Abstract: In a redundant power supply system, N+1 power supply modules are operated in parallel to provide power to a single load which may be connected via a DC bus and may employ a remote voltage sensing circuit. Each power supply module includes an ORing element that isolates a corresponding AC power supply from delivering power to the load in various conditions representing a fault occurring in the system. Each ORing element and power supply module is coupled to a control circuit that drives the operations of the ORing element. The control circuit includes three comparators and associated circuitry each for detecting one of the following conditions of system failure representing by: the presence of reverse current flowing across the ORing element caused by short circuit in the system, a selective overvoltage condition caused by a power supply delivering too much voltage to the load; and a failure in an AC power supply giving rise to an undervoltage condition.