Development of a pin-post insulator with built-in metal oxide varistors for distribution lines

A 6.6 kV pin-post insulator, incorporating ZnO varistors, has been developed in order to reduce line faults caused by direct lightning strikes, thereby reducing and simplifying maintenance work on distribution systems. The developed insulators are interchangeable with conventional pin insulators and can withstand internal fault currents twice upon their failures. The simulated results regarding the response of the developed insulators to direct lightning strikes on an overhead ground wire agreed well with the experimental results. Simulation studies also revealed that installing the developed insulators on every two poles reduces the line-fault rate of present distribution lines in case of direct lightning strikes by 33%, while installing them on every pole reduces the rate by 97.5% or about 1/40 of the original value.