Good news for a change

(Brian Drury) #1

I thought it would be good to share the solution I adopted for calibrating my recently purchased EmpnPi. After a fair bit of faffing about I managed to get the system working but the live power figures were reading about 10% high. I looked at the AC mains figure and that was also 10% high compared to my fluke DMM so I inserted a resistive divider to allow the measured AC to be adjusted to equal the DMM and now everything is spot on.

Happy bunny now.

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(Robert Wall) #2

You could have altered the “scales = …” values in emonhub.conf to achieve the same result.

(Brian Drury) #3

Excellent! thank you Robert, I shall give that a go.

(Brian Drury) #4

Changed from 0.01 to 0.0095. Now much more accurate, thank you.

(Robert Wall) #5

Bear in mind that the maths to calculate power is done a long time before the data reaches emonHub, so you must apply the same scaling to the powers as well as the voltage.

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