A circuit arrangement for safe disconnection of an installation, in particular a machine installation

The invention relates to a circuit arrangement (90) for the safe shutdown of an installation (22), in particular a machine installation. Said circuit arrangement comprises a signalling device (14) which generates an output signal (46a, 46b) that is defined in accordance with the operating condition of the installation (22) and a safety switchgear (92) which, in accordance with the defined output signal (46a, 46b), shuts down the installation (22) in a fail-safe manner. The defined output signal (46a, 46b) has a signal value which remains static over a period of time during the operation (22) of the installation. According to the invention, the safety switchgear (92) has a clock pulse generator (30) for generating a clock pulse signal and has an input stage (16) with modulates the output signal (46a, 46b) of the signalling device (14), using the clock pulse signal.