Test device for circuit breakers having electronic trip units

Claim 1

An electrical system for power distribution with current conductors, comprising: a circuit interrupter connected to the current conductors and including an electronic trip unit having solid state components; a current sensor on at least one of the conductors and having leads extending to the solid state components; a source of power for the electronic trip unit; an electronic test unit for monitoring the trip unit characteristics and having first, second, and third circuits; the first circuit extending from one lead of the current sensor to a ground potential and including a first switch, a light-emitting diode, and a current limiting resistor; the second circuit extending from one lead of the current sensor to an input test signal conductor and including the first switch, a first resistance, a potentiometer, and a second switch, the first resistance setting the lower limit of adjustability of the potentiometer; the third circuit extending from the input test signal conductor to the ground potential and including the second switch, the potentiometer, a second resistance, and the second resistance setting the upper limit of adjustability of the potentiometer; whereby the test unit is internally powered by the source of power for the trip unit.