Patent ID: 6967487
Filing Date: 2005-11-22
Classification: G01R,G06F,H02J

Abstract:
1. A fault test method for use in a system comprising one or more system units, wherein each system unit comprises at least two isolation devices and is powered by a plurality of redundant power supplies, each isolation device requires a forward biasing voltage at least equal to a respective forward bias voltage value to be operable in a normal conductive state and is electrically connected with a respective one of said power supplies such that each power supply has associated with it a set of one or more isolation devices, and an output of each isolation device is connected to a common load of the corresponding system unit, the method being performed by a testing system and comprising: selecting as a subject for a test procedure, the set of isolation devices associated with a corresponding one of said power supplies; controlling the power supplies during the test procedure to marginally vary an output voltage of at least one power supply such that a differential voltage is applied between an output of the power supply associated with the selected set of isolation devices and outputs of the remaining power supplies for selectively changing the conductive state of at least one isolation device by reducing the forward voltage thereof to less than said respective forward bias voltage; measuring the current through each isolation device in said selected set of isolation devices; and determining whether each measured current is consistent with the existence of a fault condition in the respective isolation device.