(a) porcelain (glazed brown) ;
(b) Glass.
Both (a) and (b) consists of the following types:
(I) pin type;
(ii) strain type;
(iii) suspension.
The pin type insulator is mostly used for Low Tension ( L.T) lines. It is also employed on High Tension (H.T) transmission or 6.6kv , 11kv and 33kv where the poles are placed in a straight line.
The strain type insulator is used for H.T. transmission system for voltages up to 33kv where the bends in route direction have wide angles. The suspension insulator is for H.T. systems operating at voltages above 33kv, where the poles or pylons are fixed in a straight line.
