Types and principles of refusal to operate leakage circuit breakers

1. In the TN-CS system, if the detection circuit is between the PEN line and the L line of the TN-C section, the leakage on the PE line of the TN-S section will cause the leakage circuit breaker to refuse to operate.
2. In the TN-S system, since the circuit installer connects the N line to the switch, if the N line is disconnected, when leakage occurs on the L line, the leakage circuit breaker will refuse to operate because the detection circuit will not detect the leakage signal.
3. In the TN-CS system, since the circuit installer connects the N line and the PE line together, if leakage occurs, the leakage circuit breaker will refuse to operate.
4. During installation and use, if the sensitivity of the leakage circuit breaker is too low and the actual leakage value does not reach the specified value, it will also refuse to operate.

There are several main reasons for the false operation of the leakage circuit breaker:
1. In the TN-CS system, the circuit installer connected the PE line and the N line in reverse, which will cause false operation;
2. In the three-phase four-wire circuit used for lighting and power, the three-pole leakage circuit breaker was wrongly selected, and the neutral line of the load was directly on the power supply side of the protector, causing false operation;
3. There are high-power electrical appliances near the leakage protector, and electromagnetic interference generated when the electrical appliances are turned on and off will cause false operation;
4. The insulation resistance of the phase line and the neutral line is too low, and part of the current leaks to the earth through the leakage point, so that the current vector sum through the zero-sequence current transformer is not zero when the circuit is normal, causing false operation;
5. When the PE line of the electrical equipment casing is connected to the working neutral line, it causes false operation;
6. The three-phase power line passing through the three-phase leakage protector does not pass through the zero-sequence transformer in the same direction, resulting in false operation;
7. During installation and use, the leakage circuit breaker will also malfunction due to the selection of too high sensitivity.