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Working principle of loop resistance tester

time:2020/9/29   source:华天电力  reading:262 time

Many high-current electrical equipment in the power system need to accurately measure the resistance of the loop in preventive tests and handover tests. Therefore, loop resistance testers are widely used in electrical tests.


Micro Ohmmeter.png


1. Design of loop resistance tester


The loop resistance tester uses a high-reliability high-power integrated circuit, which is composed of a DC constant current source, a preamplifier, and an indicating device. It is a low-value resistance measuring instrument with milliohm and microohm ranges. The operation is simple, and the loop resistance, wire resistance, coil resistance, etc. can be measured with one key. And the test current can be automatically stabilized, ensuring the stability and reliability of the test data.


2. Measurement of loop resistance tester


When the loop resistance tester is measuring, the high-frequency switching power supply outputs a current of 100A or more, which is applied between the two end buttons of the measured resistance. The analog signal of the voltage drop generated by the current flowing through the measured resistance is collected by the sampling circuit, and after being amplified by the preamplifier, the converter converts the analog signal into a digital signal. Then the data is filtered and processed by the microprocessor, according to the principle that the current of the series circuit is equal everywhere.


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