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Problems encountered in the maintenance and testing of the loop resistance tester

Time: 2022-04-11 Author: 铧正 Click: 835 Time

    The loop resistance tester is widely used in the measurement of contact resistance, loop resistance, cable and wire, and welding seam contact resistance of various life electrical control switches in enterprises. The high-precision loop resistance tester developed and produced by our company has accurate measurement data and performance comparison. Stable, in line with the requirements of China's electric power and power supply management departments based on on-site high-voltage switch maintenance and high-voltage switch factory loop resistance.

    So how to maintain the loop resistance tester?

    The loop resistance tester should be placed in a dry, ventilated, dust-free, corrosive-gas-free room, should not be stacked in a wooden box, and should be stored with the panel facing up. The bottom of the device should be covered with moisture-proof items to prevent the device from getting wet.

    Several common problems in the field test of the loop resistance tester:

    1. The voltage wiring circuit is open or has poor contact (when the wiring is open, it can be seen that the contact resistance is infinite). When there is strong electromagnetic interference around the test, such as when the bus is being charged, the charged bus will interfere with the two voltage test lines of the tester through the capacitor with air as the medium. A differential mode voltage appears. First of all, if the influence of external environmental interference is large, the loop resistance tester will display a value much larger than the resistance value of the test object. At this time, if the system test staff have sufficient field test experience, they may be able to judge by judging Abnormal test analysis results, and solve the problem of development, can also attract attention and finally get the correct test research results, but if there is not enough experience between testers, it may misjudge the switch loop resistance value exceeding the standard, and may use power outage maintenance. The method mainly deals with defects, which will cause some unnecessary losses to the production and life of the power company in the future. Secondly, if the interference intensity is not very large, the display value of the instrument is just within the qualified resistance range of the circuit breaker, which is the same as the situation of "poor contact of the voltage circuit", which will also lead to misjudgment.

    2. In most cases, the circuit breaker wiring terminal will produce an oxide film or oil film on the outer surface of the terminal block after long-term operation, which may occur when the voltage test claw of the loop resistance tester is connected to such a terminal board. The contact is poor, and the voltage test wire claw itself produces a certain contact resistance. When the contact resistance value is equal to the internal resistance value of the voltage sampling circuit, it will seriously affect the test results.

    3. Open the voltage wiring circuit, open the loop resistance tester, and there is no strong electric field interference at the test site. In this case, since the differential mode voltage input by the amplifier basically does not exist, the test parameters displayed by the loop resistance tester are close to 0. . If the loop resistance tester has enough field test experience, it can determine the abnormal voltage loop test line as the loop resistance test line. Electricians suggest that the final correct test result can be obtained after eliminating the abnormal test line of the instrument voltage loop. On the contrary, it may misjudge the problem of the tester, interrupt the test, replace or repair the tester, prolong the power outage time, and bring unnecessary trouble to the test work.

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Loop Resistance Test Instrument

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