Integrity monitor for neutral-to-ground suppression circuit

Abstract

This invention relates generally to surge suppression and more particularly, to monitoring the integrity of a neutral-to-ground suppression circuit or other suppression circuit. In accordance with the present invention, a neutral-to-ground fault monitor is disclosed, eliminating one or more disadvantages associated with the prior art. One embodiment of the fault monitor includes a suppression circuit and a monitoring circuit where the suppression circuit includes a first terminal, a second terminal, a surge suppressor, and a current fuse, wherein the surge suppressor and the current fuse are operatively connected between the first terminal and the second terminal and where the monitoring circuit indicates a fault upon sensing a loss of functionality of the surge suppressor or the current fuse. Regardless of the cause of failure (e.g., transient or continuous, or positive or negative overvoltage or excessive current) or the type of system (e.g., DC, single or multi-phase AC), the disclosed invention reliably indicates a neutral-to-ground fault caused by any one monitored component. Whether the failure sensed is a surge suppressor or a current fuse, the monitoring circuit provides one or more alternative current paths to sense particular failures and further provides a failure indication for each detected failure. A light emitting diode (LED) circuit enabled by the monitoring circuit provides a reliable visual indication of a functional and a failed surge suppression circuit.