chrisb at jesmond.demon.co.uk
Wed Apr 29 10:53:30 BST 2009
On Wed, Apr 29, 2009 at 10:05:01AM +0100, Michael Lush wrote:
> A frend of mine has a Power Owl
> You clip the sensor round the mains power were it comes in to the
> electricity meter. I guess you could clip it round the server power
> I'd be inclined to calibrate it against a inline power meter before use...
I have a similar meter from Efergy at home and once spent a frustrating
weekend trying to get it to agree with the official meter.
Eventually I realised that these meters are measuring VA, not W. The same
for resistive loads, but considerably different for inductive loads such
as CFL and electric motors. I have one "32W" CFL that draws 67VA.
Of course VA maybe what you want.
I got a few inline power meters from Maplins when they were on
offer at 9.99 http://www.maplin.co.uk/Module.aspx?ModuleNo=38343
(But they're now 22.99!) Ah, the current "deal" is
http://www.maplin.co.uk/Module.aspx?ModuleNo=223573 @ 7.99. OK for
domestic use but that doesn't really help in a rack or if you can't
unplug the server.
There must be a market for better power monitoring: I'd like a meter
that piggy-backs in the circuit-breaker socket of a distribution board so
that I can monitor each circuit. Individual devices would be even better!
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