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Re: [TCLUG:22753] Measuring power consumption (was MP3 player)
why not just use an inductive curent meter?
Thank You,
Ben Kochie (ben@nerp.net)
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"Unix is user friendly, Its just picky about its friends."
On Tue, 17 Oct 2000, Bill Layer wrote:
> The multimeter will do just fine but you will have to play one trick or
> another to make the necessary series connection with the power cord to
> measure current draw.. I have a special, short extension cord that has one
> conductor broken so that the meter may be inserted in series with the loop.
>
> Set the meter for the current scale and measure the current draw with the
> device powered on. Then, keeping the device powered on, set the meter for
> an AC RMS voltage scale and measure the supply voltage at the wall - it's
> not wise to estimate, as AC mains voltages can be anywhere between 109 and
> 126VAC - with 117 being nominal. Once you know current and RMS supply
> voltage, power (wattage) calculation is this easy:
>
> P = E * I (Where P is power (in watts), E is energy (in volts) and I is
> current (in amperes))
>
> I should mention that most all (even inexpensive) meters automatically give
> AC voltage readings in RMS - so don't get too concerned about this issue.
> If the meter doesn't say otherwise, it's giving the reading in RMS.
>
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