Recently, I received a customer’s inquiry about the high-voltage cable. The customer mainly wanted to figure out the reason for the damage of the high-voltage cable, so he asked the customer to send his high-voltage cable photos. Does the customer say that the connector part should be sent? The reply to the customer is Yes, so the customer sent a detailed photo of the product. After the engineer’s preliminary understanding, the customer’s high-voltage cable is likely to have a low-resistance fault.
Low resistance fault, cable insulation material is damaged, and ground fault occurs. The insulation resistance Rf is less than 10Z0 (Z0 is the wave impedance of the cable, generally between 10 and 40Ω). Generally, low-voltage power cables and control cables are more likely to have low-resistance faults on site. As the insulation is exposed to the air during the construction of the joint, moisture will also be absorbed in the insulation, which will leave hidden dangers for long-term safe operation. The third is that the installation process is not strictly followed or the process regulations are not considered for possible problems. Fourth, the DC withstand voltage test used in the completion acceptance test causes the formation of a back electric field in the joints and leads to insulation damage. Fifth, it is caused by improper sealing treatment. The intermediate joint must adopt a sealing structure with a metal copper shell and a PE or PVC insulating anticorrosion layer to ensure the tightness of the lead seal during on-site construction, which effectively guarantees the sealing and waterproof performance of the joint.
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