Method for operating battery charger for supplying electric power to electromotor of e.g. electric car, involves decoupling charging device from power supply system if difference value between currents exceeds predetermined threshold value

摘要

The method involves coupling a charging device (13) with a power supply system (16) by conductors and a neutral conductor. Current transferred through the conductors, and another current transferred through the neutral conductor is detected, where the conductors conduct three-phase alternating current (AC). Current difference value between the currents is determined, and the charging device is decoupled from the power supply system if the current difference value between the currents exceeds a predetermined current threshold value, where the value lies within a range of 5-40 milliampere. The power supply system provides a single-phase AC voltage of 230V or a three-phase AC voltage of about 400V. An independent claim is also included for a charging device for charging an electrical energy storage unit of a vehicle.