Power consumption tuning

Arthur Chance freebsd at qeng-ho.org
Tue Aug 9 16:22:54 UTC 2016

On 09/08/2016 16:56, RW via freebsd-questions wrote:
> On Tue, 09 Aug 2016 17:03:36 +0200
> Solène Rapenne wrote:
>> Buying a device to measure the power consumption is also a good idea,
>> so you can check your changes.
>> It costs around 12€. Example
>> http://www.ecvv.com/product/1000019919.html
> A lot of those cheap power meters will work with simple loads like
> heaters or fridges,  but are very inaccurate with computers. I have one
> and I've heard a lot of bad reports about them.

Clip-on type meters you get for measuring mostly whole house consumption
don't handle reactive loads (basically anything with a motor) well and
measure high. All the plug in ones I've tried work well enough, 1-2%
variation between units on realistic loads, near enough to the readings
of the industrial grade load monitoring I have on all my power circuits
at home(*), but they can fail in time if mistreated. They also can be
not very good with harmonic power but modern switch mode power supplies
are supposed to keep that to a minimum.

(*) Long story short: my wife's an energy consultant, advises both
government and industry and helps energy conservation charities, and if
it measures electrical power we've either got or tested at least one,
often more.

Schrödinger's cat had 18 half lives.

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