On 20/05/14 06:53, Ian Field wrote:


"Daniel" wrote in message
...
On 17/04/14 23:46, Uncle Peter wrote:
On Thu, 17 Apr 2014 13:50:32 +0100, Daniel
wrote:

On 17/04/14 10:07, 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.

When I last dealt with this, power generator companies "assumed" there
would be an average power factor and set up their generators to handle
that. Your individual house (or, probably, even a small factory) would
not cause much variation in that power factor, considering the
generators are probably supplying hundreds of thousands of homes at the
same time!!

That won't apply to switched mode power supplies clipping off the peaks
though.

Wouldn't cause a very big blip in the grander scheme of things.

And what SMPS clips off the peaks?? Usually they vary the switch on
point in the A.C. waveform.

Between each peak the reservoir cap sags a little, each peak tops it up
againd and passes a large blip of current doing so.

Yeap, but the transformer Secondary's peak voltage must exceed the
cap's voltage to then "top-up" the capacitor.

AFAIK, current regs require a PFC front end on any switcher over 50W.

Don't know!! The impression I got was that domestic mains supplies PF
varied reasonable as it was, due to domestic fridges, fluoro's, T.V.'s,
etc, switching on and off at different times, that the major power
suppliers did not worry about the domestic situation .... but in
industrial situations, yes, the major power suppliers could/would
require PF correction.

In the 80s there were hundreds of thousands of TVs with half wave
thyristor buck regulators - the generating companies weren't happy.

Daniel