Capacitor Banks Setting - Lagging or Leading?

Simply put.....

(1) No, your plant (like virtually all plants) is made up of mostly inductive machines (load). Changing to a leading power factor would require a VAST quantity of power factor correction capacitors (acting as a capacitive LOAD) to overcome the existing inductive load (your plant equipment).

(2) See note (1), most controlled loads are inductive hence lagging PF.

(3) Lots of capacitors, costing lots of money. No actual advantages come to mind.

Who told you that it would be a good idea to do this anyway?

Hi Jack

Thanks for your feedback.

The statement came from an external certified competent personnel who came for an introduction visit last two months ago.

By the way, may I know what industry would use the LEADING PF side in their electrical power supply then?

He did mentioned that if we change to the LEADING side, we can save electrical power supply and also protects our machineries. Is this true?

Then, our contract electrical guy mentioned that the if we change to the LEADING side, the electrical power cables around the plant will heat up due to over current supply in the circuit. Is this also true?

Please advice. Thank you.

Well from what you have just said he doesn't sound very competent at ALL. He wasn't a capacitor bank salesperson was he?.

Leading PF is quite rare, some welders could have a leading PF, but I dont know of an installation that has an uncorrected leading PF.

Your kW will actually go UP due to losses in the additional capacitors in the capacitor bank, and you may have overvoltage issues. You may possibly save some money on your maximum demand charge however, perhaps this is what he meant. I don't know what he was talking about when he said it would save your machines. You will NOT however save enough (if any) to pay for the capacitors required to move to a leading PF.

Electrical power cables may heat up if you change to leading PF, but it would depend on the situation.

In conclusion, DON'T try to change to a leading PF. Stick with trying to correct the PF to a lagging value of around 0.96 or 0.97. Any higher and the cost verses benefit starts to drop sharply. Going to a leading PF the cost verses benefit analysis goes out the window along with a big sack of the companies money.

Hi Jack

I must admit I'm not a specialist in this area. Do you have any scientific tools so that I could use it to proof to my colleagues.

Once again thanks for informative information.

please send your email Id i will send some pdf notes related to this topics...

because no attachment is possible..

Hi Mahalingam

Sorry for not replying earlier, I was away from office. You could email me at the following email address bcp@ambu.com.

Many thanks in advance for your help.

First thing you should do is find out the power factor the utility company bills on. If it's only 90%, don't change anything. You won't get any payback and you'll make the capacitor bank work harder. It will therefore, die sooner. Why make it work harder than it has to? You might even increase voltage or harmonic levels by getting greedy. Egads!

If the utility bills at 95% or more, you can crank it up at no cost. The microprocessor is programmable either digitally or by turning a dial. Let me know what model you have and I'll help.