A switchgear unit switches high DC voltages, particularly for interrupting of direct current between a direct current source and an electrical device. The switchgear unit contains two connections which project from a housing and which are electrically conductively coupled by a conductor path, a contact system which is arranged between the first and second connections and an isolating apparatus that can be tripped by a thermal fuse. The thermal fuse contains a melting location which is arranged in the conductor path and which is connected first to the contact system and second via a moving conductor section to the first connection. The isolating apparatus is tripped and the connection between the conductor section and the contact system is broken at the melting location when an arc produced when the contact system is opened has caused the melting temperature of the melting location to be reached or exceeded.