Compact 40.5kV air insulated metal enclosed switchgear with VCB is mostly used in power substation of 220kV and industry consumer with heavy loads. Practical operation of many years has proven that many faults had occurred in 40.5kV air insulated metal enclosed switchgear. Statistic date shows the most fault and failure is resulted from the poor insulation performance. Moreover, different discharge type will occur in the same insulation component used in different operation conditions of switchgears.

In this paper, the most common insulation components of spout and bushing used in air insulated metal enclosed switchgear were reviewed on faults and failures. Specially, simulation was implemented on the typical fault occurring in bushing, simulation results show that simulation is a useful tool used to analysing the defects of product design and manufacturing process.