By hvhipot 
The loop resistance tester will inevitably encounter various abnormal problems in HV Hipot Electric Co., Ltd. daily use. Let’s briefly talk about how to solve these abnormal problems:
1. Phenomenon: The loop resistance tester is connected to 220V AC power supply, the fan is silent, and the “test switch” is clicked, the ammeter and micro-ohmmeter have no display.
Reason: 220V AC power supply is blocked, the fuse is not installed or is blown.
Elimination method: check and eliminate. (100A instrument insurance is not less than 6A, then contact the factory to solve it. (Never connect to DC or 380V AC power)
2. Phenomenon: Press the “test switch” of the loop resistance tester, the ammeter shows no current, and the highest position of the micro-ohm meter shows “1”.
Reason: The 100A current loop is not connected properly. The subject switch was not closed.
Remedy: check the test line, reconnect, and re-clamp. Close the switch.
3. Phenomenon: The test current of the loop resistance tester is normal, and the highest micro-ohm value displays “1”
Reason: The position of the voltage clamp is wrong. The resistance of the tested loop exceeds 2000. The voltage signal line is broken or not connected.
Remedy: deal with the voltage signal circuit, clamp the voltage clamp properly. When the range is exceeded: use a multimeter to measure the voltage values of P1 and P2, and the resistance value = voltage value/current value.
4. Phenomenon: The output current of the loop resistance tester is dozens of times less than 100A.
Reason: The power supply voltage is too low, the internal resistance of the power cord is large or the contact is poor, and the voltage drop is too large when there is a DC output, and it cannot reach 190V. The terminals C1 and C2 are loose. The circuit under test and the test wire clamp are in poor contact.
Remedy: Use a qualified power supply, use a power cord that is too long and thin, and deal with the circuit under test to eliminate poor contact. Use proper force when twisting the terminals C1, C2, P1, P2. (The test current is at 30A and the test value is credible)
When encountering the similar problems above, we can all solve it according to this method. The loop resistance tester generally may appear in the situation that is because of these several reasons. I hope the above explanation will be helpful to everyone.