Leakage protector is different from circuit breaker and disconnector. Circuit breaker In addition to the opening and closing circuit function, it also has the short circuit protection function. Isolating switch Only the opening and closing circuit functions. Leakage protector In addition to the opening and closing circuit function and the short circuit protection function, it also has the leakage protection function (the leakage current varies from 30mA to 500mA).
Most building power supply and distribution systems adopt TN-C-S system 。 general setting Two level leakage protection switch 。 first stage Set at the main switch at the power inlet, that is, the leakage current value of the main switch at the power inlet is Level 4 of 300mA - 500mA (L1, L2, L3 and N lines); Level II The socket circuit set in the user switch box (no leakage switch is allowed for the suspended air conditioning circuit), and the leakage current value is Grade 2 of 30mA (L1 or L2 or L3 and N lines). Thus, the occurrence of electric shock accidents of electricity users is prevented and the reliability of safe operation of building power supply and distribution system is improved.
After the leakage protection switch fails to trip, the leakage current detection link of the leakage protection switch should never be removed. According to the phenomenon of fault tripping, analyze the cause of fault tripping and find out the solution. There are 6 kinds of fault tripping phenomena of leakage switch:
Type 1 ， The insulation of the electrical equipment is damaged, which leads to the fault tripping of the leakage switch when using electricity;
Type 2 ， The wet insulation strength of the line decreases, resulting in the fault tripping of the leakage switch when not using power;
Type 3 ， Accidental electric shock of human body leads to fault tripping of leakage switch;
Type 4, 5, 6 ， The wiring is incorrect during construction and installation, which leads to the fault tripping of the leakage switch when using electricity.
The detailed analysis is as follows ↓↓
Type 1: The insulation of the electrical equipment itself is damaged and the leakage occurs (the N line in the equipment is shorted to the PE line). As shown in Figure 1.
Symptom: When the socket circuit is powered, the leakage switch of the socket circuit trips.
Cause of fault: According to the analysis, the wiring is correct, so it is judged that the insulation of the electrical equipment itself is damaged and the leakage occurs (the N line in the equipment is shorted to the PE line).
resolvent: Replace or repair the electrical equipment.
Type 2: The wet insulation strength of the line decreases. As shown in Figure 1.
Symptom: When power is not used, the main leakage switch or socket circuit leakage switch in AL1 trips.
Cause of fault: After analysis, the wet insulation strength of the line is reduced, resulting in the leakage current exceeding the allowable leakage current value of the leakage switch. It may also be caused by short circuit.
resolvent: Dry the circuit to improve the insulation strength. Check if the circuit is caused by short circuit, and remove the short circuit fault.
Category 3: Someone gets an electric shock, and the main leakage switch or socket circuit leakage switch in AL1 trips. As shown in Figure 1.
Symptom: The main leakage switch or socket circuit leakage switch in AL1 trips.
Cause of fault: Someone got an electric shock.
resolvent: Strengthen the safety education of electricity use for all people to avoid electric shock accidents.
Type 4: The wiring was incorrect during construction and installation, and the N line was connected to the PE line in the lighting circuit. As shown in Figure 2.
Symptom: The socket circuit can use power normally. When the lighting circuit uses power, the main leakage switch in AL1 trips.
Cause of fault: Through analysis, the wiring is incorrect during construction and installation. The N line in the lighting circuit is connected to the PE line by mistake.
resolvent: Change the PE line in the lighting circuit to the N line.
Category 5: The wiring was incorrect during construction and installation, and the N wire and PE wire in the socket box were connected incorrectly. As shown in Figure 3.
Symptom: The lighting circuit can use electricity normally. When the socket circuit uses electricity, the socket leakage switch in ALY trips, and sometimes the general leakage switch in AL1 also trips.
Cause of fault: Through analysis, the wiring is incorrect during construction and installation. The N line and PE line in the socket box are connected incorrectly.
resolvent: Swap the N line and PE line in the socket box.
Category 6: The wiring was incorrect during construction and installation, and the N line and PE line were mixed in AL1 box. As shown in Figure 4.
Symptom: When socket circuit or lighting circuit is powered, the main leakage switch in AL1 trips.
Cause of fault: Through analysis, the wiring is incorrect during construction and installation. Mix the N line and PE line in AL1 box.
resolvent: At the load end of the main leakage switch of AL1 box, exchange the N line with the PE line.
