[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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