VM-3P75CT gives odd/wrong current readings below 2A

[Luc]

Hi @Dunnp, it’s the same explanation as @wjmb links to. Added below for completeness.

Incorrect Current Reading in the Grid Box of VRM

At near zero real power, the power factor also tends to go to zero. It’s hard to say where the reactive power is going without hooking up an oscilloscope, but I expect it to be caused in large part by distortion current. Aka current that isn’t part of the fundamental frequency. There is still some merit in the current displayed in the box as your wires do have to be able to carry that current. In an extreme case you may not be consuming or produce any real power, but you might still overload yo…

In addition, the “flip-flopping” between -2A and 2A isn’t actually a difference of 4A current flow. The VM-3P75CT reports the RMS value of the current, which by definition is always positive. We made the choice to report the current with the same sign as the power flow. So in this case, at +1W it reports 2A while at -1W it reports -2A, even though the actual RMS current hasn’t changed at all.