DETECTING METHOD OF PREDICTIVE GROUND FAULT ACCIDENT AND PREDICTIVE GROUND FAULT ACCIDENT SECTION OF HIGH-TENSION DISTRIBUTION LINE

摘要

PURPOSE:To prevent a serious accident from occurring by determining that a distribution line wherein the value of a change in a zero-phase current is the maximum undergoes a predictive ground fault accident when the maximum of the value in the change of the zero-phase current of each distribution line is a set value of predictive ground fault sensitivity or above and when it continues for a preset ground fault test time. CONSTITUTION:As to data on distribution lines 1,2,3 and 4 inputted to an input port P1, the maximum of the absolute value of a difference between two respective values of digital values (data) D1, D2, D3 and D4 of the update zero-phase currents stored at every 0.5-second interval in a set 0 of memories under the control of a central arithmetic processing unit CPU and of digital values (data) D1', D2', D3' and D4' of the zero-phase current 15 seconds before measurements in 30 times) stored in other memories, is selected and this value of a change is subjected to an operation of comparison with the value of predictive ground fault sensitivity set beforehand, and when it exceeds the range of this value and when it continues for a preset ground fault test time, it is determined that the distribution line wherein the value of the change in the aforesaid zero-phase current is the maximum undergoes a predictive ground fault accident.