- Test objective:
1. For contact Resistance, this test is aimed at measuring the resistance of the bus bar and for the circuit breaker after being
installed in the site to avoid high resistance which may be results from welding or installing in the site.
2. For high potential this test is aimed to measure and test the withstand of the insulations and isolators against the high voltage without breaking down.
- Required equipment:
• Micro-ohm meter Contact resistance device.
• High potential test kit.
- High potential AC test:
1. Insulation test by megger to test insulation by 5-kilo volt injection for 1 minute 3 phases line to line and line to ground.
2. Applying high potential AC voltage on the bus bar line to line and line to ground and the CB in a service position, protection relays are energized and the VTs are racked out.
3. Applying high potential AC (higher voltage level than first applying time) voltage on the bus bar line to line and line to ground and the CB in test position, protection relays are energized and the VTs are racked out.
4. Take the record of passing current in mille Amperes from the high potential test kit.
5. Insulation test by megger to test insulation by 5-kilo volt injection for 1 minute 3 phases line to line and line to ground.
6. Compare the insulation test results to gathers before and after the high potential test.
- Contact resistance test connection
1. Contact resistance device has 4 leads, two for current and others for voltage, it depends on current injection on the bus bar or circuit breaker then senses the voltage and calculates resistance by dividing voltage by current (ohm's law)
2. Check the BB torquing of all bolts and confirm the torque value as per factory inspection.
3. Connect current leads between the device in which you want to measure its resistance, connect voltage leads on the same terminals of current adjust 100A injection then hold your hand on the contact resistance pushbutton, after a few seconds the result will be displayed.
The HLY-200C contact resistance tester is developed by HUAYI electric, The test current is DC 100A, 200A. In the case of DC 100A, 200A can be directly measured contact resistance test results with a large-screen LCD display, and with data storage, print, time settings, and other functions, and another gear 50A, 150A for user selection; custom test time, maximum 599S, much larger than the standard requirements of 60S; resolution 0.01μΩ and very stable. The instrument adopts the current-voltage method test principle, namely four–wire method testing technology.
