Circuit Resistance Tester

1.This circuit resistance tester is developed in compliance with the SD301 departmental standard, as well as the DL403-91 and GB763 national standards, which require that the DC current used for measuring the main circuit resistance of high-voltage circuit breakers shall not be less than 100 A. Utilizing high-frequency switching power supply technology and digital circuit technology, this new-generation device features a compact size, lightweight design, and a constant-current-source output with high accuracy; it is equipped with an LCD display and a printing function, offers simple operation, and is highly portable, providing convenient measurement capabilities for professionals performing main circuit resistance measurements on high-voltage circuit breakers. This circuit resistance tester is based on the fundamental DC circuit calculation formula R = V/I and the principle that the current is equal throughout a series circuit. It employs a four-wire connection method; in the R = V/I calculation formula implemented by the instrument's microcontroller, the "V" represents the voltage drop across the load, which is divided by the current ("I") flowing through the circuit. The resulting value of "R" corresponds to the resistance of the load itself, excluding the resistance of the test leads. As a result, the test results are accurate—unlike those obtained using a multimeter or other resistance testers.