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 Length Tester
The occurrence of cable faults is often accompanied by the laying and use of cables, and the difficulty of locating cable faults gradually increases with different cable laying methods. Among them, the positioning of bridges, tunnels and ditches is relatively simple, and the positioning of direct burial is the most difficult. Next Xiaobian The generation of cable faults is often accompanied by the laying and use of cables, and the difficulty of cable fault location gradually increases with the different cable laying methods.
Among them, the positioning of bridges, tunnels and ditches is relatively simple, and the positioning of direct burial is the most difficult. Next, the editor will share some tips on using cable flaw detectors and other equipment to locate cable faults. When the nature of the fault is simple, special cable fault locating equipment such as a cable flaw detector can be used, which can be located within tens of minutes. When the fault is special, it often takes 4-5 days or even longer to locate the fault.
When using the echo method to locate cable faults, sometimes complex faults are transformed into simple faults by transferring the faulty phase and wiring method, and the fault location can be quickly determined to gain time for on-site line repairs, which is very important for power supply departments. crucial. Low-voltage power cables are generally multi-core cables. After a fault occurs during continuous use after laying, there are generally two-core and multi-core phase-to-phase or relative-to-ground short-circuit faults. Sometimes when it is detected that the fault waveform collected by a certain core is not ideal, it can be considered to switch the wiring to other faulty cores for fault waveform detection, and unexpected effects often occur. The collected and detected waveforms will become By comparing typical and rules, the specific location of the cable fault point can be quickly determined.
During the long-term on-site measurement of cable customers, it was found that after the failure of small-section copper-core directly buried power cables (35mm2 and below) and aluminum-core cables, short-circuit and disconnection faults may be accompanied at the same time. The difference between the short-circuit fault and the disconnection fault measurement is often done with less effort. For medium-voltage direct-buried power cables whose inner lining is extruded and armored, most of the faults are caused by external mechanical damage. When the insulation core fails, the inner lining may have been damaged. When encountering a special cable insulation fault, it is difficult to use a professional cable fault instrument to collect waveforms.
Consider using the acoustic method to apply high-voltage pulses directly between the steel tape and the copper shield of the cable, which tends to settle quickly. In the field measurement process, when using the acoustic measurement method to locate the fault of the low-voltage cable, when the high-voltage wire and the ground wire are connected between the bad phase and the metal shield or armor, the insulation resistance of the two is in a low-resistance metallic connection state, and the sound It is very small and cannot use the probe to monitor the fixed point, and the effect is not ideal. Through the actual listening to the side for many times, it is found that the distance between the discharge ball gaps is appropriately increased, and at the same time, the high voltage and grounding wires are reconnected between the two phases where the fault occurs, and the discharge sound will often become louder, and the fault point will be quickly determined .
I hope that the above techniques for locating cable faults using cable flaw detectors and other equipment shared by Xiaobian can be helpful to you.
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