Abstract: The invention relates to a method for operating a power source, wherein in a first operating state a current supplied by the power source via a power supply line is fed to a consumer and wherein in a second operating state a feed of a current supplied by the power source via a power supply line to the consumer is interrupted by a separator. a separator associated with the power source sends an identifier via the power supply line to a control unit associated with the consumer, when the power source supplies current. The first operating state is executed when the control unit returns an expected signal within a predefined time interval (td) via the power supply line and the second operating state is executed when another signal or no signal is returned within a predefined time interval (td) via the power supply line.