A preliminary technical analysis on unusual insulation of the handcart cabinets in 35 kV circuit breaker in a 110 kV substation is carried out

which is put into operation in February

1999.The technical analysis focuses on the support insulators of switch and busbar

the air convection inside and outside 35kV switchgear cabinet

the clear distance between conductors

the dielectric property of insulating materials

the installation technique

the polluted dewdrop and the production technique of manufacturing plant etc.And the corresponding solutions are put forward

such as strengthening the cleaning

increasing the creepage distance

lowering the temperature difference inside and outside the handcart cabinet of circuit breaker

using the reinforced composite insulating materials

using anti-pollution insulator

smearing anti-pollution flashover coating over the insulator

using insulated bolts to connect insulating plates

installing insulation sleeve on the surface of current carrying conductor and so on.The implementation of some solutions is effective.