Good morning,
Recently we came across one single phase 8KVAR (6KW) Quattro inverter with a single phase 2.2KW water pump attached at 300 metres distance from the inverter.
The pump pulls nominal about 8-9.5A at 230V (pending pressure) but during start 38-40A, 4 times its nominal power and the inverter gives an overload warning very short.
After checking the power factor, we discovered it to be only cos phi 0.2 inductive, very low indeed due to the long cabling as well of course.
We will install a basic Power Factor control device instead of a soft starter or power factor controller as it only occurs with this pump.
The relay is for 3 Phase, but we will just connect the Neutral (1st main contact) and Phase (2nd main contact) to the inputs and the outputs to the capacitor, the 3th main contact (we take the resisters off) and the 4th main contact are used to switch the motor starter relay.
The little block on the relay is also a relay what closes about 5-10 milliseconds faster then the main relay below it, the wires you see are resistor wires and will pre charge the capacitor before the main relay closes and so preventing big currents and sparks.
When the main relay closes the capacitor is charged and now the motor will start with power factor cos phi 0.9-1 inductive, now the motor will only pull about 2-2.5 times its nominal current and starts due to that very fast without the inverter giving an overload warning.
After it is started the power factor will be about cos phi 0.85-0.95 capacitive, but that is also good.
With such a device, for about 50-75 euro the issue is solved, instead soft starters or power factor controllers which are quite expensive and must be programmed which is not for everybody.
Please let us know what your experiences are with power factor improvements
With the very best regards, Jeroen.