Answer / k.prakashchandra

Energy stored in a battery = AH x V watthour.Multiplying
with number of batteries you get total energy stored in watt
hour.Divide this by load in watt to get the backup time in
hours ,ignoring efficiency,losses and residual stored energy.

Answer / m.b.parthasarathy

The formula is as follows.

1. To find battery back up time : Battery AH X Battery volt X constant factor is divided by load(in watts). Perhaps if you have 100ah battery and the load is 500watts you can find back up time as follows.
EX: 1ooAH X 12V X 0.85 / 500
100AH X 10.2 / 500 = 2hrs.

2. To find battery AH : Back up time X load is divided by Battery volt X constant factor.Suppose you need 2hrs back up time with 500watts load, yu can calculate battery AH as follows.
EX: 2 X 500 / 12 X 0.85
1000 / 10.2
= 98.03AH. Commercially available 100AH battery only.

Answer / j.prakash

after the load and running time is decided the battery bank
size can be calculates the first calculation is to divide
the laod in watts by 10 for 12 v systems or 20 for a 24v
system ....

resulting in the number of amps required from the batter
bank..

AN Example of this calculation is:

1.total watts=1000watts.
2.amps from 12v battery =1000/10=100amps DC.

FOR A 12V BATTERY 100AMPS DC*3H=300AMPS HOURS(AH)

Sir,In our company there are 3 caterpillar make(capacity:(1) 3.3KV,2.5MW(2)3.3KV,2.5MW & (3)3.3KV,1.9MW) & 1 deutz make (capacity:11KV,3.8MW)gas engines utilised,all are running in paralell. There are three transformer utilised,(1) 6.25MVA,3.3KV/22KV,Impedence voltage:6.7% used for two generator,both are 2.5MW(2)5.5MVA,3.3KV/22KV,Impedence voltage:7.2% used for one generator of 2.5MW & (3) 5.5MVA,11KV/22KV,Impedence voltage:7.8% used for one generator of 2.5MW.all generator breakers capacity of 1250Amps. Sir,I want the details of fault level calculation of generator,transformer individually & for whole system. If you require any information from me.feel free for contact me sir.pl.send the answer of my question as the earliest as possible.

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