Abstract:

This paper presents the results of researching, designing and manufacturing leakage current protection device for 660 V/1140 V ungrounded three-phase electrical networks. The outstanding features of the device are: ability to create wide deformation characteristic; automatically detect and grounded the leakage phase. Device test results show that relay operation time ​​for symmetrical and asymmetric leak resistors are 30 kΩ/60 kΩ per phase and 20 kΩ /50 kΩ for 660 V/1.140 V networks respectively. The total operating time of the device when single phase leaking through a 1 kΩ resistor not exceed 105 ms. The circuit automatically detects and accurately grounded the leakage phase through 100 Ω resistance, the total detection and grounded the leakage phase time does not exceed 110 ms. This research result can be applied in the design and manufacture of high-quality and reliable leakage current protection devices used in underground mines, replacing imported products.