How to calculate Generator Sizing?

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.