Patent ID: 7633733

Claim:
A power supply module adapted to provide DC power over a connected network that carries digital communications, the power supply module comprising: a conditioned DC power supply block adapted to limit coupling of a communications signal from a connected network into the conditioned DC power supply block, an output of the conditioned DC power supply block coupled to an output terminal of the power supply module, the output terminal adapted to connect to a network cable of a network, the output of the conditioned DC power supply block adapted for connection to a network cable of a network through the output terminal; an oscillator circuit coupled between the output of the conditioned DC power supply block and the output terminal, the oscillator circuit coupled to the output terminal so that the oscillator circuit is capable of conductively connecting to a network cable connected to the output terminal, the oscillator circuit having changed operating characteristics when a network cable connected to the output terminal has a cable short circuit; a detector coupled to the oscillator circuit to detect a change in the operating characteristics of the oscillator circuit responsive to a cable short circuit in a network cable connected to the output terminal and to output a detector signal responsive to the change in the operating characteristics of the oscillator circuit; and a switch coupled to the detector and to the conditioned DC power supply block, the switch connected in series between the conditioned DC power supply block and the output terminal, the switch suspending current flow from the conditioned DC power supply block to the output terminal in response to the detector signal and thereby preventing supplying current to a network cable connected to the output terminal at least while such a network cable has a cable short circuit.