ECN Forum Forums General Topics of the Trade General Discussion Area How to Measure Power Factor

Check out this wikipedia entry...it's got good diagrams and a good explanation. In brief, multiplying Volts time Amps gives you "apparent power" in kVA.
http://en.wikipedia.org/wiki/Apparent_power

I get this type of issue all the time as an engineer when I get handed a catalog sheets with value for watts for a load like a big chiller and some %#&^ decides that is enough information for me to design a feeder.
Watts is the power that most folks know about; kVA is the only viable source of calculating the amperage actually needed to operate a load.
Dividing watts by volts works fine for heaters, toasters and other purely resistive loads, but most electrical loads have motors or other non-linear components that make things a bit trickier.

[This message has been edited by ghost307 (edited 09-15-2006).]

interesting thread

Roger
I recommend that you contact the mfg. of your particular converter and ask them how to proceed. I'll bet that the question has already been asked and technical studies performed. They exist to sell stuff and probably have every possible tech support angle covered so as to help you sell/service their products.

[This message has been edited by Almost Fried (edited 09-19-2006).]

--How do you measure power factor and what do you measure it with. Is there some type of hand held meter that can be used to measure watts--

We have a Power Pack at work, that we use to record all sorts of useful information, it will pretty much tell you everything that going on.... It was a lil Pricey tho.

Roger,

Just out of curiousity, can I ask why your trying to correct the phase converters power factor? Is it because you're being penalized by the POCO for low power factor or are you trying to free up system capacity?

Years ago we used a portable meter that was about the size of an old analog meggar to measure power factor. Now we use the multi-function ct. analyzers like the ones Dranetz or several other manufactureres make. These will also allow you to trend power factor on feeders etc.

You might ask your POCO if they will help you with this.

Sorry for not replying until know. I am looking into this because phase converters are notorious for have a power factor of about 0.2 so I was looking into a way to measure this easily to since the amperage draw with it idling is can be upwards of near the full load motor amps. So far, the easiest thing to do is add capacitance across the L1 & L2 and that has great reduced the Line amps. The high amps on the Lines reduces the available amps on the other side of the converter for the machinery to run on.

Thanks,
Roger