On 18/04/14 10:44, Andrew Gabriel wrote:
In article ,
"Uncle Peter" writes:
On Thu, 17 Apr 2014 18:31:28 +0100, wrote:

On Thursday, 17 April 2014 01:07:25 UTC+1, Uncle Peter wrote:
Can someone confirm that power factor is NOT taken into consideration for domestic supplies? I have a feeling it isn't, but I can't find any information on the internet. If it matters, it's a modern (5 years old) electronic meter I have. The power factor in my house is an average of 0.7 so depending if it's charged for or not, my bill could be completely different.

That depends on what you think you mean by your first sentence.

Domestic meters work with true watts, not volt-amperes. AFAIR, they all explicitly indicate that they measure kWh. There is no charge for having a bad power factor; you can take as many amps as you want at no cost, providing that your current and voltage waveforms are orthogonal. Except in principle that the amps must not be more than the supply rating and in practice that the amps must not blow the fuse. And if they ever find that you are doing something intentionally unreasonable, they'll make sure that you suffer for it, somehow.

Thanks, that's the answer I was looking for. Although does that also apply when taking power off the peaks of the waveform for ****ty switch mode supplies?

Yes. They generate 3rd-harmonic distortion, which can be bad in large
quantities because it adds together in the neutral line, rather than
canceling out between phases.

If you have Economy 7 or Economy 10, and use that to control storage or immersion heaters, your power factor will improve while the heaters are active.

Nope, gas. Although I rarely use it.

The supplier will not care about your domestic power factor as such; it is the total reactive volt-amperes that you take which might concern them.

Your non-zero power factor is *most* unlikely to be compensated by opposing contributions from neighbours. But the actual supplier (the operator of the street wires and transformers) will know the likely overall power factor of a residential street, and can fit compensating reactances if beneficial enough.

Your single-phase supply will of course be an unbalanced load contribution for the street's three-phase supply; but your neighbours on different phases will on average restore the balance sufficiently.

Maybe not, I use a lot more power than most. Can phases cross over with substations? Or is each one seperate right back to the power station? What I mean is.... is there such a thing as a transformer which takes 3 phases in the primary, and gives three phases in the secondary, but you can draw more from one phase on the output and put more in on a different phase on the input?

The final step-down transformer is a delta-star configuration,

Not here it ain't. Nor any of the pole mounted transformers on the local
11KV overheads. One phase partial deltas.

Star-delta is not a configurations that exists in the real world either.
Its one or the other.

Its hard to see how you can supply a single phase from three phases
anyway. A single phase is always the result of the difference between
two phases.

You cant extract a single phase from a star connection anyway. A star
connected load implicitly is a three phase load.




as there
are no neutral conductors in the supply network until you step down to
240V. A high load on one of the 240V phases becomes a not so high load
on two of the three phases supplying the final stepdown transformer, so
you can see that your one-phase load is already being smoothed as you
work back up the supply chain.



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