I would like to measure consumers with the WEM3080T that are on different phases. However, each phase has its own differential circuit breaker, so I cannot connect different phases to the device and a single neutral, or the differential breakers get triggered.
I tried to naively connect all three inputs and neutral to a single phase, and the split core on the line connected to a different phase picks up some power: will I get an inaccurate reading by doing this?
I see two other alternatives:
- Buy a 3 phases + Neutral differential + over-current breaker just for the device (an extra single-phase Iammeter would be cheaper ;)
- Connect the Iammeter directly on the phases with an over-current breaker but no differential breaker (this doesn't seem very safe/legal, I live in France)
This wiring can not work correctly.
You power all Ua, Ub, and Uc to the same phase now,it is wrong.
You need to power the Ua by the voltage of phase A.
power the Ub by the voltage of phase B.
power the Uc by the voltage of phase C.
Because there is a 120 degree phase angle difference between each phase in 3 phase system.
the active power reading= U*I*power factor
Power factor=cos(phase angle difference between the U and I )
(U and I must belong to the same phase)
If you power the Ub by the voltage of phase A and still clamp the CTb in the wire of phase B.
The power reading of phase B will be calculated totally wrong.
Because the angle it used is not the phase angle difference between Ub and Ib but the phase angle difference between Ua and Ib.