In China, the more common use of power cables is the […]
In China, the more common use of power cables is the last century since the 1960s, the level is limited, the use of a narrow range, was to solve the cable failure, research and development staff to produce a "flash method" principle of cable fault tester. The method of testing the cable failure of the instrument has three steps:
The first step with the distance meter to measure distance. In fact, first to determine whether the cable fault is high impedance or low resistance or ground, according to the conditions of using different test methods. If it is a ground fault, directly with the rangefinder low-voltage pulse method to measure the distance; if the high-impedance fault is to use high-pressure shock discharge method to measure the distance, with high-pressure shock discharge method when the distance and a lot of auxiliary Equipment: such as high-voltage pulse capacitor, discharge ball, current limiting resistor, inductance coil and signal sampler, etc., both trouble and unsafe operation, with a certain risk, more cumbersome is to analyze the sampling waveform, The knowledge of the requirements of relatively high.
The second step is to find the path (if the path is clear this step can be saved). In the search path, to give the cable plus a signal (path signal generator), and then receive the signal receiver, along the path of the signal to go again to determine the cable path. However, the scope of this path is roughly between 1-2 meters, not extraordinary and accurate.
The third step is based on the measured distance to accurately locate. It is based on the sound generated by the fire discharge, when the headset from the headset to hear the loudest place, that is, to find the location of the point of failure. However, because it is listening to the sound, so by the impact of environmental noise, find it quite time, sometimes to wait until the evening can be. When the cross-linked cable, it is more time, because the cross-linked cables are generally internal discharge, the sound is very small, almost can not hear, and finally only measured.
Therefore, in this way, this method can be used to solve most of the oil intrusion paper for the insulation of the power cable failure, for the past few years to cross-linked materials and polyethylene materials for insulating material cable failure, the test results are not too Ideal, because the fire caused by the discharge is often very small sound (the cable sheath is not damaged, but the cable internal discharge), encounter this situation, it is only by other means to solve.