There are three main test methods of the loop resistance tester

Loop resistance testers, also known as transformer loop resistance testers, are mainly used to test the contact resistance of dynamic and static contacts of high-voltage circuit breakers. The circuit resistance of the circuit breaker mainly depends on the contact resistance of the dynamic and static contacts. The presence of contact resistance will increase. Loss of the conductor during energization increases the temperature of the contact point. Its value directly affects the current-carrying capacity during normal operation, and to a certain extent affects the ability to cut short-circuit current. It is also an important data reflecting the quality of installation and maintenance work. At present, the loop resistance tester mainly has three test methods, the specific operations are as follows:

1. Bridge method: When using a double-arm bridge to measure the resistance of the conductive circuit of the circuit breaker, due to the weak current flowing through the measurement circuit, it is difficult to eliminate the oxide film with large resistance, and it is difficult to measure too much value. The current is small, and it is difficult to form shrinkage at the contact point of the contact, ie, shrinkage resistance cannot be measured.

2. Voltage drop method: When a direct current is applied to the circuit under test, a voltage drop will be generated on the contact resistance of the circuit, the current value and voltage value passing through the circuit are measured, and the measured contact resistance will be calculated. The test process is cumbersome, and the measurement results are calculated manually, and there are certain errors.

3. Micro-ohmmeter method (loop resistance tester): The principle is the principle of voltage drop, but the measurement and calculation are handled by the single-chip microcomputer, which greatly reduces the workload.