In modern society, the fields of industry, agriculture, transportation, national defense, education and health, finance, commerce, tourism, services and people＇s life are inseparable from the electricity important link in the generation, transportation and use of electricity. Distribution systems include transformers and various high and low voltage electrical equipment. Low-voltage circuit breakers are a wide range of electrical equipment.

Low voltage circuit breaker, which is from the structure, it uses the feature points, there is universal type (also known as frame, internationally known as ACB) and plastic shell type [internationally known as MCCB, MCB (small)] two categories, their role is the same:

(1) under normal circumstances, do not frequent, sub circuit, or start, stop motor;

(2) the circuit can be automatically cut off when the circuit or motor is overloaded, short circuit or under voltage (voltage is not enough).
According to the different protection objects, the circuit breaker is divided into four types:

(1) distribution protection type - protective power supply and electrical circuit (wire, cable) and equipment;

(2) motor protection type - specially designed for motor less frequent start, interruption during operation, and protection of motor during overload, short circuit and under voltage;

(3) protection for household and similar domestic places - protection of lighting circuits, household appliances, etc.;

(4) residual current (leakage) protection type - protector used to protect people from electric shock and to prevent electrical fire.