Impulse Breakdown Characteristics of 13.2 kV Covered Conductor Insulator/Tie Configurations

Utility companies which use covered conductors on 13.2 kV primary distribution systems have experienced a number of outages due to burndown conductors. Burndown is believed to result from a stationary arc, triggered by a lightning induced surge, in the insulator/tie region melting and separating an overhead conductor. An experimental investigation has been carried out to determine the lightning impulse characteristics of two types of insulator and four types of cable tie, used in conjunction with covered conductors on 13.2 kV distribution systems. The results obtained are discussed in terms of two types of prebreakdown events.