Reasons for using loop resistance tester to test high contact resistance of high voltage switch

1. Reasons for loop resistance tester

1. The reason for the accuracy of the loop resistance tester itself is to first ensure that the accuracy of the loop resistance tester used is completely correct.

2. Check the wiring terminals on the panel of the loop resistance tester to see if there is loose contact or oxidation.

3. Make sure the wiring of the loop resistance tester is correct, and check whether the voltage input line is connected to the inner side of the current output line.

4. The current clamp of the loop resistance tester ensures reliable contact with the tested product, avoiding excessive contact resistance and affecting the test results.

5. Ensure sufficient test time, and test according to the time specified by the national standard.

2. The contact resistance of the high-voltage switch itself is too large

1. Whether both ends of the high-voltage switch are grounded. If both ends are grounded, a parallel loop will be formed. The test result is the parallel value of the circuit resistance of the circuit breaker and the grounding resistance of the substation. The correct approach is that at least one end of the high-voltage switch is not grounded.

2. The surface of the dynamic and static contacts of the high-voltage switch is oxidized

3. There are mechanical impurities or carbides remaining between the moving and static contacts of the high-voltage switch

4. The pressure of the dynamic and static contacts of the high-voltage switch drops (such as mechanical jamming, contact spring breakage, annealing, etc., resulting in a drop in contact pressure)

5. The contact area of the dynamic and static contacts of the high-voltage switch is reduced (improper adjustment of the contact surface or displacement during operation, and multiple interruption of load current and short-circuit current can cause the effective contact area to decrease)