To understand the variation of DC breakdown characteristics of silicone rubber insulation materials

sili-cone rubber materials were frozen at low temperature in a constant-temperature test chamber. Ball-ball electrode and rod-plate electrode were employed to simulate the nonuniform electric field. The change regularity of DC break-down voltage of silicon rubber with different aluminum hydroxide contents with temperature was measured

and cor-responding mechanism was analyzed. And the volume resistivity was also measured. Results show that: 1)with the temperature lowering

the DC breakdown voltage of the silicone rubber material rises first and then tends to be sta-ble;2)for the same low temperature treatment

the DC breakdown voltage of the silicone rubber with relative con-tent of 130%aluminum hydroxide gets the maximum; and 3)applying positive polarity DC voltage

the breakdown voltage of the silicone rubber insulation material is smaller

compared with that under negative polarity DC voltage.