| 摘要 |
A secondary ground fault protection for a high voltage power supply has a high voltage transformer with a center tapped secondary coil. The primary coil of a monitoring transformer is connected to the secondary coil at the center tap, which is approximately the midpoint of the secondary coil. The power supply load is connected across the end terminals of the secondary coil. The monitoring transformer is connected between the center tap and an earth ground on the primary coil side and between sensing circuitry and a digital ground on the secondary side. The sensing circuitry includes sub-circuits to generate various outputs which indicate the presence of faults, including a floating ground, excessive fault current or an open sensor transformer. The circuit outputs can be combined using a logical OR gate to cause specific actions in response to each detected fault, including terminating the high voltage generation in response to an excessive fault current. The fault detection circuit includes binary inputs for indicating what load is being powered by the power supply so that the ground fault sensing is more accurate and effective.
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