A New Pilot-Less Continuous, Ground Wire Resistance Monitoring System for Electrical Power Supplies in Underground Coal Mines

The concept of continuous ground wire monitoring is nothing new and there are quite a few of such monitors available for continuous monitoring of ground wires in underground coal mine electrical supplies. However, as far as the authors are aware, a pilot-less true ground wire resistance monitor is yet to be developed since the existing pilot-less monitors either check the continuity of ground wires or show their change of effective impedance and not their true resistance. In this paper, the authors discuss the development of a new pilot-less continuous ground wire resistance monitoring system using sampling technique. The scheme developed can register small changes in the ground wire resistance and actuate an alarm or trip circuit of a circuit breaker. The new pilot-less ground wire resistance monitor developed gave a highly satisfactory performance and it was found to be intrinsically safe. The new monitor is expected to be an welcome addition to the familyof existing ground wire monitors.