on the production of the reporting signal 58 is delayed by a second time interval which is governed by the capacitance 62 fig5 again shows the time sequences for the safety switching device 40 in the form of a graph at the time t 0 the operating voltage u b of the safety switching device 40 is switched on virtually at the same time the make contacts 24 26 of the relays k 1 and k 2 pull in so that the supply voltage u v is applied to the machine 42 the reporting signal 58 in contrast does not assume its active state until the second time interval t 2 has elapsed which corresponds approximately to the time for charging up the capacitance 62 if the operating voltage u b is removed from the safety switching device 40 at the time t 2 the reporting signal 58 reverts virtually at the same time to its deactivated high impedance state however the make contacts 24 26 of the relays k 1 k 2 remain closed until the capacitances 44 46 have been discharged in consequence the machine 42 is not disconnected from its power supply u v until the time interval t 1 has elapsed the control.