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–Cable Tester Manufacturer
Question: How to distinguish the quality of the cable fault tester? Answer: 1. The high-voltage shock flashover method of the cable fault tester can test the high-resistance leakage fault and high-resistance flashover fault of the cable. , Low-resistance short-circuit problem: How to distinguish the quality of the cable fault tester? Answer: 1. The high-voltage impact flashover method of the cable fault tester can test the high-resistance leakage fault, high Flashover resistance fault, low-resistance short-circuit fault and disconnection fault are an efficient, reliable and widely adaptable cable fault detection method. The high-voltage shock flashover method is to apply a shock high voltage at the beginning of the faulty cable to break down the fault point with an arc. Use the voltage sudden jump at the moment of fault breakdown as the test signal.
Ranging is performed by observing the time that this signal travels once between the fault point and the beginning of the cable. The current sampling method is often used to take test signals. The current sampling method uses the principle of electromagnetic induction, and uses the current transformer to pick up the current signal on the grounding wire to obtain the reflected signal of the electric wave current in the cable.
There is no electrical relationship with the high-voltage generator and mains, so it is particularly safe. The waveform obtained by the current sampling method has a clear characteristic inflection point of the reflected waveform, which is especially beneficial to the analysis and location of fault distance. However, the test waveform of the current sampling method is more complicated; the waveforms obtained by different types, different lengths, different fault distances, and different impulse high voltages are ever-changing, and are often far from the standard waveforms.
Misjudgment and misjudgment often occur due to the inability to grasp the waveform law. 2. The low-voltage pulse test method of the cable fault tester The low-voltage pulse test method of the cable fault tester is based on the low-voltage pulse moving forward in the cable, and the fault point will cause the reflection of the pulse wave. The distance to fault is calculated using the observed time difference between the transmitted pulse and the reflected echo pulse and the transmission speed of the traveling wave in the cable.
The bridge method of the cable fault tester can intuitively determine whether the fault at the fault point of the cable is an open circuit or a short circuit, and can directly measure the distance from the test end to the fault point. However, the low-voltage pulse rule does not apply to high-resistance leakage faults and high-resistance flashover faults. 3. The secondary pulse method of the cable fault tester is due to the shortcomings of the above-mentioned test methods, so it is required to develop a new test method that is both accurate and practical.
The second pulse method thus appeared. The advanced point of the secondary pulse method is to transform the complex waveform in the impact high-voltage flashover method into an extremely simple and easy-to-master short-circuit fault test waveform of the low-voltage pulse method. Anyone with a little training can quickly and accurately detect failures.
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