Short circuit protection for AF power line carrier control - has relay which de-energises contactor short circuiting resonant shunt

摘要

The protection is for a resonant shunt connected to the powerline carrier control sender, which is a relatively low resistance load for the input transformer. This shunt is connected to at least one network used for this control. The resonant shunt, which can be short-circuited by a de-energised contactor, consists of compensation capacitors, power capacitors and series connected inductors. Measurement transformers (MW) are inserted into at least two connections (L) between the input transformers (EW) and the resonant shutn (RSH). When overcurrents occur in the connection (L), they energise a current dependent high speed tripping relay (AR) which breaks the contactor (SCH) cuurent.