This high potential test aimed to test if bus bar will withstand its withstand voltage after being installed in the site or it will breakdown and to check the vacuum bottle integrity, also to measure leakage current and insulation between CB and ground.
High potential test for circuit breaker
Testing equipment required for high potential
- AC HI-voltage injection machine (100KV, 60HZ).
- Earthing Rod or Ground Discharge stick (coming with high pot tester)
- Megger 5KV DC Supply.
Mechanical and visual inspection
- All safety rules should be taken into consideration.
- breaker cleaning and house keeping
- Check all shipping devices removed.
- Inspect ground to switchgear ground bus.
- Ensure the adequate clearance (distance) between circuit test ends and to other Ground object and other phases (not under the test) and also with other electrical equipment’s to prevent flash over.
High potential Test connection and test procedure
- Test VCB withstand voltage: VCB should be close , inject voltage as per FAT value.
NOTE: When we conduct HIPOT Test for one phase, other remaining phases should be connected to Ground.
Use Ground discharge stick with high tension Electrical for discharge the voltage from the system after each High potential Test.
- Test CB withstand voltage: VCB should be open , inject voltage as per FAT value.
- measure insulation after high voltage test with CBs close and open status then inject 5 KV for 1 minute then record the value and compare it with the value before high voltage test.
NOTE: Use Ground discharge stick with high tension Electrical for discharge the voltage from the system after each High potential Test.
Industry coded for High potential test
NESC: National Electrical Safety Code
NFPA: National Fire Protection Association
NEC: National Electrical Code (2008 Edition)
ASTM: American Society for Testing and Materials
IEC: International Electrical Commission
IEEE : Institute of Electrical and Electronic Engineers
NETA : National Testing Association
Respect to author, some excellent selective information.