Date: Tue, 9 Aug 2016 17:22:45 +0100 From: Arthur Chance <freebsd@qeng-ho.org> To: RW <rwmaillists@googlemail.com>, freebsd-questions@freebsd.org Subject: Re: Power consumption tuning Message-ID: <8fd8eccc-aef7-eeaa-9851-b8ed03a6bfd8@qeng-ho.org> In-Reply-To: <20160809165640.5aa087c2@gumby.homeunix.com> References: <20160809172345.312117ac@e733> <fa791a431671032e9f0f47a7f8807957@mail.zplay.eu> <20160809165640.5aa087c2@gumby.homeunix.com>
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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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