Power factor Correction

Hey CB,

If most of your load is from your lighting circuits, you may want to consider the age of the ballasts. If they are new electronic ballasts, you probably don't have much of a power factor issue.

If instead, they are the old klunky (technical term for big and heavy) cheap magnetic ballasts then there could be a slight improvement with the addition of a capacitor at the actual ballast. You might want to start by looking at the utility bill for your electrical consumption because your average power factor should be on it.

You can address the power factor on either side of the transformer but eventually the ballasts will be replaced and then you won't need PF correction. Some of the old magnetic ballasts included capacitors in their design. There is a good chance that you only have two makes (models/types) of ballasts to consider. Check it out and get back to us!

I consider the transformer is big enough as it is for the entire building . I want to inform u that if power factor is low that means more current will be flowing through all the cables , switches , main switches, transformers and this is going to continue upto the power generation source. Under stand that with low P.F. It will be overloading of equipments or underutilisation of equipment. It is important to note that overall power drawn is going to be same in any case.

The best way to correct P.F. is to attach capacitor with the light Or any other equipment which uses copper winding and produces magnet ( like electric motors , etc.)

After adding capacitors with the lamp u should put automatic P.F. controller on the output ot the stepdown transformer. YOU are also recomended to attach one capacitor of suitable value to the input of transformer ( this will take care of low P.F. due to transformer).

In case more details are required than mail me at narwal_sunil@yahoo.co.in

You can use a a portable load recorder to take measurements to size your power factor correction capacitor.

Just a few things to keep in mind:

Your load changes daily , seasonally. The automactically switched banks work good becuause they can switch in and out the correct amount of VARS as required without overcorrecting.

I would think you would want the PF Correction as close to the equipment that is causing the problem. You may want more than one bank.

I have monitored circuits with the Caps in and out of the circuit. Like you other guest notes, The KW does not change. Your kVA, and current draw decrease. It was kind of a waste for my client because he thought he was going to save $$ on his utility bill. It turned out the utility PF penalty was minimal.

Your statement is a little backwards. KVA is the apparent power (rating of the transformer). KW is the actual power consumed (true power consumption). Power factor is nothing more than the ratio of true power to apparent power or KW/KVA. EX... If you have a 30 KVA transformer and a wattmeter reading 24 KW of consumed power...you have a power factor of 24/30= .8 = 80% Power Factor

Hey HollaIFyaHEMI , what if he had a 100kVa transformer? Probably would make more sense if you had said "if you measure 30 kVa and 24 kW . . .otherwise a world full of trusting individuals on this site might get their math very confused based on transformer size and not measured values.

If the pf correction is done at the inlet of the transformer,

the line draws the optimim current , however within the transformer both the zero phase and the reactive current flows, losses increased.

If on the secondary side, the reactive is taken care of by the transformer and transformer losses are minimized but the line current will be including the transformer reactance.

The second case is likely to be much smaller., also putting capacitabnces in the secondary may be cheaper (lower voltage)