When using a variable frequency inverter (VFD), never use an earth leakage circuit breaker (ELCB or RCCB). This is a key point for the use of VFD.
Some customers choose the corresponding RCCB for the inverter when using the inverter. The result is: when the inverter starts, the RCCB will act, and the system cannot run at all.
Why?
The principle of the RCCB is that the zero sequence current is zero. When the inverter is used, the zero sequence current cannot be zero.
The wave on output side of the inverter is PWM wave, there is a capacitance effect of a long cable between the motor cable and the ground. When a shielded cable is used, the capacitance effect is more obvious.
When the inverter is working, the capacitor is charging and discharging, and current flows into the ground through the capacitor, and then flows back to the inverter from the grounding wire on the incoming side to form a current loop.
If a RCCB is used on the input side, it will act and cut off the operation of the system.
Therefore, do not equip your inverter with a leakage protector. If you want to ensure safety, just ensure the correct grounding of the equipment.
