DG Set Basics

pranayshah; single phase divide kva by voltage will give you amps. for 3 phase divide by 1.73, divide by volts perry

this is the basics

Kva=V×i×cosΦ

Where v=Volts,i=Corrent in amphs and cosΦ(power factor)=0.8 for generators single phase

For three phase it is √3 V×i×cosΦ (0.8 power factor)for generators

CRM

Dear CRM,

The formulae given by you for single phase and three phases are for the out put of DG Set in KW and not for out put in KVA

V.Ambarani

what will be for kva base dg set.

if my dg is 25 kva , 3 phase.

Then as per 25000=400* Amp

Amp =62.5

which i think is misleading.

Most DGs are rated at 0.8 power factor. In 415 V, 3 Phase, 50 Hz standard countries like India, the rated per phase DG / Source current is = (KW)/(415*0.8*1.732). For your information, usually the DG vendors insist on loading of DG to maximum 85% of the rated current capacity.

Regards,

Sanjeev

as per ISO for declaration of rating and power the engine is designed to operate with a power factor 0.8 engine world wide are manufactured as per ISO if you try to improve power factor to say Unity or 1 your engine will be over loaded and may trip or call for frequent overhauls and replacement of engine earlier then defined by engine manufacturer hence every engine manufacturer publishes in print the rating of the engine at Power factor 0.8

CRM

power factor improvement above 0.8 should not be a problem as long as the total active power rating of the load falls within the rated active power rating of the DG.

rgds

Sanjeev