How to calculate Generator Sizing?

Calculation for Generator sizing


The generator sizing is done based on the following conditions.

a) Load Calculate from continuous.

b) 10 % spare capacity for future loads.

A) Calculation of total load:

Total connected load as per load summary given below.

(Refer to generator sizing-load-summary details )

Continuous Load

Total KW  237.22
Total KVAR  0.00
Total KVA 279.08

Minimum KW =237.22 KW

Maximum KVA =279.08

B) Calculation for Generator Capacity 

Generator Capacity (In KVA) =Maximum Load X 1.1 = 306.99 KVA

(Considering 10% spare capacity for future loads)

So we select standard Emergency Generator rating of (KVA rated) =350 KVA



Rating = 350 KVA, 415V

415 volts 3 phase & Neutral, 50 HZ, 1500 rpm, PF -0.8, Solidity earthed

Note:– Rating Selected may change in case of substantial load variation.