In recent years, several serious fire disasters have occurred in high-voltage switchgear. The fire ignition mechanism and extinguishing method is not obtained. Because it is difficult to carry out the cable combustion test in full-size high-voltage switchgear. In this paper, a full-size test platform was built, and the temperature distribution of a switchgear during the electrical induced fire ignition was recorded. Secondly, the simulation model of the switchgear was constructed and the law of fire spread was mastered. Then, the process of cable material decomposition and the effect of material decomposition on cable combustion were analyzed. Finally, the start threshold of a fire extinguishing device was determined based on the temperature field distribution in the test. The results provide a reference for the design of fire extinguishing devices in high voltage switchgear.

combustion simulation; cable fault; numerical simulation; ignition mechanism; start-up threshold