Method and device for switching off an insulation-faulted part of an unearthed power supply system

摘要

The invention relates to a method and a device for switching off a system component provided with a connected equipment of an ungrounded power supply system in the event of an insulation fault in a DC circuit connected to the system part to be disconnected. The invention is based on first determining the insulation resistance of the IT power supply system and carrying out a measurement of the DC offset voltage present in the IT power supply system and then determining in a combined evaluation of the measurement results whether, due to the displacement occurring during the duration of a predeterminable time interval. DC voltage there is a risk of a disturbing influence on the operating behavior of the connected equipment. If a disturbing influence is to be expected, the immediate shutdown of parts with insulation faulty parts of the system takes place with the DC circuit and the equipment connected to it.