Post Type Insulators

Post Type insulators are usually used in substations.  These insulators are constructed in the form of a cylinder.  The circular surface of the cylinder is corrugated to increase the leakage distance.  They are mounted on pedestals.  These insulators exhibit high resistance to puncture. 
Post insulators are used in areas with heavy pollution and risk of vandalism.  Slightly damaged post insulators will still have structural integrity and good excellent properties.  Hence, there is no interruption in power.  The damaged insulator can be replaced at the next opportunity.