Sundstrand Corporation

Kenneth C Kramer

Roy S Baker

A protection circuit for a bridge rectifier having a plurality of ac inputs coupled to a plurality of line voltages, and a dc output, comprises monitoring circuits coupled to the line voltages for monitoring the line voltages and generating sequential line-to-line voltage signals, conduction circuits coupled to the monitoring circuits for conducting that portion of each of the sequential line-to-line voltage signals having a given polarity, the conducting circuits generating sequential half wave voltage signals having a given polarity magnitude, and discriminating circuits coupled to the conducting circuits for discriminating a faulted rectifier by monitoring the given polarity magnitude of each of the sequential half wave voltage signals. The discriminating circuits generate a protection signal in response to one of the magnitudes of the sequential half wave voltages signals being less than a threshold.

Detection and isolation circuit for a failed bridge power rectifier and

A system of protection which utilizes a simple circuit for the detection and isolation of single and multiple phase to phase and phase to neutral faults between a multi-phase source of electrical energy and a power conversion device driven therefrom. The circuit comprises a current transformer positioned at the neutral aspect of each phase winding of the multi-phase source of electrical energy. These current transformers sense the current generated by the source of electrical energy and produce a signal of proportional magnitude thereby. These proportional sense signals from each of the individual current transformers are transmitted to a controller which vectorially adds these signals to produce a single summed output signal. The controller monitors the percent ripple content of the summed output signal and generates an output protection signal if the percent ripple content of the monitored summed output signal exceeds a predetermined threshold value for a predetermined time interval. Means are provided responsive to the output protection signal for de-energizing the multi-phase source of electrical energy.

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Rockford, IL, United States of America

Kenneth C Kramer