Re: Electricity meter monitoring

["David Gumbrell" <david.gumbrell@xxxxxxxxx>]

Low cost energy meters like the Electrisave have no means of
monitoring the
voltage and therefore must make an assumption about the power factor in
estimating the power. Since we don't know the assumption we don't know the
(in)accuracy. The Electrisave is likely to over-read if power factor is
low.

I had been assuming that there were not too many non-resistive loads in my
house, but my strawpoll seems to indicate this may be wrong, especially if
you have many CFLs instead of nice resistive filament bulbs, even if they
have some power factor correction (another downside to CFLs you don't hear
about from the ban the bulb lot).

You may not care about power factor (and Electrisaves under reading) since
you are metered in Watts (real power), but since the electricity utility
has
to transmit the additional reactive power and suffer the transmission
losses, ie overrate plant and generate more power, you are indirectly
paying
for it. If you are trying to green your house this would also matter. And
if
you are also wondering where the high reading on your whole house power
meter is coming despite having turned most things off from you may also
care.

Cheers

David


On 24/01/2008, Vargster <vargster@xxxxxxx> wrote:
>
>   Okay.... but this means what in practice?
>
> That when my Electri-save meter says I'm using 800watts, but I have
three
> PC's on, it's not really 800 watts, more like 1000 watts?
>
> Lee
>
> On Jan 23, 2008 11:23 PM, Chris Hunter
<cjhunter@xxxxxxx<cjhunter%40dircon.co.uk>>
> wrote:
>
> > http://en.wikipedia.org/wiki/Power_factor
> >
> > Chris
> >
>


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