Wednesday, October 19, 2011

Power Factor Capacitors

In today's economy, we all should be doing what we can to conserve and watch every dollar that goes out.  One simple way to make sure we are not paying money that we shouldn't is to make sure you are not being charged for a "Power Factor Adjustment" on your power bill. 

Whether you know it or not, you are contractually bound to be at .90 or better on you Power Factor.  What that basically means is that your electrical equipment needs to be running at 90% efficent or better or the power company is going to charge you a penalty for the difference of where you are and where you should be.

It used to be easy to just look at a facility and see what the load is on a typical day.  From there, we would size a capacitor bank or two in order to get the Power Factor above the .90 range.  In today's world we can't do that due to non-linear loads and other variables that may not exist well on the same system with the capacitors, which brings me to my next topic....

Over the years, many of you have purchased capacitors from us or others.  Changes in your facility since the installation of the capacitors is likely to have happened such as:

Adding a few Variable Frequency Drives, Solid State Starters or ?

Has this happened?  If so, your capacitors are probably no longer in service.  The fuses are blown or the capacitors are just shot.

You can easily check a capacitor with a ammeter on a 480 volt system by multiplying the kVAR by 1.2 and measuring the amps on the caps.  It should be whatever the number is from the above.  If not, they are out of service.  This is a "Power On" test and should be only done by someone trained to do this and they must be doing it in accordance within all the existing safety rules that may apply to this type of activity.

Really in today's environment, a power study of the facility is in order if you are need of Power Factor Correction.  If you have existing capacitors and they are not working, make sure you determine what caused them to fail prior to having them repaired and put back into service.  This is a must if changes have been made to you system.

If you need help with you power bill in determining whether you are paying for the adjustment or not, just send it to me and I will take a look at it for you.

Hope this helps,

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