Phase Angle Meter (Power Factor Measurement)

[Brandon314159]

Anyone ever put one on their get set? Any come stock with?

A picture attached for consideration:

 

[Ken_86gt]

I have seen and used them on the military gens that are 750KW and up. I don't really see a need for one on the smaller gens because it probably isn't cost effective to correct the power factor at low loads.

 

[shovelheadmike]

Hmm... never thought about adding one. Would be interesting to know how out of phase my voltage and current load is. Of course, since I only have a 20 KW generator, every time the a/c starts it would probably peg it on the lagging side.

 

[Brandon314159]

I have a MEP-006 and run small power grids for events around the PDX area...might be a useful bit of information.

 

[cvh20]

These gens three phase?

 

[Brandon314159]

The subject applies to any generator really...

 

[cvh20]

If they are single phase, they won't register anything on the power factor meter.

 

[shovelheadmike]

If they are single phase, they won't register anything on the power factor meter.

How do you figure that? Any AC electrical circuit that is.not.100% resistance load will have a.power.factor. Which, is the phase angle.relationship.between the voltage and current. You can have a single phase or three phase device.

 

[surplusHQ]

Just to throw in my two cents..... when I was in the worlds greatest Navy, we used phase angle meters to parallel generators. If you try to close the generator breaker .5% or more out of phase, it will automatically open back up so you dont destroy your generators.

 

[Ken_86gt]

Exactly as Mike said- single or 3 phase has no relationship to power factor.

 

[Ken_86gt]

You don't use these power factor meters to sync generators. You use sync scopes or lights!

 

[cvh20]

Shovelmike, I hear ya and I agree. But the original poster was asking if they come stock on the generators or should he add one. For whatever reason on a civilian generator, you will almost never see power factor meter on a single phase generator, only a three phase generator. I think it is because you usually use two watt meters on different phases to calculate the power factor in real life, which you won't have on a single phase generator. It's not that you don't have a power factor, just not a power factor meter (that is economically feasible).

 

[Brandon314159]

Shovelmike, I hear ya and I agree. But the original poster was asking if they come stock on the generators or should he add one. For whatever reason on a civilian generator, you will almost never see power factor meter on a single phase generator, only a three phase generator. I think it is because you usually use two watt meters on different phases to calculate the power factor in real life, which you won't have on a single phase generator. It's not that you don't have a power factor, just not a power factor meter (that is economically feasible).

Sorry should'a mentioned dealing with bigger than the average generator

I have a meter already that I might throw in just for checking each phase for good match at heavy load.

 

[Bob USNR]

Just a note to surplusHQ.
On the ship I was stationed on the starter on one of the 4-71 diesel gens wouldn't work. The electricians considered closing the cross connect switch to see of the alternator would act like a starter... or not.
No one was sure if the gen would be destroyed... or not.
In the end no one was sure enough to try it.

e

 

[shovelheadmike]

IMHO, there is no benefit in knowing the powerfactor of any given load on a generator if you don't have any way to.correct it. Unless you have some capacitor banks you can switche on or off as needed, it is simply unless information. Not being rude,just trying to put it into perspective.

 

[shovelheadmike]

Unless you have means to charge for the power you are providing, rather than that which is actually being used. I.e. real power vs apparent power. In layman's terms: beer or foam... A a glass of each cost the same, which would.you prefer?

 

[ETN550]

IMHO, there is no benefit in knowing the powerfactor of any given load on a generator if you don't have any way to.correct it. Unless you have some capacitor banks you can switche on or off as needed, it is simply unless information. Not being rude,just trying to put it into perspective.

The small 3kw -10kw gen sets many on here have are rated to be at full rated load .8 PF at a load meter indication of 80%. And rated to be at full rated load 1.0 PF at a load meter indication of 100%. Since these small sets are often run at max load it is handy to know the PF in order to determine what load meter indication equals full load for the given PF. Or at what point the set is above rated max load. Since the sets will run continously at the rated load we do not pay much attention to anything if we are underloaded. If we get overloaded then we start considering the PF, actual ambient conditions, and time at the overload condition. just my 2 cents..

 

[Ken_86gt]

The most important thing to monitor is AMPS on all non prime power generators. The pf is just a way of seeing how far the current is lagging or leading the voltage. As long as your are operating within the rated amps of the generator- the pf means nothing when looking at capacity. Don't make this out to be something bigger than it is.

 

[shovelheadmike]

The most important thing to monitor is AMPS on all non prime power generators. The pf is just a way of seeing how far the current is lagging or leading the voltage. As long as your are operating within the rated amps of the generator- the pf means nothing when looking at capacity. Don't make this out to be something bigger than it is.

That is correct. All you should be concerned with is the amp.draw on your generator. The voltage may droop.a.little, but it is amps.that will trip your output breaker.

Unless you have a means to adjust your Powerfactor...

 

[shovelheadmike]

If you have a LARGE generator, those all have an adjustable field voltage. When you over excite your field, it creates capacitive reactance, which will.make your PF better. I.e. more beer.and less foam for any given horsepower.

Remember ELI the ICE man? Voltage leads current in a reactive circuit while current leads voltage in a capacitive.circuit. Capacitive reactance is used to combat the reactive losses created by all of those air conditioner compressors. This is where the terms leading and lagging Powerfactor come from.

I normally work on generators that are 180 MW and up. Not quite portable.