Safety emergency-off switching for contactor feeders with an upstream power circuit breaker

摘要

Conventional emergency-off devices for main circuits have until now been implemented by redundant design of the motor contactors. This is highly cost intensive, labour intensive and occupies a large amount of space, since the main current paths of the contactors in this case have to be connected in series. The present invention makes use of the fact that a power circuit breaker is connected upstream of the motor feeders in most cases. The undervoltage trip device of the power circuit breaker is thus used for emergency-off switching. To this end, the coils of the contactor feeder have timers connected in parallel with them, whose contacts (which open in a delayed manner in the event of a voltage failure) are connected upstream of the undervoltage trip device, with a normally-closed contact (break contact), which is connected in parallel therewith, of the associated contactor. Emergency-off switching in the case of distribution networks.