Author: Noyafa–POE Tester
The rough measurement method of the cable fault tester The rough measurement of the cable fault point is to measure the distance from the fault point to either end of the cable. This step is a necessary preparation for the fault location. There are many methods of rough measurement. According to the basic principle, there are two categories. One is the method of rough measurement of the bridge method cable fault tester. The rough measurement of the cable fault point is to measure the distance from the fault point to either end of the cable. The first step is the necessary preparation for fault location. There are many methods of rough measurement. According to the basic principle, there are two types, one is the bridge method, and the other is the pulse reflection method.
The traditional rough measurement method is to turn the high-resistance fault into a low-resistance fault after burn-through, and then use the bridge method or the low-voltage pulse reflection method to measure. In recent years, much attention has been paid to the detection of cable faults at home and abroad, and many methods have been studied successively. When using a flash tester to detect cable faults, it is no longer necessary to burn through the high resistance. You can directly add DC high voltage or shock high voltage to the fault point to make it flashover, and then measure the location of the fault point through the reflection of the flashover pulse.
DC Bridge Method for Measuring Short-Circuit and Grounding Faults The DC bridge method is the earliest method to detect cable faults, and it has been the main method for detecting cable faults for many years. For low-resistance grounding and phase-to-phase short-circuit faults, this method is still widely used and has high accuracy. It is generally required that the fault point resistance should not exceed 100kΩ, usually in 2kΩThe following is appropriate.
The DC bridge method is based on the principle of Wheatstone bridge, the wire core resistance on both sides of the cable fault point is introduced into the DC bridge, and the ratio is measured. From the measured ratio and the cable length, the distance from the measuring end to the fault point can be calculated. In the figure, RL is the single-core resistance of the full length of the cable, and RX is the resistance from the beginning to the fault point.
By measuring the resistance RX, the distance X from the starting end to the fault point can be calculated. When using the bridge method to roughly measure the fault point of the cable, a single-arm bridge, a double-arm bridge, etc. are commonly used, and the cable flaw detector is also made according to the principle of the bridge. Shenzhen Noyafa Electronic Technology Co., Ltd.
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