Double-shed type, has the features of smooth shed without edge, open shed shape, large creepage distance, the inner shed smooth. Because this type is designed based on air flow resistance, has the good performance of self-cleaning by wind and rain, slow speed rate of collecting contamination, and easy to cleaning.
  Double shed type has the features of smooth shed without edge, open shed shape, good performance of self-cleaning, and slow speed rate of collection contamination, so as to collecting contamination amount is little than normal type insulator. This shed shape is easy for man-made cleaning, this is also one reason for little amount of contamination. And it suit to use for inner land and heavy pollution area. Because of large creepage distance, the unit insulator has the better antipollution withstand voltage, compared with normal type, if used double-shed type, would reduce insulator string length, and reduce the tower height.