With the rapid development of our country’s economy, the demand for electricity is also increasing, and the development of the power industry has made more and more contributions to society. Power transmission and transmission are also valued by the power sector. Loop resistance is a sign of whether the conductive loop is well connected. They are all important parameters, and their value affects the current carrying capacity and short-circuit current cut-off ability of normal operation. When doing preventive tests and handover tests, electric workers need to accurately measure the power transformers, switches, and switches in the power system. The loop resistance value of circuit breakers and other high-current equipment mainly depends on the loop resistance between the moving and static contacts. Therefore, the loop resistance of power transformers, switches, circuit breakers and other equipment operating in the power grid has become safe operation Important parameters for assessment and acceptance.
So what is the main method of using this loop resistance tester when electric power workers are doing experiments? how to use?
Since the loop resistance tester works under the condition of high current, in order to eliminate the lead resistance and improve the measurement accuracy, the four-wire connection measurement method is adopted. At the same time, in order to avoid overheating, the current duration is required to be short and the use of a firm For current wiring, the detection points are selected uniformly according to the requirements of the regulations. When the loop resistance tester outputs current, the output value of the loop resistance tester is directly compared with the reading on the digital display screen of the DC high-power active standard resistor. Can maximize the accuracy of measurement.
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 terminal buttons of the measured resistance, and the sampling circuit collects the voltage drop caused by the current flowing through the measured resistance After the analog signal is amplified by the preamplifier, the analog signal is converted into a digital signal by the A/D converter, and then the data is filtered, calculated, and processed by the microprocessor. According to the principle of equal current in the series circuit, Ohm's law is passed R=U/I, the DC resistance value of the measured body is obtained from the ratio of the voltage drop U at both ends of the load and the current I in the loop.
The loop resistance tester uses a high-reliability high-power integrated circuit, which is composed of a DC constant current source, a preamplifier, an A/D converter, an indicating device, etc. It is a low-value resistance with a range of milliohms and micro-milliohms. The measuring instrument is easy to operate. It can measure loop resistance, wire resistance, coil resistance, etc. with one key, and the test circuit can automatically stabilize the current, ensuring the stability and reliability of the test data.