Automatic on=off switchgear for domestic main supply installation

摘要

The switchgear automatically switches off the mains voltage on disconnecting of the last consumer appliance in the controlled network and instead applies a not dangerous control voltage. The switch-on control voltage has a magnitude sufficient for connection of a current for a fluorescent tube and phase-controlled consumer appliance. In a series-connection arrangement a high resistor is in series with a d.c. voltage source. The d.c. voltage is pref. derived from a mains a.c. voltage via a diode. In a parallel-connection arrangement, some resistors serve as high-ohmic voltage source for the d.c. loop. A separate earthing systems may be used for the ON current and the OFF current. A time element may be provided for the OFF delay.