In the case of supply voltages (24 VDC) there may be a delayed rise in voltage at the activation moment of the entire system as a result of a short term peaks in the power supply units used. The modules of the type series PROTECT-SRB (Schmersal) and SRB (Elan) have circuitry which also compensates for a "slow" rise in voltage in order to avoid functional disturbances in the "Auto start" operating mode.