How to correctly choose the leakage circuit breaker with proper operating current?

Promulgator : TAIXIDate : 2018-05-29Views : 84

If you want to choose a suitable Leakage Circuit Breaker can be understood from two aspects. It can help everyone. Let's take a look at it together with Xiaobian.

First, choose according to the purpose of use and where the electrical equipment is located
1. Protection against direct contact with electric shock. Because the danger of direct contact with electric shock is relatively large, the consequences are very serious. Therefore, a high-sensitivity earth-leakage circuit breaker should be used. For electric tools, mobile electric equipment and temporary lines, they should be installed in the circuit. Current leakage current breaker with 30mA operating time within 0.1s. For households with more household appliances, it is best to install them in the household energy meter.
If the electric shock is likely to cause secondary damage, such as high-altitude operation, an earth-leakage circuit breaker with an operating current of 15 mA and an operating time within US must 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 within US should be installed.
2. Indirect contact with electric shock protection. Indirect contact with electric shock in different places can cause different degrees of personal injury. Therefore, different earth leakage circuit breakers should be installed in different places. For locations that are vulnerable to electric shock, earth leakage circuit breakers are required. The risk of electric shock in wet places is much greater than that in dry places. Earth-leakage circuit breakers with an operating current of 15-30mA and an operating time of 0.1s should generally be installed. For electrical equipment in the water, a leakage circuit breaker with an operating current of 6-l0mA and an operating time within US should be installed. For an electrical device where 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 15mA or less and an operating time within US must be installed. For a fixed electrical equipment with a voltage of 220V or 380V, when the grounding resistance of the housing is less than 500fZ, a single unit may be equipped with an earth leakage circuit breaker with an operating current of 30mA and an operating time within 0.19. For large-scale electrical equipment with a rated current above 100A or a power supply circuit with multiple electrical equipment, an earth leakage circuit breaker with an operating current of 50-100mA can be installed. When the electrical equipment has a grounding resistance of 1000 or less, it can be installed. Current leakage circuit breaker 200-500mA.

Second, choose according to the normal leakage current of circuit and equipment
1. With a single-use earth leakage circuit breaker, the operating current should be greater than 4 times the leakage current during normal operation of the equipment.
2. For leakage circuit breakers in branch circuits, the operating current should be greater than 2.5 times the leakage current during normal operation of the line, and also greater than 4 times the leakage current of the electrical equipment with the largest leakage current in the line.
3. The earth-leakage circuit breaker or total network-protected earth leakage circuit breaker shall have an operating current greater than 2.5 times the leakage current of the normal operation of the power grid.

(1) If it is not easy to measure the leakage current of a line or an electrical device, estimate it according to the following empirical formula:
1. Electrical circuit for lighting circuit or residential life: current of leakage circuit breaker IDZ>ISJ/2000.
2. Power and lighting hybrid circuit: current leakage circuit breaker IDZ > ISJ/1000.

(2) IDZ in the formula is the leakage breaker action current, and ISJ is the maximum current in the circuit.
1. For a single-phase 220V power supply for electrical equipment, use a two-pole two-wire or one-pole two-wire leakage circuit breaker.
2. Three-phase three-wire 380V power supply of electrical equipment, should use three-pole four-wire or four-pole four-wire leakage circuit breakers.