Author: Noyafa–CCTV Tester
What are the test techniques for EHV cable sheath faults? The operation mode of extra-high voltage cable (single-core cable) stipulates that the sheath (or sheath, shield) can only be grounded at a single point to eliminate the formation of induced voltage and circulating current. The sheath single-point grounding usually uses two types of square EHV cable sheath faults. What are the test techniques? The operation mode of ultra-high voltage cable (single-core cable) stipulates that the sheath (or sheath, shielding layer) can only be grounded at a single point to eliminate the formation of induced voltage and circulating current. Two schemes are usually used for single-point grounding of the sheath: (1) When the cable length is short, one end is directly grounded, and the other end is grounded through the sheath voltage protector; (2) When the cable is long, one end is directly grounded, and the other end is grounded. Use cross-connect method.
The fault of the EHV cable sheath is a ground fault, that is, there is a second grounding point. The traditional methods are: bridge method for distance measurement, acoustic measurement method or step voltage method for positioning. Due to the great influence of the environment, the fixed-point effect of the acoustic measurement method or the step voltage method is not good, which is time-consuming and labor-intensive.
The EHV cable sheath fault tester is a new principle of EHV cable sheath fault location device. The bridge method does not require a reference loop and does not require a proportional calculation! Compared with the traditional acousto-magnetic synchronous acoustic measurement point, it is not disturbed by ambient audio noise! Compared with the traditional step voltage method, which is limited to the fixed point of the directly buried cable, this device is suitable for various cable laying conditions! Three functions of pre-positioning, path and fixed point in one! 1. Equipment composition and function The ultra-high voltage cable sheath fault tester consists of the following three parts: 1) Wireless remote control integrated high-voltage source 2) Ultra-high voltage cable sheath fault tester 3) When locating the fault of the high-voltage bridge: the high-voltage source and the The faulty cable to be tested is reliably connected to form the high-voltage shock circuit of the system; When the fault is located: the intelligent visual and noise-free fixed point instrument detects the oscillating wave signal along the tested cable, and intuitively judges the location of the fault point according to the LCD Chinese display.
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