On Thu, 03 Jun 2010 13:27:51 +0100, wrote:
On 3 Jun,
wrote:

Is there any cheap/easy way to measure the power consumption of mains
powered equipment that consumes a few tens of watts and is almst
certainly non-sinusoidal? In particular I want to measure the power
consumption of a (hopefully) low power PC that should be consuming
around 25 watts.

What spec is that? my atom board one with one hard drive takes about 40
watts. I wouldn't expect much less other than for a netbook.


A cheap plug-in power meter (a Brennendal one) claims it's consuming
about 50 watts but I'm not at all convinced it's telling me the truth.

The Aldi/lidl ones I have seem quite accurate, but at low (10w) levels the
resolution is poor.

You could always increase the power consumption to get it into the meter's
linear range. For example, get some 60W bulbs (3 or 4) in parallel. Connect
them up to the meter and measure the power consumption. Plug in the load from
your low power device as well as the bulbs and see how much _extra_
consumption is taken.


I know 'proper' power meters are expensive and I don't really want to
spend lots of money, nor do I really want a very accurate answer. If
I can just confirm it's consuming something between 20 and 30 watts
I'll be happy.

Can one buy kwh meters relatively cheaply? I'm quite happy to wire
one up to a plug and socket and use that over several hours to see
what's being consumed.

I compared my cheap ones with one and found them accurate. You should be
able to pick a proper mechanical KWH meter for less than £20.