Abstract:

To ensure safe conditions of electric shock, protective relays apllied in the 1140V underground mine power supply system must have the automatic detection and earthed leakage phase functions. These relays should have fast response time; sensitivity and reliability in the case of detect the leakage phase. In this paper, authors propose an automatic detection and earthed leakage phase circuit diagram. The circuit operates based on difference between RMS value of leadphase voltage and combination of two lag-phases and zero sequence voltages. The Matlab Simulink and Electronic Workbench simulation results show that proposed circuit have high reliability for leakage phase detection; sesitivity no less than 18 k per phase; detection time for leakage phase less than 20 ms; total time for detection and earthed the leakage phase is not exceed 50ms.