[mythtv-users] OT: Standard LVDC power (was: HDHomeRun Prime iPad app)
Simon Hobson
linux at thehobsons.co.uk
Mon Aug 22 08:13:50 UTC 2011
Jay Ashworth wrote:
> > Let me guess, you have high neutral currents ?
>
>Well, probably, but it's more that the power company gets pissed at you
>because your meters read low.
Actually the power meters read correctly. The standard meters measure
real power not volts * amps. With a poor power factor then there are
volts and amps, but not as many watts - the power companies don't
like this as it means they have to provision cables to supply the
amps, without getting the cash in from supplying as many watts.
The fact that they are moaning means that you aren't big enough to
justify charging* you for VARs (Volt-Amps reactive) which also almost
certainly means you aren't big enough to actually cause any
significant problems.
Also, considering that (at least in the EU, dunno about elsewhere)
there are now considerable restrictions that mean anything but the
very smallest PSUs now have to have a half-decent power factor and
waveform. Thus even adding up 500 power supplies, they should not add
up to a huge problem.
* Large industrial users often have dual meters - one measures real
power, the other measures reactive power. They also often have a
third meter which measures peak load as well and pay for that since
it's peak load that is the limiting factor in the whole system.
> > Actually, they aren't hard to design or make - just hard to design &
> > make **very very cheaply** - ie for a halfpenny or whatever most
> > vendors want to pay.
>
>I'll buy that. But not for much.
:)
--
Simon Hobson
Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
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