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–CCTV Tester
Question: How did the cable failure occur Answer: The cable failure occurred due to a weak point in the core insulation, which may have been formed during the cable production process, but more often during the installation of the cable, or It is in the cable question: how does the cable failure happen? Answer: The cable failure occurs due to a weak point in the insulation of the wire core. This weak point may be formed during the cable production process, but more often it is formed during the cable laying and installation process. The initial operation of the cable may be trouble-free, but with the operation of the cable, there will be various overvoltages, such as lightning overvoltage or switching overvoltage, ( Generally, the time of occurrence is short.) These overvoltages will cause instant flashover breakdown of the weak point of the wire core insulation, and the circuit breaker will trip. At this time, if the cable is reclosed, the cable can still run, but the phenomenon of frequent trips will occur. With the increase of the number of trips, the time interval gradually shortens. In this stage, the insulation of the weak point of the core is further deteriorated, the insulation resistance is gradually reduced, and the insulation of the core is transformed from a high-resistance state to a low-resistance state. A short circuit occurs between the conductors of the cable, and sometimes a strong short-circuit current will blow the faulty core or the entire cable. Therefore, when we intervene at different times, we will find that the cables are in different states, namely flashover breakdown state, high resistance state, low resistance state, short circuit state, core open circuit state, and cable open circuit state.
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