NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
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NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
Author: Noyafa–POE Tester
Bridge cable manufacturer's experience in using high-voltage bridge cable fault tester and precautions Bridge cable manufacturer 1. Positioning of coiled cables Defect point location. The difference is that the measurement clamps are clamped at both ends of the cable, and there is no need to use low-resistance short-circuit lines. There is no auxiliary cable involved in the balance, and the calculation formula cannot have“2”. As follows: X=L×P1‰.
2. Can copper tape and steel tape be used as bridge arms? The positioning accuracy of the high-voltage bridge cable fault tester depends on the uniform resistance of the conductors. The cable factory does not necessarily weld copper tape and steel tape lap joints. The influence of positioning accuracy is very small, the steel belt should be careful, it may introduce large errors, you should be aware of it, and try to avoid using the steel belt for positioning. 3. Positioning of overhead cables The overhead cables are usually single-core, with only an insulating layer, and the defect points found in the water immersion withstand voltage test can also be located. The only difference from other coiled cables is that the grounding is extremely water. The ground of the instrument can be connected to the grounding point of the pool, or a copper tape can be placed in the water as a grounding electrode.
4. Multi-point defect point location Here, it is necessary to distinguish whether the defect point is a low resistance point or a breakdown point. Theoretically, the positioning ratio points to the center of gravity composed of multiple leakage currents, so the bridge method cannot locate multiple fault points. On the running cable, the fault overvoltage surge can occasionally cause multiple weak points of the cable to break down in sequence, resulting in multiple breakdowns.
However, the situation of multiple breakdown points is difficult to be consistent. As the DC voltage rises, the weakest point breaks down first, and most of the current flows. The position calculated according to the ratio is very close to this point. Remove this point and find the next point. In practice, the chances of encountering more than two points flowing at the same time are very few. It can be said that the probability of inaccurate positioning caused by multiple clicks is smaller than that of winning the jackpot. Therefore, there is no need to worry about the difficulty of positioning the bridge. Put on.
The low resistance point without breakdown, as the voltage increases, mostly translates into the breakdown point. For special low resistance points, such as poor insulation of batch materials, the positioning ratio is always about 50%, which is worthy of vigilance. 5. The difference between the phase-to-phase breakdown location and the previous example is only that the current should flow back to the bridge through the other core, so the other core of the phase-to-phase breakdown should be connected to the bridge ground.
In practice, it may be: phase-to-phase breakdown and phase-to-shield breakdown coexist. You might as well ground other cores and shields. Most of the results are: phase-to-phase breakdown and phase-to-shield breakdown are the same point. 6. The processing of the auxiliary wire core without good insulation may break down all phases and shields, and the auxiliary cable phase cannot be found. The method is: use a multimeter to select a phase with a larger insulation resistance as an auxiliary cable.
If they are all baked into one, it is a metallic short circuit, and other cables laid in parallel can only be used. If it is not enough, only temporary auxiliary cables can be placed. High-voltage bridge cable fault tester experience and precautions Bridge cable manufacturer Shenzhen Noyafa Electronic Technology Co., Ltd.
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