Abstract: A circuit interrupter is secured to a mounting pan together with an insulative block in turn mounting a transverse array of fuse load terminals in individual, spaced alignment with associated interrupter load terminals. A differential current transformer is mounted to the pan with its window located in the space between the interrupter and fuse load terminals. Plural fuses extend through the transformer window with their opposed end terminals in respective electrical connection with associated interrupter and fuse load terminals, whereby the transformer monitors the vectorial sum of the phase currents flowing through the fuses.

Abstract: Separate current transformers sense the individual currents flowing in each conductor of a distribution circuit. A full wave rectifying network includes a plurality of parallel pairs of like poled, series diodes connected between a pair of buses. One corresponding side of each transformer secondary is connected to the junction between a different diode pair. A series circuit consisting of an additional pair of like poled diodes and a burden resistor is also connected between the buses. The corresponding other sides of the transformer secondaries are connected in common to the junction between the additional diode pair. A voltage is developed across the burden resistor only upon the existence of an imbalance in the currents flowing in the distribution circuit.

Abstract: Various embodiments of a ground fault protection system are disclosed for protecting a multiple source distribution network consisting of at least two sources having their neutral points interconnected by main neutral and tie neutral bus and also typically by separate ground connections. The system operates to selectively trip a ground fault circuit interrupter by distinguishing between normal neutral loading regardless of the routes taken by neutral currents in returning to the sources and a ground fault regardless of the routes taken by ground fault currents in returning to the source feeding the fault.