Reactive Power Compensation

Lyn,

Your EHP works well!!

(Extra Homework Perception)

Regards,
Sapper

That one was easy.

The value you have quoted is likely to be the optimal load PF which the generator will operate at . In order to evaluate the actual KVAR you need to look at the field excitation specfication.Field excitor will draw reactive power since it will create excitaion field needed to develop EMF in the stator . This value should be fairly constant if load PF is kept at 0.9. However it will change as the load current changes and PF swings.

Generators are designed to run at maximum efficiency under PF ranging from 0.85-0.9. This can be verified from the generator's data-sheet using the field exciation curves. As PF increases, generator's available power drops hence de-rating occurs. Same can be said if the PF drops. The most important aspect is maintaining the Pf of the connected load at the optimal level to get Maximum efficiency of the generator. If the generators is running in standby mode then it is important that existing PF correction equipment is dropped out of circuit until the generator has accelerated and voltage in regulation. I have experienced issues with generators due to leading PF thus causing generators not perform as expected. Harmonics as well is something you need to look at especially if loads are of electronic nature. Also you may o use PF caps the if the load has a poor PF,hence sizing of the PF will be load dependant rather than being related to the generator.

An easy approach will be to quote the rotor current from the data sheet then evaluate Q =I*V ,if exciataion current is Dc ,or sqrt(3) *V if exciation is via rectifier.

This will give u an estimate of the reactive power consumed by the gennerator.

Ideally you would not need PFC equipment unless your load is hungry for reactive power or the load draws excessive current during startup.