3 Phase Metering Question (Kvarh)

[ProDave]

So I installed a 3 phase electricity meter for s customer today. All working fine, but I have a question.

There are two red lights.

One says 1000 imp per KWh

Other says 1000 imp per KVArh

Now I understand the difference between KW and KVA

But the KWh light is flashing roughly 12 flashes, for every flash of the KVArh light.

Now you might expect a difference between KW and KVA, but not that much.

So what exactly does KVArh mean?  What's the r for in there?

 

[ProDave]

Thanks for that explanation.

That'll be all them fluorescent lights then causing the less than unity PF.

 

[Steve3948]

And the purpose of it flashing is ?

Is it of any help or hindrance. 

 

[Technician]

But the KWh light is flashing roughly 12 flashes, for every flash of the KVArh light.

Question is;  might it be possible to do a ROUGH approximation

of the power factor from this.

 

[Manator]

If the pf is very low it will cost more!! some suppliers charge penalties. I would see if you can get a reading of the var and calculate the pf. If it is really low you could fit pf correctors.

 

[apprentice87]

Hi all,

I do not know for certain, but i think in the UK they only charge for the power consumed in kW, and disregard kVA, so you can waste as much as you want with a poor power factor, and it does not matter! well, at least as far as the size of your bill is concerned. For commercial supplies this might be different though. I know both my supplies [single and three phase] are with western power and they do not seem to care

If the thing flashes 12-1 would this not be like a power factor of .91  Dunno, not much good at maths!!!!!

My meter, the DNO one, it can read kVArh too, but i have never bothered to look what the reading is, not even sure if it is set up to "add it up" as it were.

john..

 

[Steve3948]

I agree with above, domestic they don't care, however commercial and industrial they do charge more and have a penalty.

Currently working on large house, L1 = House with Electric Aga, L2 = Air Source Heat-pump 1, L3 = Air Source Heat-pump 2.

Balanced in winter, well out in summer.

 

[Sidewinder]

John,

WPD don't care about PFC, as they no longer have anything to do with electricity supply or metering, they now only operate the distribution network, they can't even fit meters any more!

However, some energy suppliers also do not care about PF especially round here.

In some of the larger inner city areas then there may well be penalties for non-unity PF.

 

[Manator]

+ 1 with Canoeboy, I had a client a few years ago running a heavy machine shop, I reduced his bills by far more than I charged him for fitting PFC.

He was so pleased that I had sorted it out for him and could not believe his maintenance electricians did not know about it. :facepalm:  

 

[ProDave]

The meters I fitted are "private"

My customer owns a large industrial unit that he lets out as small units, his "business centre"  For most of his small units, the owner pays the electricity and the rent the clients pay is inclusive of electricity and heating.

One client is moving in to a whole wing of the building, but wants to be metered and charged for the electricity they use (they expect to be using a lot). So the meters I fitted are for the landlord to read and bill his tenant.

I don't think power factor is an issue here. The DNO's meter is still the old mechanical rotating disk type.

 

[apprentice87]

Hi Paul,

Yes forgot about that, i get the electricity from swalec. Not sure if they charge for low power factor, do not think so though, cannot really, as the meter is not set up to record it. I will just go and have a look now, see what it says!!

Back again! I pressed the little buttons but when i get to the kVArh bit it just shows all zeros....

Swalec must not charge then....

john..

A few years ago i used to work for a chap that seemed to know what he was talking about, he was an ex RAF radar engineer at any rate. Anyway, he used to maintain that if you fitted enough PF correction capacitors your meter would go backwards..

Cannot see it myself, i just think you would draw more current and the thing would just start speeding up again..

john...

 

[Technician]

If the thing flashes 12-1 would this not be like a power factor of .91  Dunno, not much good at maths!!!!!

Looking at this and doing a bit of basic trig the power factor

is well in excess of 0.95.