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Posted By: rhpope How to Measure Power Factor - 08/15/06 12:00 PM
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 as I am told this is really what you are looking for and trying to reduce?

Thanks,
Roger
Posted By: John Crighton Re: How to Measure Power Factor - 08/15/06 05:28 PM
I assume you're asking about a meter for small appliances that plug into 120 V receptacles. Fortunately, there's a really neat meter for the purpose, and it's less than $25.

Froogle "kill-a-watt" -- you can't miss it.

It's a digital meter that measures RMS voltage and current, frequency, power, power factor, and VA, and it's become an indispensable part of my tool kit.
Posted By: derater Re: How to Measure Power Factor - 08/15/06 06:49 PM
Hey, John what model do you have, do they vary in options/ performance? Froogle? I thought you were kidding!!
Posted By: John Crighton Re: How to Measure Power Factor - 08/15/06 08:04 PM
I'm pretty sure there's only one model, the P4400. Here's the manufacturer's web page for it.

They make great gifts for gadget geeks!
Posted By: Dnkldorf Re: How to Measure Power Factor - 08/15/06 08:27 PM
Roger,

What exactly are you looking to measure, or is your question in general about PF?
Posted By: rhpope Re: How to Measure Power Factor - 08/16/06 10:57 AM
The power factor question is related to a Rotary Phase Converter. I am trying to reduce the converters power consumption to the least possible amount. I just wanted to know how to measure the power draw from the two single phase legs on the input side so that is necessary I can add capacitance between these two legs to get the power factor closer to 0.9. Everything that I have been read is that a Rotary Phase Converter produces a bad power factor.

Roger
Posted By: renosteinke Re: How to Measure Power Factor - 08/16/06 02:14 PM
First of all...the "Kill-a-watt" is sold in the ECN store!

Power factor, simply put, is the difference between "watts" and "kva."

If you have a steady load, you can get a good idea by comparing the meter reading to whay you get when you measure volts, measure amps, and multiply the result. This is one of those times you want to have "true RMS' type meters!
Posted By: Dnkldorf Re: How to Measure Power Factor - 08/16/06 02:50 PM
Roger, count me in on this one. I want to see you get through it, and learn with you if you don't mind.


Give us the motor size and readings, and we can walk you through it, and all learn something together.

Radar??
Posted By: Almost Fried Re: How to Measure Power Factor - 09/12/06 05:40 PM
rhpope, what did you ever do about this concern?
Posted By: Trumpy Re: How to Measure Power Factor - 09/14/06 04:56 PM
Reno is quite right here.
Power factor is the ratio of useful power(VxI) to useless (Wattless) power in a circuit or even an entire installation.
To a degree, the lower the wattless component, the higher the power factor.
It is about using the most from what you have supplied to you.
We had a dedicated PF meter at the PoCo, but I can't at this moment remember how it was wired.
What's even more scary, is the fact that I built the thing in the first place. [Linked Image]
Posted By: ghost307 Re: How to Measure Power Factor - 09/15/06 12:55 PM
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).]
Posted By: ShockMe77 Re: How to Measure Power Factor - 09/18/06 10:00 PM
interesting thread
Posted By: Almost Fried Re: How to Measure Power Factor - 09/19/06 02:11 PM
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).]
Posted By: tajoch Re: How to Measure Power Factor - 09/19/06 11:24 PM
--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.
Posted By: Helectric Re: How to Measure Power Factor - 09/20/06 01:14 AM
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.
Posted By: rhpope Re: How to Measure Power Factor - 09/20/06 11:28 AM
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
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