Based on the DC artificial pollution tests

the flashover performances of six types of porcelain and glass insulators was analyzed and compared.The test results show that the insulators with different configuration and materials have different pollution flashover characteristics

the exponent a characterizing the influence of salt deposit density on flashover voltage depends on the configurations and materials

which varies within 0.32 and 0.55.Under the same pollution degree

the flashover voltage gradients of glass insulators are higher than those of porcelain insulators with the same configuration

while the flashover voltage gradients of outer-rib insulators are lower than those of anti-fog insulators.The effectiveness of creepage distance relates with insulator types and pollution degree

which can be denoted b

y K=M×（SDD）

m

.For the tested five types of non-standard insulators

the anti-fog glass insulators make good use of their creepage distance

while the two-outer-rib porcelain insulators have the lowest effectiveness of creepage distance.