power factor reducer/power saver plug - do they work?

fatlad1971

Incisor wrote: »

You can upload what you like. Meters take account of power factor in their various ways.

Domestic meters account for it entirely and factor it in completely to the reading [they integrate the product of current, voltage and power factor over the meter reading period [or from the moment of leaving the factory, but that's another story]] to give a kWh [energy] reading. So power factor would not show up on a domestic bill, but it certainly exists in the domestic situation.

Industrial meters integrate the product of current, voltage and power factor to produce a kWh [energy] reading in the same way as domestic meters, but over 3 phases. They also integrate the product of current and voltage over 30 minute periods without power factor and record the peak half hour integrated product of current and voltage to give a peak half hour KVA reading. This punishes industrial users for poor power factor on machinery. Again, power factor is not mentioned on the bill.

So, post your bills, power factor does not appear, but despite what you say, it does exist. You might as well post Magna Carta for all the good it will do you in proving that Power Factor does not exist.

My knowledge goes up to the meter , i admit beyond this point i am fairly ignorant

My job is procuring energy , which in reality is a mathematical exercise, Im not an electrical engineer

Like ive always stated " Power Factor Correction is not a concept that is used in measuring or metering electricity consumption "
and we have established by your last post this is correct

I have never called myself an expert , nor would I
Ive just said that i have been in the industry for over a decade and feel that i have something to give to the posters on this board

Incisor

tomstickland wrote: »

This is about getting information correct, not egos.

I've had a quick read up on the theory and can see roughly what it's about. ie: inductive and capacitive loads causing a phase difference between voltage and current. The result of a low power factor is that higher current is drawn for the same output power.

This is inconsistent though:

Only apparently inconsistent. Power factor correction will reduce the current, but reduce the phase angle of the current vector relative to the voltage vector, which is what you say.

The domestic meter accounts for power factor and charges for energy. Power factor correction makes no real difference to the energy consumption registered by the domestic meter. Is that what fatlad was trying to say? It's a far throw from saying power factor does not exist, which means you could cut about 6 months out of any electrical engineering course if it took symmetrical components with it.

Incisor

fatlad1971 wrote: »

My knowledge goes up to the meter , i admit beyond this point i am fairly ignorant

My job is procuring energy , which in reality is a mathematical exercise, Im not an electrical engineer

Like ive always stated " Power Factor Correction is not a concept that is used in measuring or metering electricity consumption "
and we have established by your last post this is correct

I have never called myself an expert , nor would I
Ive just said that i have been in the industry for over a decade and feel that i have something to give to the posters on this board

You actually said [post 3] "There is no such thing as power factor in electricity metering domestic or industrial". Well, sorry, it does.

And all we established with my last post is that domestic meters use the concept in order to give a true energy reading and industrial meters actually measure maximum half hour kVAh. Power factor is as central to electricity metering as voltage or current. Domestically it is factored out, Industrially, it is also factored out of 1 reading and fully taken into account in another.

tomstickland

Incisor wrote: »

Only apparently inconsistent. Power factor correction will reduce the current, but reduce the phase angle of the current vector relative to the voltage vector, which is what you say.

The domestic meter accounts for power factor and charges for energy. Power factor correction makes no real difference to the energy consumption registered by the domestic meter. Is that what fatlad was trying to say? It's a far throw from saying power factor does not exist, which means you could cut about 6 months out of any electrical engineering course if it took symmetrical components with it.

Oh, I see what you mean.
The meter is designed to fully "understand" power factor, but still produces the same output quanity as for simply integrating the instantaneous voltage x current quantity.

Is there any reason why the electricity companies don't charge for true kVA?

tomstickland

Incisor wrote: »

You actually said [post 3] "There is no such thing as power factor in electricity metering domestic or industrial". Well, sorry, it does.

He is correct in intention - the power factor is not relevant to domestic electricity metering. With industrial supplies it is monitored.

Incisor

tomstickland wrote: »

Oh, I see what you mean.
The meter is designed to fully "understand" power factor, but still produces the same output quanity as for simply integrating the instantaneous voltage x current quantity.

Bear in mind instantaneous means the moment by moment value up and down the waveform. It is the product of these values being integrated, so, strangely, this takes power factor into account. Oddly enough, I no longer desire to integrate [V sin(2 * pi * 50 * t) * I sin (2* pi * 50 * t + phi)], but if you do, out falls a factor, cos(phi), which is the power factor. BTW don't go thinking it is instantaneously integrating rms voltages eg: 230Volts * 13 Amps or whatever, it is by doing it up and down the waveform that cos(phi) is dealt with.

Is there any reason why the electricity companies don't charge for true kVA?

The cost of kVA is capital for the plant to allow it to flow, rather than coal being burnt and plant to carry it which is the case for kWh. Until recent years, most domestic load has been heating and lighting, which has excellent power factor, plus the metering gear is far more complex - but industrial concerns with mainly motors will require thicker cables and larger transformers to carry the kVA, to they are metered for this besides the kWh

tomstickland

Yes, I had a good think about it whilst I was doing something else and it all seemed very clear. All you have to do is measure peak voltage and current and the phase lag and you can work everything else out.

As the phase lag increases then the amplitude of the current also increases to keep the overall power integral constant.

In terms of plant design, it's the higher peak currents that demand larger wires etc.

Anyway, for domestic customres, it won't make any difference to their bill.

Regarding that integral, it's the sort of thing we'd do as 1st year engineering degree.

x = 2*pi*t*f
where t is time and f is frequency
define instantaneous voltage as
v'=v * sin(x)
instantaneous current
i'=i * sin(x+y)
where y is the phase lag


y =vi [ sin(x)*sin(x+y)]
y=vi [sin(x)*(sin(x)cos(y) + cos(x)*sin(y)) (Trigonmetric identity)
y=vi [sin(x)^2*cos(y) + sin(x)*cos(x)*sin(y) ]
y=vi [(1-cos(2x))*cos(y) + sin(x)*cos(x)*sin(y)] (Another trig identity)

integrate over x

y =vi* [ (x - (1/(2*pi*f)*1/2sin(2x))*cos(y) + 1/(2*pi*f)*sin2(x)/2*sin(y)] (Integration of second term by parts)
This integral is evaluated for one cycle (x=0 to x=2*pi).
The sin(x) terms come out as zero, leaving

y = vi*2*pi*cos(y)

I might be a factor of 2*pi out, but the structure is right, looks far more complicated on here than on paper.

1carminestocky

Incisor wrote: »

All the more reason to be hard on him.

Absolutely not! My contention is and has always been that there are posters posting stuff on here and NOT being truthful as to who they work for. It would appear for too long that this forum has existed as some sort of cosy discussion group/caretl for people who derive their livelyhhoods from the energy companies (plus from the related industries, mentioning no names :rolleyes: ) If the 'average' punter reading this forum is to be able to evaluate the info on here in the correct manner, then I believe it is wholly right that any industry 'insider' should make it clear that they derive their income from the energy industry. It's common sense, really...

SwanJon

1cs - we've been through this before, and to be honest the way you went about it has meant that some people (me included) make assumptions about your posts before they've read them but, if you look, there are posts when you offer advice and nothing else.
Mentioning your employer doesn't automatically make you truthful, and not mentioning it doesn't make you a liar. I'd agree with you that if you work for a company and pretend you don't that's bad, buit we'll never know.
If you want anyone involved in the energy industry to declare it, should all those who don't, and therefore cannot provide that insiders view declare that as well?
Along the lines of "I'm only guessing/regurgitating the tabloids/my mate down the pub said this so take what I say very cautiosly"? You wouildn't go to a baker for help with your car, but you might askk him where he takes his car.
I have no suspicions that anyone on here has tried to hide the fact that they work for a supplier - in fact many of them start off their early posts with it - they have come here to offer help and advice, they are unlikely to be head honchos, they cannot make a personal profit through this site. Yes some people may lean towards their own employer(deliberately or not - it's the company they know most about after all), but there's enough people here for a fairly balanced view (usually).
Repeated baiting or asking the same question in various threads just puts people off asking for or giving help.
As prices (of pretty much everything except houses) continue to rise many people will come here looking for ways to save money. Griping about the wway things are won't help them. Changing tariff or payment method might. Changing their habits or insualting their home might, but we need to work with the wayt the industry is now -part of a global network that we (the UK) no longer control the way controlled our own supplies 10 years ago.

1carminestocky

Whilst I totally accept most parts of your post, SW, how many time on here have you ever recommended people using a supplier other than BG? I'm not in any way suggesting you are 'dodgy' and I acknowledge that you have expertise with regard to energy issues but the fact remains you are in the employ of British Gas and have already admitted you can make commission on sales. That's why I genuinely believe it's in the interests of the 'other' people on here for them to see who you work for and who you derive your livelihood from. Don't you at least accept my point here? It's not OK IMO to point it out 'in your first post' either, what about people who join the debate on here at a later date? They wouldn't necessarily know who you are and who you work for..