Residual Current Circuit Breaker : It is a kind of switching equipment to prevent the occurrence of human body electric shock or leakage in the low-voltage circuit causing fire and explosion accidents

Types of RCCB: Commonly used residual current circuit breakers are divided into voltage type and current type, and current type is divided into electromagnetic type and electronic type.

Function of RRCCB: Prevent personal electric shock. In the event of human body electric shock or equipment leakage, quickly cut off the power supply circuit to prevent human body and equipment from being harmed

Selection principle

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

1) Protection from direct contact with electric shock

Because direct contact with electric shock is more harmful and causes serious consequences, it is necessary to choose a leakage circuit breaker with higher sensitivity. For electric tools, mobile electrical equipment and temporary circuits, the operating current should be installed in the loop at 30mA, and the operating time is within rccb circuit breaker within 0.1s. For residential houses with more household appliances, it is best to install the electric energy meter after entering the household.

2) Indirect contact electric shock protection

For places that are prone to electric shock and more harmful, a rccb breaker with higher 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 an operating current of 15-30mA and an operating time of within 0.1s should be installed. For electrical equipment in the water, actions should be installed. The current is 6-10mA, and the operation time is within US. 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 rccb circuit breaker with an operating current of less than 15mA and an operating time within US should be installed. For fixed electrical equipment with a voltage of 220V or 380V, when the shell grounding resistance is below 500fZ, a single unit can install a  rccb 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 power supply circuits with multiple electrical equipment, a 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 Leakage circuit breaker with operating current of 200-500mA

Choose according to the normal leakage current of the circuit and equipment

1)rccb circuit breaker for single unit. The operating current should be greater than 4 times the leakage current during normal operation of the equipment.

2) rccbcircuit breakers used for branch circuits, the operating current should be greater than 2.5 times the leakage current during normal operation of the line, and at the same time greater than 4 times the leakage current of the electrical equipment with the largest leakage current in the line.

3) The leakage current of the main line or the leakage circuit breaker of the overall protection of the whole network should be greater than 2.5 times of the leakage current during the normal operation of the grid.

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

Lighting circuit or residential electricity circuit: the operating current of the leakage circuit breaker IDZ>ISJ/2000;

Power and lighting hybrid circuit: the operating current of the 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) Electrical equipment powered by single-phase 220V power supply should use two-pole two-wire or single-pole two-wire leakage circuit breakers.

2) Electrical equipment powered by three-phase three-wire 380V power supply should use three-pole four-wire or four-pole four-wire leakage circuit breaker