Case Studies of Installation and Manufacturing Defects in 110kV HV Circuit Breaker Porcelain Insulators

1. SF6 gas leakage occurred in the ABB LTB 72 D1 72.5 kV circuit breaker.

Inspection revealed gas leakage at the fixed contact and cover plate area. This was caused by improper or careless assembly, where the dual O-rings slipped and were misplaced, resulting in gas leakage over time.

2. Manufacturing Defects on the Outer Surface of 110kV Circuit Breaker Porcelain Insulators

Although high-voltage circuit breakers typically have their porcelain insulators protected with covering materials during transportation to prevent damage, it remains extremely important to remove all coverings upon delivery and conduct a thorough inspection of the porcelain insulators. As shown in the figure, manufacturing defects may exist. While these defects might not immediately affect circuit breaker operation, it is crucial to notify the supplier and obtain feedback, especially when defects could deteriorate over time (such as enamel peeling) and eventually compromise the safe operation of the circuit breaker.