Abstract: A power distribution system for supplying power to a plurality of point-to-load power supplies includes a plurality of bulk power supplies, each having a separate respective power distribution bus coupled at the output thereof. Each power distribution bus is coupled to each point-of-load power supply through an OR gate such that if one or more of the bulk power supplies fails, or if a fault occurs on one or more of the power distribution buses, then the point-of-load power supplies are unaffected because they continue to receive power from the other bulk power supplies via the respective OR gates. Furthermore, if a power distribution bus becomes short-circuited to ground, the current therein is limited electronically by the respective bulk power supply. Hence, the power distribution buses are protected against overcurrent without the need for a multitude of dc circuit breakers.

Abstract: In a dc-to-dc converter, alternating current or pulsating direct current produced by a cyclically switched power supply passes through semiconductor rectifiers or diodes. The rectifiers may be subject to unwanted conduction characteristics attributable to charge storage, which may result in cyclical current spikes during normal operation. A current sensor is coupled to sense a current which includes the cyclical spikes. A controllable attenuator or gain element couples the sensed current in a feedback loop to shut down the converter in the event of an overcurrent. To reduce the possibility of shut-down due to the normal cyclical current spikes, the attenuator or gain element is cyclically switched so as to reduce the sensitivity to the current spikes when they occur.