ELECTRICAL PROTECTIVE DEVICE AND METHOD FOR SELECTIVE DISCONNECTION OF A SUBSYSTEM IN CASE OF A SECOND FAULT IN AN IT POWER SUPPLY SYSTEM

摘要

An electrical protective device (20) and method are for selective disconnection of a subsystem (6a, 6b) in the event of a second fault in an ungrounded power supply system (2) with a main system (4) and at least one subsystem (6a, 6b), the subsystem (6a, 6b) having a differential current measuring device (12a, 12b) and a switching device (14a, 14b) for separating the subsystem (6a, 6b).;The invention is based on generating and applying a measuring signal voltage (Um) between one or more phase(s) of the main system (4) or from a neutral point of the main system (4) against ground (9) using a resonant coupling circuit (22) that has a measuring signal generator (24) and a series resonant circuit (26) connected in series to the measuring signal generator (24), a resonant frequency (f0AK) of the series resonant circuit (26) being set to correspond to the measuring signal frequency.

主权项

1. An electrical protective device (20) for selective disconnection of a subsystem (6a, 6b) in the event of a second fault in an ungrounded power supply system (2) that consists of a main system (4) and at least one subsystem (6a, 6b), the subsystem (6a, 6b) having a differential current measuring device (12a, 12b) and a switching device (14a, 14b) for separating the subsystem (6a, 6b), comprising
a resonant coupling circuit (22) that is connected against ground (9) from one or more phase(s) of the main system (4) or from a neutral point of the main system (4) and has a measuring signal generator (24) for generating a measuring signal voltage (Um) that has a measuring signal frequency and a series resonant circuit (26) that is connected in series to the measuring signal generator (24) and has a capacitance (CAK), an inductivity (LAK) and an ohmic resistance (RAK).