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
The test characteristics of the cable fault tester The cable fault tester manufacturer is used to solve the test of open circuit, short circuit, grounding, low resistance, high resistance flashover and high resistance leakage faults of power cables, as well as coaxial communication cables. The test characteristics of the cable fault tester and the local telephone cable cable fault tester manufacturer The cable fault tester is used to solve the test of power cable open circuit, short circuit, grounding, low resistance, high resistance flashover and high resistance leakage fault, and It is a special cable testing equipment for accurate testing of open-circuit and short-circuit faults of coaxial communication cables and local telephone cables. It can also test the cable path, burial depth, and the speed of the radio wave, and verify the cable length, etc., and can establish a cable file for daily maintenance and management. The cable fault tester adopts the acousto-magnetic synchronization method of waveform display to accurately locate the fault, which is a very accurate and unique fixed-point method.
When the high-voltage generator hits the faulty cable with DC high-voltage, the fault taps through and discharges, and the mechanical vibration generated by the discharge is transmitted to the ground, and the vibration signal is picked up by the high-sensitivity sensor. After amplification, it can be heard with headphones.“pop, pop”the sound of. This is the basic principle of traditional sonometry points. The traditional sound test method point instrument generally only uses earphones to monitor, or supplemented by the movement of the meter pointer to distinguish the discharge sound of the fault point.
Because the discharge sound is fleeting, and it is not much different from the ambient noise, it often brings great difficulties to operators who are not very experienced. The traditional acoustic measurement method of cable fault tester manufacturers is improved to be the acoustic-magnetic synchronization method, which uses the strong electromagnetic field signal at the moment of high-voltage shock discharge to trigger an indicator light to flash (or the needle to swing) to synchronize the sound. If you hear“pop, pop”When the indicator light flashes (or the needle swings) at the same time as the sound, it indicates that the sound heard is the discharge sound of the fault point.
The acousto-magnetic synchronization method has greatly improved the acoustic measurement method, but it still mainly relies on the human ear to judge the sound, and still has high requirements on the operator's experience. This instrument uses the discharge pulse magnetic field as a synchronization signal to digitally sample the sound and display the sound waveform. The waveform can be maintained continuously, avoiding the shortcoming of the transient sound, and the discharge waveform and noise at the fault point are obvious. What is more important is that the sound waveforms of multiple discharges are very similar. When the same sound waveforms of multiple discharges are observed, it can be clearly judged that the discharge sound has been collected. During the field test, the discharge sound of the fault point is often heard, but it is still difficult to accurately determine the location of the fault point based on the strength of the sound, especially when the cable is laid in the pipeline, the difficulty is even greater.
This problem can be solved by detecting the time difference between the electromagnetic signal and the acoustic signal. Since the propagation speed of electromagnetic signals is the speed of light, the time from the cable to the sensor can be ignored; while the speed of sound propagation is much slower, on the order of hundreds of meters per second; therefore, by detecting the relationship between electromagnetic and sound signals The time difference between them can be used to judge the distance of the fault point. When the sensor is continuously moved, the point with the smallest time difference between the acousto-magnetic and the magnetic field is found, and the fault point is below it.
It should be pointed out that since it is difficult to know the speed of sound propagation in the medium around the cable and the specific depth of the cable burial, it is impossible to accurately calculate the horizontal distance between the sensor and the fault point. Cable fault tester manufacturer Shenzhen Noyafa Electronic Technology Co., Ltd.
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