Abstract: The invention relates to a differential current monitoring device for monitoring differential currents in power supply systems, having a first measuring current transformer and having a measuring circuit for determining the differential current and having a computing unit for evaluating the differential current and for generating a switch-off signal. The differential current monitoring device has a device for detecting arcs, the integration of which according to the invention can considerably reduce the technical effort needed to monitor the differential current in connection with the arc detection in comparison to a functionally and spatially separate arrangement of both protective measures.

Abstract: A device safely switches a photovoltaic system and has a circuit breaker with input terminals and output terminals. The circuit breaker is configured as a switching module that includes a module housing and a switch contact arranged inside the housing for isolating at least one current path between one of the input terminals and one of the output terminals. A modular current sensor is provided which is to be mounted on the module housing of the circuit breaker.