Power Saving Calculations Through Power Factor Improvement

Hmmm... simple really.

kWh without PFC = kWh with PFC

Get it?

PFC devices benefit the power producer more, hence the added fees for poor power factor by the end user. Your equipment uses the same power as before, but devices with windings tend to run warmer producing more heat as a "waste" product, but operating exactly as designed. Improved PF may benefit the user by extending the life of their equipment.

Thanks a lot. Can I calculate it through reduction is I2R Losses due to PFI.

You can but it is not as simple as that.

You see the reactive current (or power) is the demand of the load, and that has to be met (say a motor runs at 0.85pf then it will draw the reactive current corresponding to this, no matter what.

What you can do is to put the pf compensator (PFC) so that the reactive power is supplied by the compensator and not from the source (ie power supply utility).

The reactive current now loops between the load and the pfc and the corresponding I2R loss will take place here, in addition to a bit of loss in the capacitors that you have added.

The saving will be in the I2R loss between the PFC and the say supply transformer. However these usually will have cables with sufficiently low resistance and thus the saving may not be worth the effort.

Same happens to the generators- which try to compensate (or supply) the reactive power by controlling its field excitation, thus increasing its field coil losses along with the increased I2R loss in the armature.

Again the saving will not be significant unless the pf is really low.

This matter has been discussed several times in CR4 with the net result- not worth it unless

a) pf is too low

b) There is a penalty on low pf

c) The loads are distributed over sufficiently long distances (thus having significant line losses) and the pfc is put in the vicinity of the loads (or at least local nodes, as is done in our factory)

I never heard it explained quite like that...

You will get a saving if you pay for power in KVA and not KW. A bigger saving if you are penalised for low PF.

Capacitors added will only increase - not decrease - although, slightly, the power consumption.