The control power supply of the earth leakage detection circuit is taken from the inside of Earth Leakage Circuit Breaker. If used on the secondary side of the inverter, electronic part of earth leakage detection circuit may be burnout due to high frequency, therefore it is not possible to use. For earth leakage detecting devices on secondary side of an inverter, Earth Leakage Relays applicable to harmonics and surges (NV-ZLA and NV-ZHA) are recommended. However, the control power supply of Earth Leakage Relay shall be taken from the control power supply without harmonics.