Over-current protective apparatus for a power circuit

An overload relay which may be programmed for use with alternating current motors having different full load current and service factor ratings, said relay comprising:

• a generally rectangular housing having a front end, a rear end and side and end walls extending between the front and the rear ends to provide the housing with a closed interior, a pair of supports extending rearwardly of the rear wall providing means for mounting the relay on a panel so the rear end is spaced from the panel, at least one bore extending through the interior between openings in the side walls, circuit means within the interior responsive to the magnitude of alternating current in a conductor extending through the bore and connected between an alternating current source and an alternating current motor, said front end having three terminals thereon for connecting the circuit means across one phase of the source and in series with a coil of an electromagnetic switch that has switching contacts arranged to interrupt the current in the conductor when the coil is de-energized, an opening exposing a light emitting diode which is included in the circuit means and energized when the relay responds to excess current in the conductor to visually indicate that the circuit to the coil is de-energized and the relay is in a tripped state, a reset switch having an operator extending externally of the front end for causing the coil circuit to be energized and the diode to be de-energized to indicate that the circuit means is reset when the switch operator is actuated a predetermined time interval after the circuit means has responded to an excess current in the conductor and the circuit means is programmed to operate in a manual reset mode, a plurality of switches having operators accessible from the front end, a first of said switches having contacts connected in the circuit means to cause the circuit to operate in a manual-reset or automatic-reset mode, a second of said switches having contacts arranged to program the circuit means so the relay may be used with two different motors having different service factor ratings, a third of said switches having contacts arranged to cause the circuit means to trip independently of the magnitude of current in the conductor to test the operation of the circuit means said plurality of switches also including a group of switches each arranged to program the circuit means response to a preselected increment of current flow through the conductor.