Experience with AC hipot and partial discharge tests for commissioning generating station cables and switchgear

Test equipment is described which is suitable for AC hipot and partial discharge testing of 5 and 15 kV shielded cables of lengths up to about 600 m. The equipment can be used to test 5 and 15 kV metal-clad switchgear. Ontario Hydro´s experience at two nuclear generating stations using this AC test equipment is presented. The equipment can be used to assure the integrity of cable systems (less than 600 m long) already in service. The reasons for switching to AC testing of cable systems are outlined. Practical experience shows that the partial-discharge test is very effective in identifying installation problems in cables and switchgear. A number of problems are identified with the AC tests that a DC test would have missed