Technical Support

Troubleshooting of loop resistance tester

:2022-07-19 16:27:53:

1、Fault phenomenon: the loop resistance tester is connected to 220V AC power supply, the fan has no running sound, press the "test switch", and the ammeter and micro ohmmeter have no display.

Cause: 220V AC power supply is blocked, and the fuse is not installed or blown.

Troubleshooting: check and eliminate. (the fuse of 100A instrument shall not be less than 6A. If it blows again, please contact the manufacturer. (do not connect DC or 380V AC power supply)

2、 Fault phenomenon: press the "test switch" of the loop resistance tester, the ammeter displays no current, and the highest position of the micro ohmmeter displays "1".

Cause: 100A current circuit is not connected properly. The tested switch is not closed.

Troubleshooting: check the test line, reconnect, re clamp, and turn off the switch.

3、 Fault phenomenon: the test current of the loop resistance tester is normal, and the highest bit of the micro ohm value displays "1".

Cause: wrong position of voltage clamp. The measured circuit resistance exceeds 2000. The voltage signal line is disconnected or not connected.

Troubleshooting: process the voltage signal circuit and clamp the voltage clamp. Overrange: measure the voltage value of P1 and P2 with a multimeter, and the resistance value = voltage value / current value.

4、 Fault phenomenon: the output current of the loop resistance tester is dozens of times, less than 100A.

Cause: the power supply voltage is too low, the internal resistance of the power line is large or the contact is poor, and the voltage drop is too large when there is DC output, which is less than 190V. C1 and C2 terminals are loose. The circuit under test has poor contact with the test clip.

Troubleshooting: use a qualified power supply and use a too long and too thin power line to deal with the circuit under test, and eliminate poor contact. Tighten C1, C2, P1 and P2 terminals with appropriate force. (the test current is 30a, and the test value is credible)

Note: circuit resistance testers are generally possible, and most of them can be found in the above reasons, which can be solved by referring to relevant methods.


ZC-302D-100A contact resistance tester meets the standard of * power system standard DL/T845.4-2004. The tester is based on the combination of high-frequency switching power supply technology and digital circuit technology. It is applicable to the measurement of circuit resistance of switch control equipment. The test current of the tester is dc-100ma, which is recommended in the national standard. The tester can measure the loop resistance and display it in the monitor. Its accuracy and stability meet the requirements of most power systems for the maintenance of high-voltage switches and circuit resistance.

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