Study on the circuit resistance and characteristics of poor contact in high-voltage cable lead seals

Defects causing electrical contact issues in high-voltage cable end seals occur frequently due to poor conductor crimping, loose connections, or solder joint failures. Inspection methods based on infrared detection technology and circuit resistance testing are important for preventing such defects. To fully understand the physical mechanisms of contact failure during the operation of high-voltage cable end seals, this study establishes a simulation model of circuit resistance using finite element analysis software. It analyzes changes in circuit resistance with different volumes of oxidation and fracture in the lead seal and conducts electro-thermal coupling simulations. The results indicate that as the oxidation and fracture volumes in the lead seal increase, the circuit resistance caused by oxidation changes at the milliohm level, making it difficult to detect with infrared technology. In contrast, resistance due to lead seal fractures can rise to the ohm level, potentially exceeding the thermal tolerance of the cable’s XLPE layer, leading to insulation damage.