NEWS & KNOWLEDGE

Leakage Circuit Breaker refers to a switch that can automatically act when the leakage current in the circuit exceeds a predetermined value. Commonly used leakage circuit breakers are divided into voltage type and current type, and current type is divided into electromagnetic type and electronic type. Leakage circuit breakers are used to prevent personal electric shock and should be selected according to the different requirements of direct contact and indirect contact.

Leakage circuit breakers are usually selected according to the use and the location of electrical equipment

1. Prevent direct contact with electric shock

Since direct contact with electric shock is more harmful and can cause serious consequences, it is necessary to choose a more sensitive leakage circuit breaker. For power tools, mobile electrical equipment and temporary lines, the working current should be installed in a 30mA loop, and the working time should be within 0.1s of the leakage circuit breaker. For houses with more household appliances, install an electric energy meter after entering the home.

If electric shock may cause secondary damage (such as high-altitude operation), a leakage circuit breaker with a working current of 15mA should be installed in the circuit. For electrical medical equipment in hospitals, a leakage circuit breaker with a working current of 6mA should be installed.

2. Prevent indirect contact with electric shock

Indirect contact and electric shock in different places can cause different degrees of personal injury. Therefore, different leakage circuit breakers should be installed in different places. For places that are prone to electric shock, a leakage circuit breaker with high sensitivity is required. The risk of electric shock in a humid place is much greater than in a dry place. Generally, a leakage circuit breaker with a working current of 15-30mA and working time within 0.1s should be installed.

For electrical equipment in the water, measures should be taken. The current is 6-10mA, and the working time is within the US range. For electrical equipment where the operator must stand on a metal object or in a metal container, as long as the voltage is higher than 24V, a leakage circuit breaker should be installed, and its working current should be less than 15mA. For fixed electrical equipment with a voltage of 220V or 380V, when the grounding resistance of the shell is lower than 500fZ, a single device can be equipped with a leakage circuit breaker, the working current is 30mA, and the working time is within 0.19.

For large-scale electrical equipment with a rated current of more than 100A or power circuits with multiple electrical equipment, a leakage circuit breaker with a working current of 50-100mA can be installed. When the grounding resistance of electrical equipment is lower than 1000, a leakage circuit breaker with a working current of 200-500mA can be installed.

- Feb 27, 2021-