How to choose leakage circuit breaker

How to choose the leakage circuit breaker? For everyone's safety, we must pay attention to the selection principle of leakage circuit breakers. Here, I would like to share with you, I hope everyone can benefit:

One: choose according to the normal leakage current of the circuit and equipment

1 The leakage current circuit breaker of the main line or the whole network shall be operated, and its operating current shall be greater than 2.5 times of the leakage current during normal operation of the power grid.

2 leakage circuit breakers for single machine. The operating current should be greater than 4 times the leakage current during normal operation of the device.

3 Leakage circuit breakers for branch lines, the operating current should be greater than 2.5 times the leakage current of the line during normal operation, and also greater than 4 times the leakage current of the electrical equipment with the largest leakage current in the line.

Second: If it is not easy to measure the leakage current of lines or electrical equipment, it can be estimated according to the following empirical formula:

Lighting circuit or residential electricity circuit: operating current of leakage circuit breaker IDZ>ISJ/2000; power and lighting hybrid circuit: operating current of leakage circuit breaker IDZ>ISJ/1000

In the formula, IDZ is the operating current of the leakage circuit breaker, and ISJ is the maximum current in the circuit.

1 Three-phase three-wire 380V power supply electrical equipment, should use three-pole four-wire or four-pole four-wire leakage circuit breaker.

For single-phase 220V power supply electrical equipment, two-pole two-wire or single-pole two-wire leakage circuit breakers should be used.

2 Three-phase three-wire 380V power supply electrical equipment, should use three-pole four-wire or four-pole four-wire leakage circuit breaker.

Three: choose according to the purpose of use and the place where the electrical equipment is located

1 direct contact with electric shock protection

Because the direct contact with electric shock is relatively serious, the consequences are serious. Therefore, it is necessary to use a high-sensitivity leakage circuit breaker. For power tools, mobile electrical equipment and temporary lines, the operating current should be 30mA in the circuit. Leakage circuit breaker within 0.1s. For residential buildings with more household appliances, it is best to install them in the household electric energy meter.

If it is easy to cause secondary injury (such as working at height), an earth leakage circuit breaker with an operating current of 15 mA and an operating time of US should be installed in the circuit. For electrical medical equipment in hospitals, an earth leakage circuit breaker with an operating current of 6 mA and an operating time of US should be installed.

2 indirect contact with electric shock protection

Indirect contact with electric shock in different places can cause different degrees of damage to the human body. Therefore, different leakage circuit breakers should be installed in different places. For places with high risk of electric shock, it is required to use a leakage circuit breaker with high sensitivity. In a wet place, the risk of electric shock is much greater than in a dry place. Generally, an earth leakage circuit breaker with an operating current of 15-30 mA and an operating time of 0.1 s should be installed. For electrical equipment in the water, the action should be installed. The leakage current circuit breaker has a current of 6-l0 mA and an operating time of US. For electrical equipment that the operator must stand on a metal object or in a metal container, as long as the voltage is higher than 24V, an earth leakage circuit breaker with an operating current of 15 mA or less and an operating time of US should be installed. For fixed electrical equipment with voltage of 220V or 380V, when the grounding resistance of the outer casing is below 500fZ, the single-machine can install an earth leakage circuit breaker with an operating current of 30mA and an operating time of 0.19. For large electrical equipment with rated current above 100A or power supply circuit with multiple electrical equipment, an earth leakage circuit breaker with an operating current of 50-100mA can be installed. When the grounding resistance of the electrical equipment is below 1000, it can be installed. An earth leakage circuit breaker with an operating current of 200-500 mA.