Consolidation Coal Company

Design Innovations Inc.

Kevin D Dolinar

John F Burr

Barry R Lipsitz

Ruth M Lipsitz

Junction box

Bed sheet or similar article

A trolley wire for conveying direct current power to an electrically powered vehicle in an underground mine is connected in series with a shunt to a power source. The current drawn by the trolley wire passes through a circuit breaker and the shunt. The shunt generates a voltage input signal proportional to the current drawn by the trolley wire. A solid state comparator device receives the input signal and compares it to a reference signal having a magnitude representing the maximum level of current permitted to flow through the conductor. If the reference signal exceeds the input signal, the comparator device supplies an output signal that oscillates between a positive and a negative voltage to a trip circuit. The output signal actuates the operating coil of the circuit breaker so that the circuit breaker contacts remain closed to permit current to flow through the shunt to the trolley wire. Upon occurrence of an overcurrent, the input signal exceeds the reference signal and the comparator device responds by terminating the oscillating output signal to the trip circuit. Termination of the output signal deenergizes the circuit breaker operating coil. The circuit breaker contacts are then opened and current flow through the circuit breaker is terminated.

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Canonsburg, PA, United States of America

Kevin D Dolinar