Investigation on the Evolution Mechanism and Faulty Characteristics Parameters of Breakdown Fault for Cable Terminal Tail Pipe

As a critical part of the safe operation of the power grid, cable terminals play a key role in the interconnection of different electrical equipment. According to cable terminal fault statistics, reports of breakdown faults near the cable terminal tail pipe have been increasing year by year. However, the mechanism behind terminal tail pipe breakdown faults is still unclear, making it difficult to achieve early warning for these faults. To address this issue, the variation characteristics of grounding current, temperature distribution and electric field distribution during the evolution of breakdown fault in cable terminal tail pipe were discussed in this paper. The alteration of grounding pathway and grounding current value subsequent to the complete cracking of the lead seal were analyzed. The iterative algorithm for calculating the steady-state temperature distribution inside cable terminal was proposed. The progression of insulation damage under the tail pipe was inferred from the calculated results of electric field distribution. Furthermore, the characteristic state quantities during fault development were conducted. By detecting these characteristic state quantities, early warning of the cable terminal tail pipe breakdown fault can be achieved.