Abstract: A circuit for detecting the occurrence of a shorted diode in the rotating rectifier of a brushless alternator. A sensing circuit is responsive to the direction of current flow through the exciter field winding. A reversal of the current indicates that there is a shorted rectifier diode.

Abstract: A circuit for detecting the occurrence of a shorted diode in the rotating rectifier of a brushless alternator. A comparator has connected to it signals representing the base drive to the voltage regulator output transistor and the voltage at the terminal of the generator field winding connected with the collector-emitter circuit of the output transistor. The occurrence of a field winding terminal voltage of the order of the voltage at the anode of the diode which shunts the voltage regulator output transistor, in the absence of a drive signal to the transistor, indicates that there is a shorted rectifier diode.

Abstract: This invention relates to a shorted diode protection system for a brushless alternating current generator of the type having an energizeable exciter field winding. The system includes a circuit arrangement for sensing the voltage difference across the exciter field and pairing the voltage difference with generator load current to thereby provide an output signal that falls within a predictable range of values over a normal generator load current range. The output signal is of such a nature that it falls within a higher range of values upon the occurrence of a shorted diode. Another circuit arrangement is responsive to the output signal such that whenever the output signal exceeds a preset value over the normal load current range, an output is generated that operates to cause the interruption of the exciter field.