The calculated peak subst*ttax
demand, as found above,
was then compared with the substation demand records for
the same peiiod.
t
was round that in most oases, the
calculated demand was higher than the metered demand.
the error between the metered and
If
*a1c1&ted demands was
greater than five per cent, the ca.cuIations and diversity
factor assumptions were rechecked,
recorded foD the winter peak load
As these data were
p criad,
the concentrated
loads were easily isolated and their diversity factors
checked accordjn
to the type of plant operation.
The
diversity factor for the domestic consumers was then
chaned until
the calculated substation peak demand was
within the five per cent high range of the metered demands.
An assumption was made that ali domestic consumers in
a given substation area would have the same diversity due
to similar geographic and economic conditions.
No dis-
crimination was made for space heating loads as compared
to normal domestic use.
The energy thus used was cal-
eulated into the average kilowstt-hours per consumer for
each line section, and the demand for that line section
determined accordingly.
The short past history of the
utility wIth respect to space heating indicated that an
increase in this load was usually localized In an area
where space heating already existed,
sideration,
Thus for future con-
the space heating load would be accounted for
u
by the percentage increase In energy consuizption for each.
line sectIori
The diversity factors obtained by the above outlined
method were checked several times by using them to calculate the substation peak demand on various substations in
the system for other winter months.
calculated demands were within
s.
In all cases, the
ten per cent high rango
of the metered dernands
As a result
of'
the above calculations,
kilowatt-hour consumption per
an average
onth por domestic consumer
was established for each substation area.
This fi,ure was
called the design kilowatt-hour figure for each substation
for the "present" load conditIons
diversity factors and
The above calculated
desin kilowatt-hours were assumed
to be a reliable base from which calculations for future
loadIn, could be made.
Load and Population Growth Estimates
The load estimates for future operating periods were
based upon the mathematical extrapolation of the curve in
Figure 2 for all domestic consumers.
The
strait
line
extrapolation of this curvo was used because the increase
in average load per consumer seemed to be approaching a
constant value
This condition would be represcnted by a
12
curve of constant slope, or the line represented by equatiox
(2).
At the end of a ten-year period, the average
energj use per consumer would be 971 kwh per month by
equation (1) and 837 kwh per month by equation (2).
figures indicate the load growth per consunier
2fld
These
are
independent of the £rowth in numbers of domestic consumers.
The increase in power requirements for existing large
eomniereial loads was based upon expansion plans of those
paz'tiotU.sr'
businesses
The expansion of other concen-
trated loads except irrigation was estimated according to
the type of business
arid
location,
The average estimated
increane in power requirements was between five and ten
per cent per year.
Irrigatton was considered as a single
concentrated load for each line section,
The increase in
this load was estimated according to the amount of irri-
gable land and available water in any one line section.
This estimate was independent of the number of consumers
connected to that line section.
The population increase in the rural areas was esti
mated at approximately three per cent per year as an average for the entire system.
Each line section was examined
as to the present consumer density and the
land sales or new home construction.
feasibility of
The increase in the numbers of commercial loads was
based upon applications or inquiries regardin
The large rural industrial loads in
usually
this service area are
awmi1is Qr rock crushing plants.
these industries is
1are1y
service.
The location of
detormined. b. th
topography
and hence their posftion with respect to the distribution
system is readily established.
The possible conversion ot
existing milis or crushers from gasoline or diesel engine
drive to electrical drive contributed the largest portion
to the estimated commercial load increase,
Advanced Load Study
Xn ordsr to provide a construction schedule and an
accompanying budget to supply adequately the increase in
system load, certain future timo periods were chosen as
design and construction dates.
These future time periods
were taken as two, five, and ten years in advance of the
"present" date,
A process by which the future system
design could be estimated would be to determine the substation, line, and line section loadin:
at the end of the
ten-year future period by the use cf the previously discussed estimating methods.
The necessary distribution
improvements to adequately serve the future loads would
then be determined.
The required system changes to meet
the two- arid five-year load estimates would be a portion
of the changos to fulfill the ten-year program.
It can readily be seen that if the above program is
carried out, at the end of
a
ten-year future period the
system would have reached its capacity.
Miy further
in-
crease in load or population growth would necessitate a
complete system change in the distribution and substation
facilities.
If the actual load increase was greater than
that estimated,
the system capacity would be reached in
less than ten years.
fourth load condition was used in this study, in
addition to the twa-, five-, snd ten-year estimates, so
that the above terminal design condition would be climi-
nated.
The value of 3000 kwh per month per domestic con-
sumer was chosen as an average use, and an increase in
consumers of 25 per cent of the number estimated for the
ten-year future period was taken as this fourth condition,
Io increase was assumed for the number of concentrated
loads, but the load requirement of these loads in the ten-
year future period was doubled to account for increased
commercial 1oadin.
an
extended'
with it,
Tuis fourth load condition was called
condition, as no
tie
element was coulcd
There was no dizect basis for choosing the
"extertdedt load conditions,
There are, however, several
line sections on this system that have a "present" average
kwh per month per consumer energy use in excess of 2000
during the winter months.
The controlling factor in the system design was that
in no placo on the distribution lines could the voltage
drop exceed seven per cent.
The system
opration for the estimated extended load
was first examined by determining the per cent voltage
arop at the end of each line section.
This was done using
data of the existing lines and transformers.
For this
condition, no additional diversity factors were applied to
the line section loads.
The system was then designed to
meet the voltage drop specifications by either changing the
conductor sise, or increasing the distribution voltage, or
by adding new substations to the system, or by the use of
any combination of the above tluee.
As this was to be the
terminal design condition, voltage regulators were also
included to assIst in reducing the voltage dz'op.
Several
alternata plans were calculated for each substation area by
changing substation locations and service area boundaries
until the prescribed service conditions could be tet with
a
minimum cost.
Line extensions were not included in this
study as they were assumed to be accounted for with the
increase in loading and numbers of conwumers on the main
branch feeders of each substation.
The ten-year future period was assumed to be much more
accurate for actual load prediction than the "extended"
procedure for system planning.
The straight line extra-
polated load curve of Figure 2 was used as the main guide
in determining the load for this period.
For the domestic
consumer load, the calculated average kwh per consumer per
month of the "present" system operation for each substation
was used as a base.
The average energy use of each lino
section was multiplied by the ratio of the average load
from equation two at Y equal to the twenty-fourth year to
the base quantity above,
This results in an average energy
use figure for each lino section that is in direct propor-
tion to the estimated energy use for the entire system.
The increase in the number of consumers for each line sec-
tion was calculated by the percentage thcrea8o as stated
in the section on Load and Population Growth stimates
The concentrated load values for this ten-year future
period were determined by the methods stated in the section on Load and Population Growth
The voltage drop due to
tI-ds
stimates.
estimated load was then
calculated at the end of each lino section on the basis of
the existing "presenti' lines and transformers.
These
results were then compared with those obtained in a similar manner for the ??extonded period. In determining the
voltae drop for this ten-year future perïod, ti same
17
diversity factors were used ai previou1y found in calcu1at1n
the bases
"present" system operation.
the sanie diversity factors,
it was
13y
using
aswned that the manner
of power use for each consumer would remain the same even
though the quantity used would increase.
The total system design for this load was then based
upon the design previously
alculatod ror the "extended"
condition with regard to eacb substation area and the
tern as
a whole,
sys-
Wire sizes, line phasing, and substations
were changed from the existing conditions to coordinate
with the "extended" requirements in reducing the maximum
oltae drop
aeen per
at any poiut in the system tQ the allowable
cent.
lu those areas adjacent to the substa-
tions and on ma3oz
feeders or tie lines, the improvement
as determined by the "extended" study were made to the
extent that the voltage arop at the end of the substation
boundarIes or tap feeders was not less than six per cent.
An example would be that a major feeder would have to be
changed from a number six eonductor to a number one nought
for 30 per cent of its length and to a number two conductor for an additional 50 per cent to raeet the "extende"
requirements.
To meet the
ten-year requirements, perhaps
the first 30 per cent would be changed to number one
nought with only 30 per cent changed to number two conductor.
This type of examination between the two studies was
18
continued throughout the eutire system.
In order to keep
the overall costs to a minimum, substation service areas
were changed so that improvements could be made in one
area but not neeeaari1y in the adjacent service area.
New substations were added when the necessary line improve
monts wuld exceed practical or economioal limits.
The new
substations would agree in location to those new ones a
determined by the "extended
study.
Exactly the sune procedure was followed in detorminthe necessary changos and improvements for the five-
year and two-year future load periods.
straiht line extrapolation
was used as a base,
In all eases, the
as represented by equation (2)
ßach study was compared with the
results of the studios made for the longer time periods in
the
same area.
To continuo the example quoted for the ten-
year period, this same feeder
miht
require that only the
first 30 per cent of its length be replaced by number one
nought conductor to meet the seven per cent voltage drop
naxiniurn in
the five-year period.
Voltage regulators were used sparingly in the two-,
five-, and ten-year system improvements as tiey are, in
most cases, only a temporary expedient.
Substation voltage
regulators were regarded as permanent devices and hence
were required for all substations at all times.
The
results of the des1ns for all future
were examined, and in some cases
improvements of the system
timo periode
readjusted such that
facilities
would be a
prores-
sive function from the "presentt
system to the "extended"
time period.
substation area
An
example for one
isiven
in the Appendix.
Utiljzation of the Advanced Load Study
the above study was being made, a cost analysis
was made for each of the alternate plans for system imAs
final choice of
the comparative cost fig-
provernent in each substation area.
The
the improvement plan rested on
ures. At the completion of the load study,
a
construction
cost schedule was drawn up for each of the time
periods involved. This schedule is used for budot estimating purposes and economical material purchasinß. Some
construction contract planning is also based on thes.
and
results.
Conclusions
least every
five years. portions of the system must be examined at
shorter time intervals duo to the inherent error in pre.
dieting load and population growth for a small portion at
This system study must be repeated at
a
large area.
20
The calculations revealed that for this sytez, with
7,200 volts line-to-neutral as the majority of ditributian voltage, a number one nought conductor was econorni-
cafly the largest conductor to use.
The amount of redue-
tian in voltage thop by using a l&rger conductor was
plotely OffSOt by the additiønal cost of material
labor to install it.
corn-
arid
In conjunction with this, it was also
determined that an approximate radius of seven miles was
the rnazirnum sexvice area for one substation if seven per
cent voltage drop was to be the rnaxirnim,
With
a
distribu
tion voltage of I1,4OO volts line-toneutral, this radius
increases to approximately twenty-four miles,
Within the two-year period after the data for this
study was taken, the load
,rowth on most of the substa-
tions agreed with the predicted load within ten per cent.
In sorne areas where single-phase line was ehanged to three-
phase line,
th
load growth was higher than predicted.
the caiculation* for the two-year
new substations were anticipated.
adunced program, two
One substction is
approximately one year behind the predicted time.
Pable I shows a tabulation of the number of substa-
tions required to serve the system as ealeulated in this
advanced plannin. study.
Zn
TABLE T
NUMBER OF SUBSTATIONS REUIRED
FOR SERVICE TO THIS SYSTEM
Advanced Planning
Period
Total
Substations
Number ot
Substations Added
Present
11
2Year
13
2
s-Year
16
3
10-Year
18
2
22
14
Extended
BIJ3LIOGRJUHY
1,
Goode, Harry H. and Robert
Ing.
2.
U.
L
New York, McGraw-Hill,
S. Dept.
of Agriculture.
Administration.
tables.
Systeu engineer-
Machal.
197.
3
p.
Rural Electrification
Technical Standaräs Division.
Washington, D. 0., August 1951.
(R.E.A. Bulletin no.
i42.)
29 p.
Demand
23
APPENDIX
The foU.owing is an illustration and explanation or
the development of the advanced planning for one substa-
tion area in this system0
Table II contains the legend
of map symbols as used in the following figures.
Figure
Lj.
is a map of this
area showing the distribu-
tion lines of this substation and connections to two other
substation systems,
section points.
The lettered points indicate the line
This figure shows the calculated voltage
drop at the major section point for three advanced plan-
ning periods and the **presentt period with line conditions
that exist under the "present" system.
The line is open
at point B as indicated by the gap at that point.
voltage drop at points
J,
The
K, and L exceed the seven per
cent maximum voltage drop for the "present" calculations
because voltage regulators that were
ifl
the system were
omitted in the ca1culationa,
Figure 5 shows the same system with the necessary
improvement for the "extended't operation.
The substation
delivery voltage has been changed from 7,200 volts line-
to-neutral to ]J,tOO volts line-to-neutral with all major
distribution lines converted to four-wire, three-phase
circuts.
The sections
to C and B to E are now to be
2I.
served from this substation to achieve
a
more economical
cost balance with respect to the two other substations that
could also serve these two line sections.
One voltage
regulator bank of three regulators has been included in
line section H to
The effect of the regulators has
J.
been taken into account in the voltage drop calculations
as shown on the map.
Figure 6 shows the system im:provernsnts necessary for
the ten-year future operation.
converted to
only
a
114,)I.00
The entire system has been
volts line-to-neutral voltage with
portion of the lines rephased from the present con-
ditlons.
seotion
No voltage regulators are necessary.
The line
B to C and B to E are to be served from thu
substation,
Figure 7
bows the system improvements necessary ror
the five-year futuro operation.
verted to
lLj.,tOO
The system has been eon-
volts iine-toneutral.
A very small
portion of the system must be rephased for satisfactory
service.
Figure 8 showi the system improvements necessary for
the two-year future oper*tion.
The system voltage is
7,200 volts line-toneutra1, as in the
A small portion of the
Une
section
"present't system.
system has been rephased with the
to E served from this substation,
Two
.
25
voltae reu1ator banks are included,
t
one in line section
to J, and one at section point B.
if the above figures are examined in reverse order,
a pzogress ive development of this system will result.
Th. tabulation in Table III illustrates this process.
26
TABLE
LEGEND
PERCENT
II
VOLTAGE
SYMBOLS
MAP
OF
DROP
PRESENT
IO
10.6913.691
YEAR
I
I
5
MILES
FROM
VOLTAGE
PERCENT
MILES
FROM
NUMBER
SUBSTATION
OF
DROP
SUBSTATION
CONDUCTORS
YEAR
ji.69(5.0I
I
[_l°
t
5.2
t
10.7
________
COPPER
VOLTAGE
GAP
OR
EQUIVALENT
IN
LINE
3
_______
1/1/
4 WIRE
THREE PHASE
_____
II
I I
SUBSTATION
PHASE
________
REGULATORS
OPEN
WIRE
2
SINGLE
1/"
CONDUCTOR
EXTENDED
A
WIRE
TWO
PHASE
II2.5I6 IL
20
IO
I
___
L
K_______
I(0.6
I2.4
IIT88I
6
He.r
i
0
6
3.
I
7.6 h1651
I}2.463.
L
[12.01
ii
6
I
H
O
G
6
I3.4110,cI
k
D
Is.6:1
t'
'6
6
B
to
H5HVLLE
CAP'
SLETZ
A
L2\6_
SS
10.6
11.41
1.114,81
C,
I
Io.'?61
To
7E00
Volfs
Line 10 Neuirdi
J
ToLo
METER
SILETZ
Figure
Fresetit
Sysferti
CONSUMERS
DRWG. BY
D. Ja
I: 2 MILES
SCALE:
___________________________
4-
POWER,
IDATE:
MÇ
JDRWG.
No.:
INC.
s,
%58
1284
28
6
L
643
2Z. 6
K
547
-
'9.7
0'
i'°
I
I
.
GI:
I
6
To
NßHV'LLE
ILET7
'z
A
CJ4,4
7L
To TOLEO0
Lnto
METER
SILETZ
Neutral
Figure
xteiided
Period
CONSUMERS
DRWG. BY
SCALE:
I:
D.
2
MILES
5
POWER,
DATE:
Mc
DRWG. NO
INC.
&, V358
1284
L
t22.61
K
I
4.60
118,71
6
IT
r;i
2.1
12.0
E
____
L0.
H
6
G
F
D
.
6
6
6
1-o
NAHV*LLE
SILETZ
A
r-0
46
Li
__
IIo41
J
To TOLEDO
(4,400
Ltie
to
Volts
METER
SILETZ
Neutral
Figure
Ten
'l'eQr
Future
Period
___________________________
CONSUMERS
DRWG. BY:
SCALE:
o.
2
MILES
6
POWER,
DATE:
1DRWG. No
INC.
B,
t958
f284
30
6
L
i
122.61
K
L
J61
iia.d
6
'J-
[ï4
112.01
I
2.2ql
E
io.7
I
I4
6
G
F
D
6
#
6
B
Ti;,
4jvut.c
SLET7
A
*6
A
O.'16
I2.441
J
To ToLEDo
14,400 Volts
Luie fo NeutrQ%
METER
SILETZ
Fsqure
Five '(ear
Future
Period
CONSUMERS
DRWG. BY
SCALE:
D.
":2
I
MILES
7
POWER,
INC.
DATE:
S,
M
IDRWG.NO.
I'958
I84
3'
'V'
L
16.qol
122.61
K
/ør4k
[le.?l
'V6
'7
ri
__
0
O31
L
t
I
f-4
#6
G
F
'--t
D
4
B
0
SLET7
A
A
0
GAP
C
t0,761
¡E
To TOLEOO
7200
VoLts
LLne fo Neutral
METER
SILETZ
Figure
TwoYear Future
Period
CONSUMERS
DRWG. BY
SCALE: I'
D.Jo4m5o
2
MILES
8
POWER,
IDATE:
MÇ
jDRWG. NO
INC.
3,
f558
i84
32
SYSTEM IM?ROVEMENTS FOR THE SILETZ
SUBSTATION AREA
Planning
Period
2-year
mImprovements for the Period Ifl4icated
Sincle-phase converted to two-phase
1.9 miles
Single-phase converted to three-phase
i.7 miles
Two-phase converted to three-phase
1.8 miles
No charu;e in wire size for the above rephasing
Add two regulator banks
Add additional line sections B to D and D to
s-year
Convert entire system to 1,4OO volts,
line -to-neutral
Add autotraneformer at substation
Add line section
to C
10-year
No chanes necessary
Eztsrided
Single-phase converted to three-phase
11.9 miles
Two-phase converted to three-phase
i1.8 miles
Change wire size, number six to number two,
three-phase
1 mile
Add one voltae regulator bank
33
Table XV illustrates the calculated
ubetation domand
in kilowatts and the avereçe kwh per month per consumer
Thr each planning period,
Those figures for the
prosentr
time are system data.
TABLE IV
AVERAGE KILOWATT-HOUR USE AND
SUBSTATION DEMAND
Averao kwh per month
Pia
Peri od
per Consumer
Pre sent
Substation Demand
in Kilowatts
2B
300
2-Year
714P3
560
5-Year
860
6140
10-Year
3. ,
0/40
860
Extended
3,000
2 , 850