Setup 3 phases derived VT issues

[daniweb]

I have 3 days energy calculation:
Official counter: 69
IoTaWatt: 66.5

As the official counter has a resolution of 1 Watt I should probably wait a bit more consumption where 2 Watts would not make to much influence on the calculation (and I do not want to stay in front of the counter to watch when the value changes )

In case, how would I have to compensate/calibrate? “Manipulate” the Voltage calibration?
Before to start this statistic I again calibrated the VT, this time I took the volt measured directly at L1-N, before I was measuring at the plug near the VT.

[overeasy]

@daniweb

As the official counter has a resolution of 1 Watt I should probably wait a bit more consumption where 2 Watts would not make to much influence on the calculation (and I do not want to stay in front of the counter to watch when the value changes )

So 3%. My expectation with derived reference is that 2% would be good. I agree that the sample time is still a little short. Waiting for the counter to change would only address half the resolution problem. The initial reading would need to be done the same way. But I don’t expect it to improve better than 2% with time, and it may drift farther off.

@daniweb

In case, how would I have to compensate/calibrate? “Manipulate” the Voltage calibration?
Before to start this statistic I again calibrated the VT, this time I took the volt measured directly at L1-N, before I was measuring at the plug near the VT.

Adjusting the voltage calibration up/down will increase/decrease the kWh used, but I’m not a big fan of that. It will also increase individual watt readings. We don’t really know if the IoTaWatt is low or the official counter is high, or both. If you want to calibrate your MAIN_L123_WATTS to correspond to the official counter, you can simply add an adjustment factor to the output:
(L1_MAIN +L2_MAIN+L3_MAIN)*1.028