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Sensing Power

Edson Brusque askes

You know how to calculate the RMS power based on a series of (above 0) samples from an AC input? I could simply note the peak value (say, 3V) and calculate it's RMS (3V * 0,7 = 2.1V, IIRC). But this assume the input is a perfect sine, and maybe it's no true.

Harold Hallikainen replies:

Square each sample as it comes in (resulting in a 16 bit number), add up 256 of the squared samples (24 bit result), divide by 256 (back to 16 bit), then take the square root (back to 8 bit).

Power@ Tools@ Current (Amps)

Note: Utility companys do NOT measure of the amount of energy delivered. They charge you as if all phases were delivering the same amount of power. If all your energy comes through one phase (because you have thing plugged into the breaker box in an unbalanced manner) then you will be billed the same as if ALL phases had that much power coming through them. Get an electrician to visit your house and ask them to check the balance of your phases and move circuits around accordingly.

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