The loop resistance tester, also known as the contact resistance tester, is an instrument used to measure the contact resistance and loop resistance of switch control equipment. There are several steps to use the loop resistance tester:

1. First, according to the four-wire measurement method, connect the test product to the instrument panel with the test wire. Note that the voltage measurement wire should be connected to the inside of the current output wire.

2. Then turn on the AC220V power supply. Note that the third wire of the power supply line, the protective ground, must be connected to the earth. Press the power switch, and the ammeter and resistance meter will display "000" (can be allowed to jump in one digit in the unnumbered ).

3. Press the measurement switch again, adjust the current output knob clockwise until the current meter head displays "100.0", then read the number on the resistance meter head to be the resistance value of the tested product, and record the data. (If "1" is displayed, it means the measured loop exceeds the range).

4. After the test is completed, turn the current output adjustment knob to small in the counterclockwise direction, reset the measurement switch, and then turn off the power switch. If you want to repeat the test, you only need to reset the measurement switch, re-clamp the test clamp, and then press the measurement switch.