SECTION: TITLE
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SHEET ( i ) OF (v)
DC SYSTEM
DESIGN GUIDE
FOR
DC SYSTEM
TATA CONSULTING ENGINEERS
73/1, ST. MARK’S ROAD
BANGALORE 560 001
FLOPPY NO
FILE NAME
: TCE.M6-EL-FP-DOC-006
: M6-6000.DWG
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PPD.BY
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RRN
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CKD.BY
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UAK
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UAK
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DATE
92-09-04
97-03-31
INITIALS
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99-03-02
FORM NO. 020R2
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TCE.M6-EL-7186000
SECTION:
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SHEET (ii ) OF (v)
DC SYSTEM
REVISION STATUS
REV. NO
DATE
R3
99-03-02
DESCRIPTION
1.Design guides for Lead Acid
battery-(M6-EL-BT-6000 R2),NiCad
battery (M6-EL-BT-6000A R1) and
battery
Chargers(M6-EL-BC-6004
R2) have been combined to make a
composite design guide on the ‘DC
System’.
2. In addition the loads considered
for emergency lighting , auxiliary
relays and indicating lamps have
been revised.
3.Section
4.0
providing
recommendation for quantities of
batteries in different installations has
been revised.
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CONTENTS
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SHEET (iii) OF (v)
DC SYSTEM
CONTENTS
PART-A
LEAD ACID BATTERY
SL.NO.
1.0
TITLE
SCOPE
SHEET NO.
2
2.0
TYPES OF LEAD ACID CELLS
2
3.0
SELECTION OF DC VOLTAGE LEVELS
3
4.0
QUANTITIES OF BATTERIES
5
5.0
AMPERE HOUR CAPACITY SIZING
6
6.0
INSTALLATION OF BATTERY
11
7.0
REFERENCES
13
APPENDIX-1 TYPICAL EMERGENCY LOADS
14
APPENDIX-2 RATING AND DESIGNATION
16
CAPACITIES AND DIMENSIONS OF TUBULAR CELLS
18
CAPACITIES AND FINAL CELL VOLTAGE OF HDP
TUBULAR CELLS AT VARIOUS RATES OF
DISCHARGE AT 27deg.C
19
CAPACITIES AT 27deg.C AT VARIOUS RATES OF
DISCHARGE OF TYPE II HDP CELLS (TUBULAR)
20
PERFORMANCE CURVES TYPE-II HDP CELLS
(TUBULAR)
21
CAPACITIES AND DIMENSIONS OF PLANTE CELLS
23
APPENDIX-3 BATTERY SIZING - SAMPLE CALCULATION
24
APPENDIX-4 TYPICAL BATTERY ROOM PLAN
31
SAMPLE WORK SHEET
32
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TCE.M6-EL-7186000
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CONTENTS
PART-B
NICAD BATTERY
SL.NO.
1.0
TITLE
SCOPE
2.0
DIFFERENT TYPES OF NICAD CELLS
35
3.0
PERFORMANCE CHARECTERISTICS
35
4.0
APPLICATIONS OF NICAD BATTERIES
38
5.0
MODE OF OPERATION
39
6.0
NUMBER OF CELLS
40
7.0
OTHER CONSIDERATIONS FOR SIZING NICAD
BATTERIES
41
8.0
INSTALLATION
42
9.0
BATTERY SIZING CALCULATIONS
43
10.0
SPECIFYING THE BATTERY
44
11.0
REFERENCES
45
APPENDIX-1 CELL DESIGNATION
SHEET NO.
35
46
PREFERRED DIMENSIONS
47
DISCHARGE DATA FOR NICAD BATTERY
(L,M & H TYPE CELLS)
48
TEMPERATURE CORRECTION
FACTOR CURVES
APPENDIX-2 SAMPLE CELL SIZING CALCULATION
CELL SIZING WORK SHEET
64
67
69
APPENDIX-3 COMPARISION OF NICAD BATTERIES
WITH LEAD ACID BATTERIES
71
SAMPLE WORK SHEET
72
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TCE.M6-EL-7186000
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DC SYSTEM
CONTENTS
PART-C
BATTERY CHARGER
SL.NO.
TITLE
SHEET NO.
1.0
SCOPE
75
2.0
RECOMMENDED PRACTICE
75
3.0
DISCUSSION
79
4.0
ENCLOSURES
i)
FLOAT CUM BOOST
CHARGER WITH
2 x 100% BATTERIES
ii)
iii)
TCE.M2-EL-CW-S-2631 R0
FLOAT CUM BOOST
CHARGER WITH
1 x 100% BATTERY
TCE.M2-EL-CW-S-2632 R0
FLOAT AND BOOST
CHARGER WITH
1 x 100% BATTERY
TCE.M2-EL-CW-S-2633 R0
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DC SYSTEM
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PART – A : LEAD ACID BATTERY
PART-A
LEAD ACID BATTERY
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PART – A : LEAD ACID BATTERY
1.0
SCOPE
This design guide outlines the recommendation for the determination
of voltage level, capacity, quantities and installation of DC battery of
lead acid storage type required for providing DC power supply to
essential services in the plant when the normal power supply fails.
This also gives consideration to the safe shut down of the plant as
well as human safety.
1.1
This section (Part –A) of this guide pertains to lead acid batteries and
also includes a few recommendations applicable to NiCad batteries
also like selecting voltage levels. The sizing criteria for Nickel
Cadmium batteries are dealt in Part – B of this design guide and
Part – C of this guide covers details about Battery chargers .
2.0
VARIOUS TYPES OF LEAD ACID CELLS
2.1
The plante type cells are more rugged, need less maintenance and
have a life expectancy of about 15-18 years, which is 5-7 years
longer than that for tubular type. However, the plante type battery is
costlier than the tubular type. All the manufacturers make tubular
cells while very few manufacturers make plante cell.
2.2
The cells with tubular plate construction are smaller in size than the
plante type for a given AH rating.
2.3
The following types of tubular cells are available in the market in
addition to standard variety :
a)
b)
c)
High Discharge Performance (HDP)
Maintenance Free-Valve Regulated (MF-VR)
Low-Maintenance (LM) type
2.4
The capacity of HDP cells under short duration discharge conditions
are higher than that of normal tubular batteries and are comparable to
that of Plante type batteries. Hence the capacity of battery required
will be smaller than that with the standard performance cells for
applications requiring high discharge currents for short duration.
Hence these cells are preferred for power plant applications.
2.5
The MF-VR cells require minimal attention from operation /
maintenance staff and are stated to need no topping up of distilled
water and no regular equalising charges. This type is well suited in
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PART – A : LEAD ACID BATTERY
the plants where organised maintenance is infrequent. The low
maintenance cells have grids made of low-antimony lead and require
topping up only once in a year or so even at higher float voltages like
2.25 VpC. Hence this type also is well suited for plants where
organised maintenance is infrequent or standalone substations in the
distribution system or medium or small scale industries or where
battery capacity is less than 300/500 AH.
2.6
The operating experience of the MF-VR and LM type cells for large
capacities is limited and very few manufacturers make the same.
Hence the sizing of these cells is not being discussed in the present
guide and use of these cells may be decided on case to case basis.
2.7
The recommended float voltage for lead acid batteries is between
2.16 V and 2.25V/ cell. The recommended boost charging duration is
10 hours in case of smaller capacity batteries and 14 to 16 hours for
larger capacities (1000 AH and above). The recommended maximum
boost charger voltage is 2.75 V/cell. The recommended equalising
charge voltage is 2.33 VpC.
3.0
SELECTION OF DC VOLTAGE LEVELS
3.1
The voltage level selection for the plant shall consider the following
aspects :
3.2
a)
Quantum of power
b)
Individual load point power ratings, quantum of such load points
and the geographic spread of the load points
c)
Standard voltages suitable for the equipment
For the same power requirement, the battery room size, and battery
cost with higher voltage will be higher than those with lower voltage.
However, the lower voltage requires higher current for the loads and
hence to meet this current and to limit the voltage drop within limits
cable sizes will be higher than those with higher voltage. Considering
all the aspects following voltage levels are recommended.
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PART – A : LEAD ACID BATTERY
3.2.1 Power Plant
3.2.1.1 Large power plants (Coal based)
a)
For electrical power,
control & protection
requirements
-
b)
I&C system
Normally most of the I&C
vendors' systems are suitable
for +24V or 48V DC.The
voltage level shall be fixed
after I&C system requirement
is finalised.
c)
Isolated auxiliary plants
-
30 V DC or 110 V DC like raw
water pump house (dedicated
battery if running lengths of
cables from the main plant is
comparatively much higher)
d)
Switchyards
-
220 V DC (If switchyard has
got separate control building)
e)
Coal handling plant
-
110 V DC/220 V DC
3.2.1.2 Gas based/diesel/Hydro
-
110 V/220 V DC power plants
including captive power
plants
3.2.2
220 V DC
Industrial Plants
a)
Large plants with many
load points and distributed
in large area
220 V DC
b)
Small plants with
multiple load points and
outdoor substations
110 V DC
c)
Small plants with very
few switchboards / load points
30 V DC
d)
For process control
Generally 24/48V (As
required by the I&C system
design)
-
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PART – A : LEAD ACID BATTERY
4.0
4.1
4.1.1
4.1.2
QUANTITIES OF BATTERIES
Power Plants
a) In case of unit sizes upto 250 MW, each unit shall be provided
with one battery and also, a separate battery shall be provided
for the common services of these units and switchyard load. The
unit and common services batteries shall be sized to cater one
unit and station service loads so that one serves as a standby to
the other.
b)
For instrumentation and control system two 100% batteries for
each unit shall be provided.
c)
If switchyard is having a separate control building one 100%
battery shall be provided for the switchyard. In addition
switchyard DCDB will be provided with a tie feeder from station
DCDB (as a standby).
d)
One no. 100% rating battery shall be considered for coal
handling plant DC power requirements.
For large power units (500 MW and above) and nuclear power plants,
for each unit, the 220V DC unit loads shall be divided into two
categories, e.g.
a)
D.C. power loads comprising D.C. motor drives, solenoids,
emergency lighting , etc.
b)
D.C. control loads comprising tripping and closing circuits,
indicating lamps, protection and control panels, safetysupervisory systems etc.
Each category of loads will be catered to by a separate 220V battery
and battery charger system. There will be three 50% rated
batteries.Each battery is capable of catering to 50 % power loads of
unit ( since the power load requirement of 500MW unit is very huge )
and entire control load of unit. Normally two of the three batteries will
cater power loads and the third one will be catering control loads.
For switchyard load there will be a seperate 100% battery feeding
switchyard loads.It is recommended to provide a tie from DCDB of
control loads to DCDB of switchyard. One number 100% battery shall
be considered for coal handling plant DC power requirement.
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PART – A : LEAD ACID BATTERY
4.1.3
Gas Power Plants
The battery and charging equipment for each gas turbine is supplied
by gas turbine supplier as part of the package.It is recommended to
have each unit battrery rated to cater two gas turbine units.and a tie
feeder is provided between one unit DCDB to another unit DCDB.
The station and STG DC loads shall be catered by provision of
2X100% batteries .
If switchyard and station building is seperate from the main plant
control building a seperate 1X 100% dedicated battery shall be
recommended.
For catering I&C loads , it is recommended to have 2X 100% rated
batteries for each unit.
4.1.4
Separate batteries with chargers are required to be provided for UPS
for power plants. For details please refer to design guide M6-CL-AUG-715-6011 for UPS.
4.2
Industrial Plants and Small Power Plants
Two 1X 100% rated batteries to cater for all the emergency power,
control and protection requirements of the plant. Shall be provided.
However, it shall be firmed up based on the quantum of the load
points and their geographic location.
A separate battery may be required for instrumentation, control and
annunciation requirement for process purposes. The specific
requirements in each case shall be ascertained.
Separate batteries with chargers are required to be provided for UPS
for Industrial and Small power plants. Possibility of using the same
station battery for UPS as well may be explored on a case to case
basis.
4.3
The recommendations on quantities are included int Part – C of this
design guide in Tabular form.
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PART – A : LEAD ACID BATTERY
5.0
AMPERE HOUR CAPACITY SIZING
5.1
The capacity of a cell or battery as defined in Indian standards 1651
& 1652 is expressed in Ah, at 27deg.C, attainable when the cell or
battery is discharged at the 10-hour rate to an end voltage of 1.85 V
per cell. The capacity is a function of number of positive plates per
cell.
5.2
The battery capacity is influenced by the factors listed below.
a)
b)
c)
d)
e)
5.2.1
Duty cycle
End of the duty cycle voltage
Temperature correction factor
Compensation for ageing
Design margin
Duty cycle
a)
At the time of power supply failure, the battery is required to
supply D.C. power requirements of essential circuits for safe
shut down of the station, vital instrumentation, controls,
communication system, DC annunciation and emergency
lighting.
b)
In power plants and some industrial plants an emergency diesel
generator is available, which will provide a.c. power to the
battery charger after the period required to start and connect it
to the emergency AC bus. However, the battery size shall be
calculated on the assumption that the engine driven generator
may fail to start or operate satisfactorily.
c)
The duration for which each type of D.C. load will have to be
supplied by battery when the normal power supply fails is
different. The same may be continuous or for short time duration
or momentary. In a typical power plant the DC power, control &
protection loads and their classification based on duration for
which they need to be supplied are as follows.
Time duration
i)
Upto 1 minute
Loads (Amperes)
*
Trip relay / Trip coil currents of
circuit breakers.
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PART – A : LEAD ACID BATTERY
*
Starting currents of all
automatically started D.C.
motors.
*
DC motor operated emergency
steam stop valves.
*
Solenoid valves for isolation,
safety relief, minimum
recirculation etc.
*
Inrush currents of supervisory
safety system for fuel, turbine
and generator controls.
ii)
Upto one(1) hour
*
*
*
Emergency oil pump
Jacking oil pump
Steam generator control panels
(including FSSS, Mill panels)
iii)
Upto two(2) hours
*
*
*
*
*
D.C. seal oil pump
Scanner air fan
D.C. emergency lighting
P.A. system
Annunciation (20%)
iv)
Upto 10 hours
*
*
*
•
d)
Indicating lamps / Semaphore
indicators in switchgears/control
panels
Control room emergency lighting
Annunciation (10%)
Auxiliary relay ( which are likely
to be energized during black out
condition )
A table of loads indicating their power requirement and duration
shall be prepared and a load curve for the battery shall be
established. Appendix-1 indicates a table for typical emergency
DC loads. Appendix-3 indicates a list of equipment and their
typical D.C. loads for a 210 MW unit. It is recommended that
project specific loads for DC motors, T.G. & S.G. vendor loads
and inrush currents shall be obtained before proceeding with the
sizing.
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PART – A : LEAD ACID BATTERY
e)
5.2.2
I&C battery for power plant application shall be sized to cater
the loads for half hour. The loads to be considered shall be the
maximum load of I&C system at any operating condition viz
starting, running and tripping/stopping.
End of duty cycle voltage
a)
The allowable end of duty cycle voltage of a battery has a major
role in determination of the capacity of the battery. This in turn is
dependent on the limits of system voltages that can be
withstood by D.C. equipment. The D.C. equipment are generally
rated to operate between +10% and -15% of their rated value
with certain exceptions like trip coils and trip relays which can
accept lower voltages.
b)
Manufacturers recommend a float voltage ranging from 2.06V to
2.3 volts per cell, for different float voltage adopted, the required
frequency of equalising charges are given below.
-----------------------------------------------------------------------------------Float Voltage Per Cell
Approximate
periodicity of
equalising charges
----------------------------------------------------------------------------------2.25
No equalising charges
2.20
12 months
2.15
3 months
2.10
1 month
2.06
2 weeks
---------------------------------------------------------------------------------
c)
It is desirable to keep the float voltages as high as the D.C.
system can accept to minimise frequency of equalising charges.
It is recommended to keep a float voltage of 2.2V per cell.
However, this shall be confirmed from the battery supplier
specific to the project.
i)
ii)
Considering the above, the number cells of a battery are
selected as :
Max.allowable DC voltage - Regulation due to charger
--------------------------------------------------------------Float voltage per cell
The end of duty cycle cell voltage is determined
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PART – A : LEAD ACID BATTERY
by
Min. allowable D.C. voltage + Cable drop
------------------------------------------------No. of cells
d)
Sl.
No
1
2
Typical values for 220V DC system and 24V DC systems are
given in the table below:
System
Max.allow Min.allowable No.of End of duty cycle
voltage
cells
voltage
able
voltage
220V
242V
187V
108
1 min - 1.75V /
cell 1,2 HRS &
10 hours 1.85V/cell
24V
30V*
21.5V*
13
1.8V/cell
* To be ascertained on project to project basis
Note : For 110V & 30V plant DC systems, the details can be worked
out in the same manner as for 220V system above.
5.2.3
e)
The cable drop to be considered in DC system shall be 2% from
the charger/battery to Distribution board and 3% from board to
any feeder in case of 220V DC system.
f)
In case of 24V DC system to keep the voltage drop
within 5% limit, the cable sizes between DC board and I&C
cabinets are very large and sometimes impractical to terminate.
Hence for 24V system a total drop of 7.5% (2.5% between board
and charger/battery and 5% between board and individual
loads) is recommended.
Temperature correction factor
The standard temperature for stating cell capacity is 27deg.C. If the
lowest expected electrolyte temperature is below 27deg.C, a cell
large enough to have the required capacity available at the lowest
expected temperature shall be selected. The lowest electrolyte
temperature shall be considered as 10o above minimum ambient
temperature. If the lowest expected temperature is above 27deg.C,
no correction factor shall be applied. The correction factor shall be
calculated according to the formula:
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PART – A : LEAD ACID BATTERY
Correction factor
=
/
K
\
for the lowest
| 1 + -------- (27-T) |
expected electrolyte
|
100
|
temperature, Tdeg.C
\
/
The factor 'K' for plante cells is 0.9 and for tubular, 0.43. The
minimum electrolyte temperature (T) shall be considered as 10deg.C
higher than the minimum ambient air temperature at site.
5.2.4
Compensation for age
ANSI/IEEE STG.450-1270 recommends that a battery be replaced
when its actual capacity drops to 80% of its rated capacity. Hence a
factor of 1.25 shall be considered for ageing.
5.2.5
Design margin
When the D.C. loads are more or less final at the time of battery
sizing for tender specification purposes and/or the battery sizing is
being done for a similar plant already executed, no design margin is
considered necessary. If the sizing is being done for a new type of
project or with very little confirmed loads, a design margin of 10 to
15% shall be provided over the final capacity arrived.
While sizing the battery for nuclear power plant applications, it shall
be noted that the "margins" required by IEEE STD.323-1273. 6.3.15
& 6.3.3 are to be applied during "Qualification" and are not related to
"design margin".
5.3
Calculation of Ampere Hour Capacity
The plante and tubular high discharge performance cells have better
capacity factors at the short duration discharges (1 hour, 2 hours
etc.). For durations less than one hour, the above types of cells have
higher capacity factor than the tubular standard discharge
performance cell. Hence for power plant application and for
applications where short duration loads are appreciable high
discharge performance cell shall be used.
The capacity of the battery shall then be determined in accordance
with the procedure outlined in Appendix-3.
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PART – A : LEAD ACID BATTERY
6.0
INSTALLATION
6.1
Battery cells shall be installed in a separate battery room, preferably
near the D.C.load. The 24V batteries shall be in the same floor as
I&C cabinets and as near as possible. Fig.4 included in design guide
TCE.M6-EL-PJ-G-SG-6602 R1 (GA of Turbine Building Electrical
Equipment & Space Organisation) indicates a typical battery Room
Plan (Copy of Fig.4 enclosed as Appendix-4 for ready reference).
6.2
The flooring shall be provided with acid resistance tiles, a dished
floor drain and drainage piping for collecting spilled acid. The spilled
acid shall be diluted before discharging to the outside storm water
drainage system.
6.3
Acid proof paint shall be provided on walls upto 2.3m height.
6.4
A wash basin shall be provided for emergency drenching of face and
body.
6.5
The total capacity of exhaust fans (suitably distributed) should be
minimum 1/10th of the total volume of the battery room per minute.
The exhaust shall be directly outside the building. However, specific
requirements shall be obtained from the battery manufacturer.
6.6
Separate cable(s) shall be provided for each polarity of the outgoing
battery leads. If the cables are unarmoured they shall be taken in
separate conduits and the conduits shall be PVC coated for
protection against corrosion. Routing of any cables in cable-trays
through battery room shall be avoided.
6.7
Adequate provision for storage of acid, distilled water, instruments,
accessories, etc. should be provided in the battery room.
6.8
During float or boost charging of the lead acid battery hydrogen gas
is generated. The volume of hydrogen gas generated depends on the
amount of charging current. Also, the float current demand of a fully
charged battery will double approximately for every 10deg.C rise
above the base temperature of 27deg.C. Each fully charged cell
produces 4.5 x 10-4 Cu.m (0.016 Cu.pt) hydrogen gas per hour per
charging amperes in an ambient of 25deg.C to 27deg.C. Hydrogen
explosive concentration is reached if the explosives mixture is three
percent of the volume of room air.
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PART – A : LEAD ACID BATTERY
6.9
In view of the presence of hydrogen gas, warning signs shall be
installed outside and inside the room prohibiting smoking, sparks of
flame.
6.10
Lighting fixtures shall be vapour-proof type with reflectors painted
with anticorrosive epoxy-paint. Lighting switch should be outside the
battery room.
7.0
REFERENCES
7.1
IS:1651-1991
:
Stationary cells and batteries,lead-acid type
with Tubular positive plates Specification.
7.2
IS:1652-1991
:
Stationary cells and batteries, lead-acid
type with Plante' positive plates
Specification.
7.3
IEEE Std 485-1273 :
Recommended practice for sizing large lead
acid storage batteries for Generating
Stations and Sub-stations.
7.4
IS:8320-1272
:
General requirements and methods of tests
for lead-acid storage batteries
7.5
IS:1885-1965
:
Electrotechnical vocabulary Secondary cells and batteries.
7.6
IEEE Std. 450-1270 :
Recommended practice for maintenance
testing and replacement of large lead
storage batteries for generating stations and
sub-stations.
7.7
IEEE Std. 484-1271 :
Recommended practice for Installation
design and installation of large lead storage
batteries for generating stations and substations.
7.8
IEEE Std. 323-1273 :
IEEE Standard for Qualifying class-1E
Equipment for Nuclear Power Generating
Stations.
ISSUE
R3
FORM NO. 120 R1
SECTION:
APPENDIX - 1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SHEET
DC SYSTEM
14
OF 79
PART – A : LEAD ACID BATTERY
APPENDIX-1
TYPICAL EMERGENCY LOADS
1
a) Bearing oil pump
b) Bearing oil pump for BFPT
c) Bearing oil pump for MBFP
STEAM TG
500MW
120MW
13kW
15kW
2x5.5kW --11kW
---
2
a) Seal oil pump
b) Seal water pump for BFPS
13kW
60kW
10kW
---
11kW
---
3
Jacking oil pump
35kW
37KW
28KW
4
Scanner air fan
----
4.4KW
7.5KW
5
Inverter for instruments
5kW
10kW
6
Inverter for PA system
2kW
2kW
2kW
7
Carrier panels
<-----------
8
Auxiliary relay (each)
<-----------
150watt/ --------->
panel
3watts
--------->
9
Auxiliary contactor (each)
<-----------
10watts
--------->
10
DC emergency lights
<-----------
Approx.
10% of
normal
lighting
--------->
11
UPS load (Incl. DAS,
transmitters, controllers)
55kVA
45KVA
30kVA
210MW
13kW
-----
.
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX - 1
SHEET
15
OF 79
PART – A : LEAD ACID BATTERY
APPENDIX-1 (Cont’d)
TYPICAL EMERGENCY LOADS
500MW
STEAM TG
120MW
210MW
1
Continuous Loads
Annunciator window (each)
2
Indicating lamp (each)
ß -----5-10W For filament type ----à
ß ----1 W For cluster LED type type ---à
3
Auxiliary relays (each)
<--------------------3W--------------------------à
4
Auxiliary contactors (each)
<--------------------10W-----------------------à
5
Semaphore indicator (each)
<--------------------3W------------------------à
6
Control room emergency
lighting
<---------------------1kW---------------------à
7
FSSS load
ß-------------------10kW---------------------à
ß---------------------5W -----------------à
NOTES:
1.
The data for 120MW and 210MW units are taken from the designed
data for GIPCL and Bhatinda units. All DC motor loads,
electromagnetic valve loads, FSSS loads, instrumentation & control,
UPS loads, other turbine generator supervisory loads should be as
far as possible ascertained from the manufacturers.
2.
When starting currents of DC motors are not available it may be
assumed as 3.5 x FL current. If step resistor starting is provided the
starting current may be assumed as 2.5 x FL current.
3.
Instrumentation and control loads and annunciation loads may be on
a separate 48 V / 24V battery.
4.
For 210 MW unit loads also refer Appendix-3.
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SECTION:
APPENDIX-2
SHEET
DC SYSTEM
16
OF 79
PART – A : LEAD ACID BATTERY
APPENDIX-2
CELL DATA
RATING AND DESIGNATION
1
Ampere-Hour Rating
The rating assigned to the cell shall be the capacity expressed in
ampere-hours (after correction to 27deg.C) stated by the
manufacturer to be obtainable when the cell is discharged at the 10hour rate (C10) to a final voltage of 1.85 voltage.
2.
Designation
The cell shall be designated by symbols given below, arranged in the
following sequence :
Type of Positive
Plate
(See 2.1)
Ah Rating
of Cell
(See 2.2)
Type of
Container
(See 2.3)
Notes:
1.
The plates are not replaced in this type of construction
therefore, this designation does not include the number of
positive plates; and
2.
The designation of partially plated cells is not being
standardized because partial plating of cells in this type of
construction is not done.
2.1
The positive plates shall be designated by the letter 'T' for tubular
and 'P' for plante.
2.2
The capacity rating shall be indicated by a number equal to the
capacity in Ah.
2.3
The material of container shall be designated by any one of the
following letters as the case may be :
G - for glass;
H - for hard-rubber;
P - for plastics;
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-2
SHEET
17
OF 79
PART – A : LEAD ACID BATTERY
W - for wood, lead-lined; or
F - for fibre reinforced plastics (FRP)
Example : T 400H HDP - designates a high discharge performance
cell having tubular positive plates and a capacity of 400 Ah at 10 hour
rate in hard-rubber container. SOURCE : IS 1651 & 1652 - 1991
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-2
SHEET
18
OF 79
PART – A : LEAD ACID BATTERY
APPENDIX-2 (Cont’d)
CELL DATA
Capacities and Dimensions of
Tubular Cells
----------------------------------------------------------------------------------------------Capacity at
Maximum Overall Dimensions
10-Hour Rate ---------------------------------------------------------------------Length
Width
Height
(1)
(2)
(3)
(4)
Ah
mm
mm
mm
--------------------------------------------------------------------------------------------20
105
170
365
40
105
170
365
60
140
170
365
80
165
190
365
100
190
190
450
120
190
190
450
150
190
190
550
200
265
215
550
300
320
215
550
400
380
215
550
500
390
235
550
600
390
235
715
800
515
235
715
1000
515
300
750
1500
450
400
865
2000
500
450
865
2500
650
450
865
4000
900
480
1240
5000
900
480
1240
6000
900
500
1240
7000
1100
500
1240
8000
1100
500
1240
--------------------------------------------------------------------------------------------NOTES :
1.
The length and width dimensions given in this table may be
interchanged.
2.
In the case of batteries with built-in cell connectors, the height of
the interconnector shall be disregarded.
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-2
SHEET
19
OF 79
PART – A : LEAD ACID BATTERY
3.
For capacities not covered in this table, the cell dimensions shall
not exceed the dimensions of the cell of next higher size covered
by this table.
SOURCE : IS 1651 - 1991
APPENDIX - 2 (Cont’d)
Standard Discharge Performance Cells (Tubular)
Capacities and Final Cell Voltage
at various rates of discharge at 27deg.C
------------------------------------------------------------------------------------------Period of Capacity Ratio :
Capacity
Final
Discharge Ah capacity (CT)
Rating Factor
Cell
Hours (T) divided by the 10hr (KT) = (1/2)
Voltage
Rated capacity (C10)
(Volts)
(1)
(2)
(3)
(4)
--------------------------------------------------------------------------------------------1
0.500
2
1.75
2
0.633
3.16
1.78
3
0.717
4.18
1.80
4
0.782
5.12
1.81
5
0.833
6.00
1.82
6
0.879
6.83
1.83
7
0.917
7.63
1.83
8
0.950
8.42
1.84
9
0.979
9.19
1.84
10
1.0
10
1.85
-------------------------------------------------------------------------------------------Source : IS 1651-1991
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SECTION:
APPENDIX-2
SHEET
DC SYSTEM
20
OF 79
PART – A : LEAD ACID BATTERY
APPENDIX - 2 (Cont’d)
CELL DATA
Capacities at 27deg.C at various rates of discharge
Type II High Discharge Performance (HDP) Cells (Tubular)
------------------------------------------------------------------------------------------------Period of Capacity Ratio :
Capacity
Final Remarks
Discharge Ah capacity (CT)
Rating Factor Cell
Hours (T) divided by the 10hr (KT) = (1/2) Voltage
Rated capacity (C10)
(Volts)
(1)
(2)
(3)
(4)
------------------------------------------------------------------------------------------------1/60 (1 min)
0.022
0.76 1.75 } M/s Chloride
1/2 (30 min)
0.368
1.36 1.75 } India
1
0.60
0.488
0.392
1.67
2.05
2.55
1.75
1.80 } M/s Chloride
1.85 } India
2
0.738
0.714
0.597
2.71
2.80
3.35
1.78
1.80 } M/s Chloride
1.85 } India
3
0.811
3.77
1.80
4
0.862
4.13
1.81
5
0.90
5.55
1.82
6
0.93
6.45
1.83
7
0.951
7.361 1.83
8
0.971
8.239 1.84
9
0.988
9.109 1.84
10
1.0
10.0 1.85
---------------------------------------------------------------------------------------------Source : IS 1651-1991 & Capacity Rating curves from M/s Chloride India.
NOTE : The above data is applicable for plante cells also. The capacities for
Type-I HDP cells are same as above for discharge rates of 3 hour, 5
hour and 10 hours (ISS does not specify capacities at other
discharge rates for Type-I cells).
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-2
SHEET
21
OF 79
PART – A : LEAD ACID BATTERY
TYPICAL CELL PERFORMANCE CURVES (SH-1)
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-2
SHEET
22
OF 79
PART – A : LEAD ACID BATTERY
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-2
SHEET
23
OF 79
PART – A : LEAD ACID BATTERY
APPENDIX - 2 (Cont’d)
CELL DATA
Capacities and Dimensions: Plante Cells
----------------------------------------------------------------------------------Capacity at
Maximum
Overall
Dimensions
10-Hour Rate ---------------------------------------------------------Length
Width
Height
(1)
(2)
(3)
(4)
Ah
mm
mm
mm
----------------------------------------------------------------------------------20
130
140
225
40
205
140
225
60
205
140
225
80
175
235
370
100
175
235
370
120
175
235
370
150
175
235
370
200
210
235
370
300
290
235
370
400
365
235
370
500
375
310
625
600
375
310
625
800
375
335
625
1000
385
375
635
1500
520
390
635
2000
650
390
635
2500
785
405
130
4000
1160
405
130
5000
1350
515
650
----------------------------------------------------------------------------------NOTES :
1.
The length and width dimensions given in this table may be
interchanged.
2.
For capacities not covered in this table, the cell dimensions shall
not exceed the dimensions of the cell of next higher size covered
by this table.
Source : IS 1652-1995
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-3
SHEET
24
OF 79
PART – A : LEAD ACID BATTERY
BATTERY DUTY CYCLE DIAGRAM
L
4
=
9
0
0
A
L6 = 84 A
L5 = 186 A
L3 = 46A
L2 = 30A
L1 = 13 A
SECTION-1
60
1
120
600
SECTION-2
SECTION-3
SECTION - 4
DURATION ( MIN )
ISSUE
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FORM NO. 120 R1
SECTION:
APPENDIX-3
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SHEET
DC SYSTEM
25
OF 79
PART – A : LEAD ACID BATTERY
APPENDIX - 3
SAMPLE CALCULATION FOR SIZING OF A THERMAL POWER
STATION 220V UNIT BATTERY (210 MW)
LOAD TABULATION
Sl.
no
Load description
Qty.
Rating
Watts
1 min
1 hr.
I.
UNIT LOADS
1.
Tripping loads ( Prot. Relay + Trip Relay + CB Trip coil )
a.
6.6 kV CBs
34
300
10,200
b.
415 V CBs
7
250
1,750
2.
Turb. Generator
a.
E.O.P.
1
13,000
32,500*
13,000
b.
DC seal oil pump
1
11,000
27,500*
-
c.
Jacking oil pump
1
28,000
70,000*
28,000
d.
Others
2,000
2,000
3
Steam generator
10,000
-
2hrs.
10 hrs.
11,000
10,000
DC CSP (includes
FSSS, mill panel)
4.
Main steam stop
valve
2
4,000
10,000
5.
Scanner air fan
1
7,500
18,750 *
-
7,500
6.
Emergency lighting
-
-
5000
7.
Indicating lamps
400
1#
8.
Annunciation
windows
10
5
9.
Auxiliary relays
LS
LS
1000
400
100
50
600 (200
nos @ 3W
each )
ISSUE
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FORM NO. 120 R1
SECTION:
APPENDIX-3
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SHEET
DC SYSTEM
26
OF 79
PART – A : LEAD ACID BATTERY
II
STATION LOADS
1.
Tripping loads
6.6 kV CBs
70
300
21,000
415 V CBs
12
250
3,000
2.
Indicating lamps
500
1 #
3.
PA system
LS
LS
4.
Auxiliary relays
LS
LS
500
2,000
300
(100 nos
@3W
each )
TOTAL AMPS
894
232
116
13
*
#
Starting currents of motor ( 2.5 times the rated current )
Cluster LED type indicating lamps
2.0
SIZING CALCULATION
2.1
Battery duty cycle diagram in Sh.24 is constructed as detailed below
from the above DC emergency load list for a typical 210 MW unit.
2.2
Analysis of load data in Sh.25&26 indicates the distribution of loads
with duration as under :
Load
Sl.
no
Duration
1
0 – 10 hrs.
2850 W
13A
2
1 min. - 2 hrs.
(11000+7500) =18500W
84A
3
0 – 2 hrs.
(5000-1000) + (100- 50) +
2000 = 6500W
30A
4
1 min. - 1 hr.
(28000+13000) = 41000 W
186A
5
0 – 1 hr.
(51000 -(13000+28000))
=10000 W
46A
6
0 - 1 min.
196680 W
894A
In Watts
in Amperes
NOTE: These loads are arrived at taking care to see that loads are not
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-3
SHEET
27
OF 79
PART – A : LEAD ACID BATTERY
repeated under the same time duration , for example in (0-1hr) load
duration the load would be (51000-(13000+28000))=10000,
(13000+28000) being subtracted from the total load as the same is
already considered under (1minute -1hr )load.
2.3
The cell sizing data that will be useful in filling out the cell sizing work
sheet is derived from the duty cycle diagram and tabulated as below :
Cell sizing data
--------------------------------------------------------------------------------period
Loads
Total Amperes
Duration (min)
---------------------------------------------------------------------------------
2.4
1.
L1+L2+L3+L4
983
1
2.
L1+L2+L3+L5+L6
359
59
3.
L1+L2+L6
127
60
4.
L1
13
480
-------------------------------------------------------------------------------Capacity rating factors (KT) are derived from the table for HDP, Type
II tubular lead acid cells enclosed in Appendix-2. (These can be read
from the curves enclosed in Appendix-2 also).
2.5
Sh.29 &30 shows the way in which the cell sizing work sheet and the
KT rating factor would be used to size the battery for the duty cycle
indicated.
2.6
Design margin
Considered as 1.0 since the loads for 210 MW thermal power plant
are well established.
2.7
Temperature correction factor :
Minimum ambient temperature for the installation is 7deg.C. Hence,
the lowest expected electrolyte temperature to be considered (in
accordance with cl.5.2.3) is 17deg.C (=7deg.C+10deg.C)
Temperature correction factor to be applied
0.43 (27-17)
= 1 + ----100
= 1.043
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-3
SHEET
28
OF 79
PART – A : LEAD ACID BATTERY
NOTES :
1.
Tubular cell type HDP-II is considered in the above sample
calculation as the duty requires the cells to deliver high discharge in
short duration (1 hr). However, the same procedure as above can be
followed for sizing the battery using HDP Type-I or standard
discharge performance cells. Data on cell capacities at varying
periods of discharge for standard discharge performance type cells &
for Type-I HDP cells is enclosed in Appendix-2.
2.
If plante cells are being sized, the data on capacities for Type II HDP
cells enclosed in Appendix-2 can be used sizing procedure also
remains same except the value of 'K' in formula for temperature
correction factor (Refer cl.5.2.3).
3.
Typical DC emergency loads for a 210 MW unit are considered for
the sample calculation above. In case the load cycle diagram for a
particular installation happens to be more complex than the one in the
sample calculation above, IEEE 485-1273 may be referred for further
guidance.
ISSUE
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FORM NO. 120 R1
SECTION:
APPENDIX-3
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SHEET
DC SYSTEM
29
OF 79
PART – A : LEAD ACID BATTERY
Project :
Date :
Lowest Expected
Electrolyte Temp : 17oC
(1)
Period
(2)
Load
(Ampe
res)
Minimum 1 Min.:1.75V DC
Cell Voltage : Others: 1.85V DC
Cell Chloride
Mfg. : India
Cell Tubular
Type : HDP, Type-II Sized By : RRN
(3)
(4)
(5)
(6)
(7)
Change in
Load
(Amperes)
Duration
of Period
(minutes)
Time to
End of
Section
(minutes)
Capacity
at T Min.
rate
K Factor
(KT)
Required Section Size or
(3)x(6B) = Rated AH
Pos Values
Neg.Value
LOAD DATA :
A1= 983 A,
M1= 1 Min;
A2 = 359 A,
A3= 127 A,
M3= 60 Min;
A4 = 13 A,
A5= A,
M5= Min; A6 = A, M6 = Min.
M2 = 59 Min.
M4 = 480 Min.
Section - 1: First Period only - If A2 is greater than A1, go to Section-2
1
A1=983
A1-0=983
M1=1
T=M1=1
Sec.-1
Section - 2: First Two Periods only - If A3 is greater than A2, go to Section-3
1
A1=983
A1-0=983
M1=1
T=M1+M2=60
2
A2=359
A2-A1= -624
M2=59
T=M2=59
Sec.-2
Section - 3: First Three Periods only - If A4 is greater than A3, go to Section-4
1
A1=983
A1-0=983
M1=1
T=M1+...+M3=120
2
A2=359
A2-A1= -624
M2=59
T=M2+M3=119
3
A3=127
A3-A2= -232
M3=60
T=M3=60
Sec.-3
Section - 4: First Four Periods only - If A5 is greater than A4 go to Section-5
1
A1=983
A1-0=983
M1=1
T=M1+...+M4=600
2
A2=359
A2-A1= -624
M2=59
T=M2+...+M4=599
3
A3=127
A3-A2= -232
M3=60
T=M3+M4=540
4
A4=13
A4-A3= -134
M4=480
T=M4=480
Sec.-4
Section - 5: First Five Periods only - If A6 is greater than A4 go to Section-6
1
A1=
A1-0=
M1=
T=M1+...+M5=
2
A2=
A2-A1=
M2=
T=M2+...+M5=
3
A3=
A3-A2=
M3=
T=M3+...+M5=
4
A4=
A4-A3=
M4=
T=M4+M5=
5
A5=
A5-A4=
M5=
T=M5=
Sec.-5
0.76
Total
747
747
2.55
2.55
Sub Total
Total
2507
3.35
3.35
2.55
Sub Total
Total
3293
10
10
9.1
8.2
Sub Total
Total
9830
2507
916
3293
611
9830
544
Sub Total
Total
***
***
1591
1591
***
2090
592
2682
***
6240
2111
935
9286
***
***
Section - 6: IF LOAD CYCLE HAS MORE THAN 5 LOAD PERIODS, CONTINUE FURTHER IN SIMILAR MANNER.
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-3
SHEET
30
OF 79
PART – A : LEAD ACID BATTERY
Section - 7: Random Equipment Load only (if needed)
R
AR=
AR-0=
MR=
T=M+R=
Section - 8:
Maximum Section Size = 916
Section - 9:
Random Section Size = -
Section - 10:
Temperature Correction Factor = 1.043
Section - 11:
Design margin = 1.0
Section - 12:
Aging Factor = 1.25
Section - 13:
Uncorrected size = (8) + (9)= 916+ - = 916
Section - 14:
All capacity required = (13) x (10) x (11) x (12) = 916 x 1.043 x 1.0 x 1.25 = 1193 AH
Section - 15:
When AH capacity required is larger than the nearest standard cell, the next larger size cell is required.
Section - 16:
Therefore AH capacity of the cell = 1200 AH
ISSUE
R3
FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-4
SHEET
31
OF 79
PART – A : LEAD ACID BATTERY
TYPICAL BATTERY ROOM LAYOUT
FOR DETAILS REFER HARDCOPY
ISSUE
R3
FORM NO. 120 R1
SECTION:
APPENDIX-4
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SHEET
DC SYSTEM
32
OF 79
PART – A : LEAD ACID BATTERY
Project :
Date :
Lowest Expected
Minimum
Electrolyte Temp : oC Cell Voltage :
Cell
Cell
Mfg. :
Type :
Sized By :
(1)
(2)
(3)
(4)
(5)
(6)
Period
Load
(Amperes)
Change in
Load
(Amperes)
Duration
of Period
(minutes)
Time to
End of
Section
(minutes)
Capacity
at T Min.
rate
K Factor
(KT)
(7)
Required Section Size or
(3)x(6B) = Rated AH
Pos Values
Neg.Value
LOAD DATA :
A1=
A3=
A5=
A,
A,
A,
M1=
M3=
M5=
Min;
Min;
Min;
A2 =
A4 =
A6 =
A,
A,
A,
M2 =
M4 =
M6 =
Min.
Min.
Min.
Section - 1: First Period only - If A2 is greater than A1, go to Section-2
1
A1=
A1-0=
M1=
T=M1=
Sec.-1
Section - 2: First Two Periods only - If A3 is greater than A2, go to Section-3
1
A1=
A1-0=
M1=
T=M1+M2=
2
A2=
A2-A1=
M2=
T=M2=
Sec.-2
Section - 3: First Three Periods only - If A4 is greater than A3, go to Section-4
1
A1=
A1-0=
M1=
T=M1+...+M3=
2
A2=
A2-A1=
M2=
T=M2+M3=
3
A3=
A3A2=
M3=
T=M3=
Sec.-3
Section - 4: First Four Periods only - If A5 is greater than A4 go to Section-5
1
A1=
A1-0=
M1=
T=M1+...+M4=
2
A2=
A2-A1=
M2=
T=M2+...+M4=
3
A3=
A3-A2=
M3=
T=M3+M4=
4
A4=
A4-A3=
M4=
T=M4=
Sec.-4
Total
***
***
Sub Total
Total
***
Sub Total
Total
***
Sub Total
Total
***
Sub Total
Total
***
Section - 5: First Five Periods only - If A6 is greater than A4 go to Section-6
1
A1=
A1-0=
M1=
T=M1+...+M5=
2
3
4
5
A2=
A3=
A4=
A5=
A2-A1=
A3-A2=
A4-A3=
A5-A4=
M2=
M3=
M4=
M5=
T=M2+...+M5=
T=M3+...+M5=
T=M4+M5=
T=M5=
Sec.-5
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
APPENDIX-4
SHEET
33
OF 79
PART – A : LEAD ACID BATTERY
Section - 6: IF LOAD CYCLE HAS MORE THAN 5 LOAD PERIODS, CONTINUE FURTHER IN SIMILAR MANNER.
Section - 7: Random Equipment Load only (if needed)
R
AR=
AR-0=
MR=
T=M+R=
Section - 8:
Maximum Section Size =
Section - 9:
Random Section Size =
Section - 10:
Temperature Correction Factor =
Section - 11:
Design margin =
Section - 12:
Aging Factor =
Section - 13:
Uncorrected size = (8) + (9)=
Section - 14:
All capacity required = (13) x (10) x (11) x (12)
Section - 15:
When AH capacity required is larger than the nearest standard cell, the next larger size cell is required.
Section - 16:
Therefore AH capacity of the cell = AH
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
FACING SHEET
SHEET
34
OF 79
PART – B : NICAD BATTERY
PART-B
NICAD BATTERY
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
DC SYSTEM
SECTION:
WRITEUP
SHEET
35
OF 79
PART – B : NICAD BATTERY
1.0
SCOPE
This section outlines the Ni-Cd alkaline station storage battery
performance characteristics, usage and sizing.
2.0
DIFFERENT TYPES OF Ni-Cd BATTERIES
2.1
The most common electrode design for the nickel-cadmium batteries
is the pocket plate type designated by 'P' as per IS:10918-1274. The
active constituents are cadmium in the negative plates and nickel in
the positive plates. The active material in each electrode is enclosed
in metal pockets of finely perforated steel strips. Each plate is
insulated from the next by thin plastic separators. The electrolyte is a
solution of potassium hydroxide in de-ionised water. The resulting
electrochemical reaction produces a nominal discharge voltage of 1.2
volts per cell. The electrolyte takes no part in these reactions and
acts only as an ion conductor. The other electrode designs are
sintered plate(s) and tubular plate(T).
2.2
The cells are further classified as H,M,L and X type based on the
discharge performance of individual designs. The plate type, and the
number of such plates employed in a cell indicate the cell type and
determine its discharge characteristics.
2.3
The cell container is usually translucent polypropelene
plastic.Polypropelene has high strength, it is corrosion free and not
electrically conductive. Cells can also be supplied in stainless steel
containers, if required, to with-stand conditions of high shock and
vibrations. Steel cells are mounted on wooden racks.
3.0
PERFORMANCE CHARACTERISTICS
3.1
The rated capacity C5 of any cell type is defined as available
amperehours (Ah) at 5 hours discharge rate at 27°C, to an end
voltage of 1.0V/Cell after charging for 8 hours with 0.2C5 A. (In the
U.S. the Ni-Cd capacity is based on 8 hours discharge).
The standard ambient temp. specified by IS:10918 is 27°C, whereas
the Ni-Cd batteries available in Indian market are rated at 20°C +5°C
ambient. The same is adopted in the design guide for the present.
3.2
Normal voltage is 1.2V/Cell
ISSUE
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TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SECTION:
WRITEUP
SHEET
DC SYSTEM
36
OF 79
PART – B : NICAD BATTERY
3.3
Open circuit voltage is 1.28 V/Cell.
3.4
The measure of performance is not the rated Ah capacity but the
battery cell construction. H type cells have thin plates (more plate
area per amount of active material) giving excellent high rate
performance. M and L types have medium thickness plates and thick
plates respectively. For example H-type cell at 15 minutes discharge
can deliver about twice the discharge current compared to an L-type
cell of equal rated capacity.
3.5
The published discharge data for nickel-cadmium cells are most
commonly available in tabular form, in which the current, available
from each cell type, is stated for a given discharge time and end of
discharge voltage. For intermediate times and voltages, it is
necessary to interpolate between the known values (IEEE 11151992).
3.6
There are three manufacturers in India, AMCO (in collaboration with
SAFT,France), SABNIFE POWER SYSTEMS LTD., Hyderabad in
collaboration with M/s Sabnife, Sweden and Punjab Power Packs Ltd.
in collaboration with M/s Alcad Ltd. UK. The available tabulated
discharge performance data from M/s SABNIFE on different types of
cells for varying end cell voltages, is enclosed at Appendix-1.(The
cell designations of Sabnife make cells confirm to IS.S10918-1274).
More details if required, may be obtained from the manufacturers.
3.7
EFFECT OF TEMPERATURE
Battery optimum performance is based on cell electrolyte temperature
maintained at 20°-25°C. For temperatures below 20°C a loss of about
0.5% of rated capacity per °C is expected for Ni-Cd battery. No
increase in capacity is to be considered above 20°C. The derating
curves enclosed in Appendix-1 can be used for arriving at the
derating factors appropriate to the lowest expected electrolyte
temperature for the individual installation.
Example:
Cell Type
Cell end Volt
Discharge time
Min. Ambient temperature
Lowest expected electrolyte temp.
: KPM100P
: 1.1 V
: 30 mins
: 0°C
: 0+10°C ( Ref. Clause 5.2.3
ISSUE
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FORM NO. 120 R1
TATA CONSULTING ENGINEERS
TCE.M6-EL-7186000
SECTION:
WRITEUP
SHEET
DC SYSTEM
37
OF 79
PART – B : NICAD BATTERY
of Part – A of this design guide )
: 0.925
Temp. derating factor
(From enclosed curves)
Available current at 10°C = 101A
(Data from performance table
at 20-25°C) x 0.925 = 93.425A
3.7.1
Life of the battery is shortened when temperatures are above the
reference temperature of 25°C. Generally it has been estimated that
Ni-Cd battery loses approximately 15% of its life for every 8°-10°C
electrolyte temperature above 25°C.
3.8
CHARGING REQUIREMENTS
To fully charge, a cell will require an Ah input, from the charger to the
battery, of 160% of the capacity. For example a 100Ah cell requires
160 Ah to fully charge it from a fully discharged state. If the charger
can supply 20A then the time for charging will be 160/20 i.e. 8 hours.
3.9
Cell Data :
Type-L
Type-M
Type-H
a) D C internal resistance,
ohms
0.20x(1/C5) 0.15x(1/C5) 0.06x(1/C5)
b) Maximum Short circuit
current, A
10xC5
15xC5
25xC5
3.10
The electrolyte specific gravity (S.G.) is not an indication of the state
of charge in Ni-Cd cells since it does not change appreciably during
charge or discharge. The acceptable limits to be maintained in normal
service (of the electrolyte S.G) are 1.17-1.19 at a reference
temperature of 20° at the specified level line of the cell.
3.11
Indian Standard 10918-1274 specifies the general requirements and
methods of test for Ni-Cd batteries. This is derived from IEC Pub 6231978.
4.0
APPLICATIONS OF Ni-Cd BATTERIES
Some typical applications of different battery (Cell) types (X,H,M,L)
are mentioned herewith for their optimum usage.
Applications of very high rates of discharge batteries (Type X) are to
deliver very large currents (>7C5) for very short durations (1 Sec-15
min).
4.1
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