FAULTTPOINT RANGING UNIT FOR POWER CABLE

摘要

PURPOSE:To attain ranging to an insulation-breakdown fault point of a power cable at any time by eliminating dead time, by providing high-frequency filter, where a frequency component of more than a specific frequency is allowed to pass, to both the ends of the power cable. CONSTITUTION:A surge is detected by current transformers provided to both ends of power cable 1. When the output voltage of high-frequency filter 3 which allows a component of this surge higher than a frequency value expressed by formula I to pass is higher than a noise level, pulse generator 4 connected to this high- frequency filter 3 generates a pulse. A pulse generated by pulse generator 4 at terminal B is transmitted to hour meter 5 at terminal A via cable 10, and a pulse generated at terminal A is also transmitted to hour meter 5. Hour meter 5 calculates arrival time difference (tA-tB) between pulses transmitted from terminals A and B, so that ranging to a fault point will be performed according to the difference. Consequently, ranging to the insulation-breakdown fault point of a cable is done at any time without dead time.