Power consumption tuning

[Arthur Chance]

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.