Power Factor Meter

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jerjwillelec

jerjwillelec

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Nevada, IA
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Master Electrician
I've been asked to meter the power factor for someone...I've never done this before. Any suggestions on a decent power (factor) quality meter?
 
jerjwillelec said:
I've been asked to meter the power factor for someone...I've never done this before. Any suggestions on a decent power (factor) quality meter?
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Power factor metering and power quality metering are not synonomous. Be careful of your specifications.

Are you looking to rent or own this meter?
 
That's a good question. I am a very small business owner (2 employees including me) /electrical contractor...been in business for 6 1/2 years...and I am trying to grow some. As I said, I've been asked to measure the power factor but at this time don't have any details on what they are really wanting. He simply asked if I was interested...which of course I am but unfortunately don't know a lot about it...as I primarily have been involved in residential contruction...
 
Can you tell us why this guy wants his PF measured? What type of equipment? How accurately?
 
jerjwillelec said:
That's a good question. I am a very small business owner (2 employees including me) /electrical contractor...been in business for 6 1/2 years...and I am trying to grow some. As I said, I've been asked to measure the power factor but at this time don't have any details on what they are really wanting. He simply asked if I was interested...which of course I am but unfortunately don't know a lot about it...as I primarily have been involved in residential contruction...
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Whether power factor or power quality this is something you don't just jump into without some knowledge of what you are working with. First you need to know what they are concerned about before you know what you will need to monitor.
 
Joethemechanic said:
Can you tell us why this guy wants his PF measured? What type of equipment? How accurately?
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Hahahaha...you would think I knew this wouldn't you??? Unfortunately...I don't know much about it. All I know is it has something to do with wind turbines, and obviously capacitors. I think their POCO is telling them they're PF is too low and they want a second opinion???
 
kwired said:
Whether power factor or power quality this is something you don't just jump into without some knowledge of what you are working with. First you need to know what they are concerned about before you know what you will need to monitor.
Click to expand...

I am quickly finding this out...a little nervous but definately interested! Just don't know where to start...
 
Ok so I would think that this guy is going to want a report based on test equipment with up to date certifications and everything. You better talk to a test equipment rental co or just sub it out
 
jerjwillelec said:
I've been asked to meter the power factor for someone...I've never done this before. Any suggestions on a decent power (factor) quality meter?
Click to expand...
That's a tough question, as there are many things to consider. If you just want to check PF to a single 1 phase load I guess the cheapest way would be to buy an inexpensive watt meter (like an Extech or Amprobe, about $350) and just compare the VA to the watts and do the math. If you want to check, say, a service or 3 Phase load it gets a little more complicated as to be accurate you need to measure from all 3 phases at once and you are getting into a much more expensive meter which typically includes some level of PQ function. I happen to use an AEMC 3945 as it is fairly comprehensive, but the down side is it is about a $4000 meter.
 
jerjwillelec said:
Hahahaha...you would think I knew this wouldn't you??? Unfortunately...I don't know much about it. All I know is it has something to do with wind turbines, and obviously capacitors. I think their POCO is telling them they're PF is too low and they want a second opinion???
Click to expand...

If wind turbines are also backfeeding POCO there should not be power factor problem, you have power factor problems with inductive loads - primarily motors and magnetic lighting ballasts.

Bigger problem with co generation is to make sure you are in phase with the POCO.
 
kwired said:
If wind turbines are also backfeeding POCO there should not be power factor problem, you have power factor problems with inductive loads - primarily motors and magnetic lighting ballasts.

Bigger problem with co generation is to make sure you are in phase with the POCO.
Click to expand...

What if he is generating with induction generators, they need reactive power from the line or else a cap bank to function
 
Electrical Machines Drives And Power Systems by T. Wildi
 

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Joethemechanic said:
What if he is generating with induction generators, they need reactive power from the line or else a cap bank to function
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Could be exactly right.

I don't know but there is a textbook answer, wind turbines are commonly induction M-G's and need the utility for energization of the stator, voltage regulation, and VAR balancing. I would also guess VAR flow could swing widely with changing wind turbine output.

Very nice followup posting Joe, interesting. Thanks
 
Power factor is load dependent and changing. So an instantaneous reading or reading averaged for a portion of day won't convince the POCO. POCO have their own method of calculating power factor. It is the mean power factor. based on either kVAR-hours or kVA demand or kW-hrs & kVAR-hrs for the billing period. Though this method is flawed, but this is what they rely on. PF (COS?) is calculated using Pythagorean theorem for the power triangle. Adding a capacitor bank with automatic power factor controller may be the way to go, but after some study from an expert. Switching capacitors are not always tolerated in many cases. Also overcompensation has its own sets of problems.

power-triangle_inline.jpg
 
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