Technical Information

Calculating kVA & kW (Three Phase)

Formulae
Volts (V) = Voltage generated
Amps (I) = Amps available
P.F. Power factor of load (Usually 0.8)
v3 = 1.732

Formulae	kVA = V x I x √3
	1000

Example 1

A 415 volt, 3 phase generator gives 200 Amp. Calculate the kW and kVA of the generator.

kW	= V x I x P.F. x √3	15 x 200 x 0.8 x 1.732	= 115 kW
	1000	1000
kVA	= kW	115	= 143 kVA
	P.F.	0.8

Example 2

What is the current available from a 150kVA generator at 415 Volts?

kW	= V x I x √3	Therefore I = kVA x 1000	= 208 Amps
	1000	V x √3

Example 3

If a customer requires a three phase current of 150 amps @ 440 volt, what size generator does he need?

kW	= V x I x √3	440 x 150 x 1.732	=114kW
	1000	1000

Note:- The calculations for kVA and kW current are the same at 50Hz or 60Hz.

Technical Info