Recently, Shenzhen Sipute Electrical Technology Co., Ltd., together with power supply bureau experts, conducted an on-site investigation and technical analysis of a front connector burnout failure that occurred at the Huiwang Electric project site.

The failure occurred in the front connector of a front connector + rear arrester combination system. After dismantling and analyzing the failed component, our technical team found that the damage was mainly concentrated on the outer layer of the stress cone. Ring-shaped and spot-like burn marks were observed at the interface between the stress cone insulation layer and the semi-conductive layer.

Based on the joint evaluation by field experts and Sipute engineers, the root cause of the failure was identified as follows: the outdoor cable termination head was not properly waterproofed, allowing moisture to enter the cable and migrate along the cable path toward the front connector. Continuous partial discharge occurred at the contact surface between the stress cone and the connector, eventually causing the connector to burn out.

Site Conditions and Technical Analysis

The outdoor cable termination was installed at a height of approximately 6 meters, while the total cable length was only around 20 meters. This installation condition made the cable more susceptible to water backflow and internal moisture migration.

After inspection, the possibility of discharge caused by dust particles was ruled out. Dust-induced discharge typically cannot produce a complete ring-shaped burn pattern. However, the circular burn marks observed in this failure are highly consistent with the characteristics of continuous surface discharge caused by moisture intrusion along the contact interface.

Key Lessons from the Failure

This incident once again demonstrates that the reliable operation of medium-voltage separable connector systems depends not only on the quality of the connector itself, but also on the waterproofing quality of the outdoor cable termination installation.

In outdoor applications, if the sealing of the cable termination head fails, rainwater may penetrate into the cable insulation system and migrate along the cable path to the connection point. This can lead to surface discharge, insulation breakdown, and ultimately severe damage to cable accessories.

Sipute Electrical’s Recommendation

Sipute Electrical would like to remind all engineering partners that strict waterproof sealing procedures must be followed during outdoor cable termination installation to prevent rainwater from entering the cable body and avoid potential safety hazards.

Going forward, our technical team will continue to strengthen project-site technical guidance and provide professional installation support to help customers eliminate similar risks and ensure the safe and stable operation of power distribution networks.

Sipute Electrical remains committed to empowering project implementation through technical services, working together with our partners to build safer and more reliable power distribution systems and achieve long-term mutual success.