Distribution Arrester Research

Performance studies of mostly 21 kV distribution surge arresters were conducted through field surveys and laboratory tests at Ontario Hydro. Surveys indicate moisture ingress to be the most widespread cause of arrester failures. In laboratory tests of complete units, only 25% survived the required 65 kA discharge current and about 50%, a special 20 kA duty-cycle test, indicating a need for development of standard production tests. In mode-of-failure tests, substantial hazards were found to exist. Explosion-proof arrester designs do provide some degree of improvement, but more effective solutions could be realized with suitable fault-current clearing devices. The use of fuses for this purpose shows some promise, and so does a fault-clearing ground-lead disconnector, currently under development.