Motor starter arrangement delays triggering of first switching device if overload occurs, opens second device in delay period, only opens first device if second fails to isolate connection

摘要

The motor starter arrangement delays triggering of a first switching device when overload occurs, opens a second switching device is opened via a communications arrangement within the delay period and opens the first device if second fails to isolate a connection. The arrangement has a first electrical switching device (2), especially a circuit breaker, with an electronic trigger unit (2a) for producing an overload trigger signal, a second electrical switching device (4), especially a relay, whereby the switches are in series to connect or isolate a load (M) of at least one phase and a current supply, a bi-directional communications arrangement (6) between the switching devices. Triggering of the first switching device is delayed when overload occurs, the second device is opened by the communications arrangement within the delay period and the first device opens if the second fails to isolate the connection.