Ans : The types of isolators are as follows :-
Vertical break type single, double or triple pole isolator consisting mainly of fixed soiled core type insulator support with rigid contacts and moving copper blade supported by operating rod insulator. These are generally used in traction system of about 25 kV.
Horizontal two rotating post, center break type isolator consisting of two insulator stacks of post type insulator mounted on a bearing and also rotatable about its vertical axis through 90°. In this type one insulator stack swings in clockwise direction and other in opposite direction in such a way that the contact arms swings in horizontal plane isolating at the center. This is used at the voltage upto 220 kV.
Horizontal break center rotating double break isolator consisting of three insulator stacks per pole having two insulator stacks fixed on sides and center insulator stack rotating. Fixed contacts are mounted on the top of each of the insulator stacks on the side. It can be used in case of all outdoor isolation of circuit breaker, transformer banks, lightning arrestors and also for line sectionalization.
Extra high voltage column isolator consisting of a two part pantograph on the top, revolving drive insulator, solid core type porcelain insulator acting as the main supporting unit, the operating cubical provided with all necessary auxiliary contacts & other contacts for supervision & control and a vertically erected steel tube support anchored to the concrete plinth.