Influence of attachment of insulating string on AC flashover strength of insulator

The relation between ac flashover voltage (ACFOV) and an attachment of nylon string on the insulator surface is studied in air by using a PMMA insulator which has a backside electrode. The measurements show that the ACFOV is decreased by the attachment of the string. ACFOV characteristics can be classified into two types with the contact angle between the H.V. electrode and the insulator surface. In a region of the contact angle from 90/spl deg/ to 120/spl deg/, the maximum percentage of the decrease is 15%. In the other region of the angle from 120/spl deg/ to 180/spl deg/, the maximum decrease is 25%.