Shutdown control means for an electric power supply.

摘要

There is described control means for shutting down a constant current supply (21) suitable to a double-end power feeding system for a long-haul wire telecommunication system. The sutdown control means comprises a voltage detecting circuit (26), a current detecting circuit (25) and an AND gate (27). The voltage and current detecting circuits (26, 25) provide the respective detecting signals when the constant current supply (21) provides an output voltage larger than a predetermined voltage value and the current at the output voltage is smaller a predetermined current value. The predetermined voltage and current values are determined corresponding to a input resistance of a load circuit to which the feeding of a current by the constant current supply (21) is stopped. Thus, the shutdown condition of the constant current supply (21) can be determined free from the drooping characteristic of the constant current supply (21) and hence the withstand voltages required for the circuit components and the assemblage thereof for the constant current supply (21) and the electronic equipment fed by the current supply (21) can be reduced. There are also described embodiments in which the basic concept of the invention is applied to constant voltage supplies connected in parallel to each other to a load circuit.