| 摘要 |
PURPOSE:To judge a troubled point with ground shortcircuit from the phase difference between the voltage and zero-phase current of each sub-station collected at a master station from sub-stations furnished on a power distribution line. CONSTITUTION:A plurality of sub-stations 7 are furnished on a power distribution line 2, and the voltage is measured by a voltage measuring device installed on the power distribution line 2, and the zero-phase current is measured by a zero-phase current measuring device mounted alike on the line 2. The phase difference between the voltage and zero-phase current is measured by a phase difference measuring device 13 into which the obtained voltage and zero-phase current are entered. A master station 3 collects the phase difference from the first communication device 8 of each sub-station 7 via a transmission path 4 by the second communication device 10. Assume that a ground shortcircuit has occurred in a certain division, a ground shortcircuit current flows in this division, so that the substation situated on the side nearer the power supply than this division has a largely different phase difference from the sub-station situated on the load side. Accordingly the division with largely different phase difference is judged as with a ground shortcircuiting by the master station. Thus a ground shortcircuit sensing device can be structured cheaply because there is no need to provide sub-station with any zero-phase voltage measuring device. |
