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Detection Technology

Loop resistance tester to test contact resistance

time:2021/12/4   source:华天电力  reading:257 time

In order to ensure the safety of the circuit operation, we need to accurately measure the resistance data of the circuit. The loop resistance tester is such a tool, but many customers are worried about unstable performance because they don’t understand it for the first time. The measurement data is inaccurate, so that it is impossible to make an accurate judgment on the circuit situation, so that the circuit has a serious failure and brings huge losses to itself.


It will not be easily interfered by external magnetic fields, and its performance is particularly stable. It can quickly and accurately detect the resistance of the circuit that needs to be measured in a short time, allowing us to simply and clearly determine the fault of the circuit, thereby restoring the normal operation of the circuit . Therefore, customers must pay special attention when choosing, and choosing a good instrument will bring a higher return on detection value.


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There are two main reasons for the high contact resistance of the high-voltage switch tested by the loop resistance tester:


1. Reasons for loop resistance tester


1. For the accuracy of the tester itself, it is important to ensure that the accuracy of the resistance tester is completely correct.


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


3. Make sure that the resistance tester is wired correctly, and check whether the voltage input line is connected to the inside of the current output line.


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


5. Ensure sufficient test time, and carry out the 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 circuit will be formed. The test results are 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 static and dynamic contacts of the high voltage switch is oxidized.


3. Mechanical impurities or carbides remain between the moving and static contacts of the high-voltage switch.


4. The dynamic and static contacts of the pressure high-pressure switch drop (such as mechanical jam, contact bounce, annealing, etc., resulting in a drop in contact pressure).


5. The contact area of the moving and static contacts of the loop resistance tester is reduced. The static contact of the high-voltage switch is reduced (the contact surface is adjusted incorrectly or displaced during operation, and the load current and short-circuit current are repeatedly interrupted, resulting in a reduction in the effective contact area).


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