Answer / thowsif_emerson_csm team

UPS Battery Cacl:-


BATTERY RATING CALCULATION:-

The formula employed rating calculation is as stipulated
below :-

FORMULA EMPLOYED :

DC Current X Duration in Hrs
Capacity of Battery ( AH )=%age capacity utilization

UPS(KVA) x 1000 x Load Power Factor (=1)

Where , DC Current=Inverter efficiency x End Voltage

Hence , VAH = AH x Nominal Voltage

For e.g. : for 3 KVA UPS , 1 hour Backup :
3 x 1000 x 1
DC Current= 17.0 A
0.93 x 10.5 x 18
17.0 x 1.0
Battery ”AH “ = 27.4 AH
0.62
Hence , 18 nos of 12V/28AH batteries will suffice .

TOTAL VAH = 18 x 12 x 28 = 6048 VAH

The following assumptions have been made in the above
calculations :-

1. DC Voltage – 216 for 3 KVA
2. End cell voltage / battery of 10.5 V
3. Load Power Factor = 1.0
4. Inverter efficiency = 93%

% Capacity utilization is :

Duration % Capacity utilization

½ hr (30 mins) 52%
1hrs 62%
2hrs 74%
3hrs 83%
4hr 85%

For ups and invertor battery selection chart lOG On to:-

http://www.sharanapower.com/selection2.htm

Answer / madhu sharma

9

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