An investigation of the horizontally mounted insulators for HVDC stations

The results of investigations into the cause of certain flashovers which occurred in horizontally mounted insulators in HVDC stations are described. Insulators having various shed shapes were subjected to contamination and wet tests under horizontally and vertically mounted insulators, a slight reduction was found in the contamination withstand voltages of horizontally mounted insulators for some shed profiles. A shed shape is proposed as the optimum design for horizontally mounted insulators from the viewpoint of both contamination and wet withstand voltage