Insulation Resistance and Tracking Index of Circuit Breaker According to the Accelerated Aging Test

Abstract

This study examined insulation resistance and tracking index characteristics through the accelerated aging test of low-voltage circuit breakers. The leakage current was found to be influenced by external factors rather than the internal structure. Additionally, the insulation resistance of the circuit breakers undergoing accelerated degradation was measured using a Megger insulation tester. In the case of a circuit breaker manufactured using the accelerated aging test, the insulation resistance increased compared to that of a circuit breaker under normal conditions. However, the insulation resistance of aged circuit breakers collected from various regions of Korea exhibited a decrease in correlation with their equivalent lifetimes. The tracking test of the circuit breaker was conducted in accordance with IEC 60112. In the case of a circuit breaker under normal conditions, tracking did not occur even at an applied voltage of 400 V. Furthermore, no tracking was observed in the circuit breaker manufactured through the accelerated aging test. However, for the aged circuit breakers collected from various regions in Korea, tracking occurred even at an applied voltage of 125 V. Consequently, upon analyzing the circuit breaker components in relation to degradation, it was observed that, as degradation advanced, certain components were lost, and in the case of aged circuit breakers, the characteristics of the insulator were also compromised.