Correcting Lead Power Factor

put an inductor in series with the load .

Do you have capacitors connected to your system?

yeah. they are automatic capacitor banks. is it worth to keep the pf at or very near unity? does these automatic capacitor bank have inductors inside them?

If the power factor is leading, then there is too much capacitance in circuit.

Check the operation of the automatic functions against the Operation & Maintenance Manual and contact the manufacturer if a malfunction is suspected. With this unit working correctly, there would then be no need for an inductor in parallel with the load.

Power factor correction units rarely have inductors in them.

As PWSlack stated there is too much capacitance in the load if you have a leading PF. If your capacitor banks are operating properly they should only be adding enough capacitance to balance the lagging inductance of your system. Either they are adding too much because perhaps each bank has a certain rating so when your load's PF drops,the bank or banks that cut in to balance the lagging PF are over correcting. I doubt that they would over correct to an excessive amount so you're probably OK. Like the other contributor asked, just how high a leading PF are you getting?

The power supply circuit consists of server racks (switches) ONLY, which I think induces leading power factor and not lagging power factor as my environment is a Tier3 data center. Therefore, I even suspect that the automatic capacitor bank is not even working or supplying reactive power! Is there anyone who can confirm my suspicion?

If my suspicion is true, how can I improve the power factor in the datacenter? I have learned lagging pf improvement but NEVER learned about leading power factor improvement

Help pls, thanks to those who replied and those going to reply (in advance)

Regards,

Versalite

Generally speaking if you have any induction motors that you are operating elsewhere, run some off this circuit since induction motors operate with lagging power factors this will help correct your leading power factor. Leading power factors are unusual since most plants have numerous induction motors operating. Just type of plant are you operating or what is the main part of your load comprised of? Is it mostly lighting or computers or what?

data center (tier3) with about 200-250 computers. standby generator. office lightings.

basically data center plus office stuff.

anyway, thanks to all the guys for sharing your experience and expertise. really appreciate it!

Certainly the Auto power factor correction is not working properly. The capacitors used are of not desirable value. Please get calibrated again according to your load.

A K Billore

Hi A K Billore,

I suspect that the pf correction design is flawed as it is more suited for industries with induction motors running, which supplying VARs to correct the pf.

However, in my environment, the circuit provides power for mostly servers (data center) and computers, which I believe their switching behaviour causes leading pf. Thus, how can I improve this leading pf in my datacenter?

Regards,

Versalite

Hi Versalite,

Certainly the auto P.F. Correction is not suiting to your datacentre load.In P.F. correction system there is no reactive component, only cpacitors are added or redused accordind to requirement.Also P.F.near to unity is never desirable. Hence it is advisible to check the P.F. without correction system. After that correction VAR may be calculated if at all required. Existing system of correction may also be verified by manipulation of different arrays by competent person.

A K Billore

Hi A K Billore,

Yes I agree with you that checking of the p.f. (not from the pf correction device) is needed.

However, lets assume that I've checked the pf without the correction system, and the p.f is leading in nature, how can I correct it successfully?

Thank you for your help thus far!

Regards,

Versalite

You have a leading PF. Check with the utility if you are being penalized for this. It is likely that you are not. Utilities like free KVARS. If not, Determine what the PF is. If its just a little leading its not a problem. Do what PW is saying. The unit should correct this problem.

Generally leading power factor is caused due to over compensation of inductive loads. It is higly reccomended that for selection of correct sizes of capacitor banks a thorough study of electrical load characteristic is required by deployment of proper electrical instruments, collecing and analysing the data. Power factor improvement upto 0.98 lagging is most suitable. The more the number of stage facility in PFC( Power Factor Controller) relay contain, fine control of power factor is possible provided, adequate protection is adopted for frequent ON/OFF of capacitor banks.

Leading power factor is also very harmful to various electrical equipments like transformers,generators etc., even it may damage the electrical equipments for prolong use. Therefore, please study your electrical power distribution networks, actual requirement of capacitor bank ratings, number of stage contol requires, may fix up power factor improvement upto 0.98 lagging to avoid this type of undesirable situations.

Manindra