POWER AND POWER FACTOR

It is common to use mechanical kW to indicate the engine power but for alternators there are two ways to indicate power:

kW (active power) and kVA (apparent power). The ration of these two is the Power factor

kW = kVA x P.F.

What does Power Factor mean?

In a DC circuit the power in Watts is a product of Voltage x Current.

In an AC circuit the Active power is not always the product of Voltage x Current.  It is related to the Power factor, which depends on the type of load (see Load Types):

 

The relationship is:   Watts (W) = Volts (U) x Amps (I) x P.F (single phase

                            Watts (W) = √3 x (U) x O P.F. (three phase)

                            P.F. = (CosФ) = Watts ?Volts x Amps

                            W ?A    

                    or      kW ?kVA