A Circuit Breaker is a switchgear that can automatically cut off the current when a circuit experiences overload, short circuit or other abnormal conditions, protecting the circuit and equipment. According to the usage environment, working principle and voltage level, circuit breakers can be further classified into several types:

Classified by working voltage
Low-voltage circuit breakers (LV) : They are used in household, commercial and light industrial circuits, with a general voltage not exceeding 1000V. They mainly protect circuits and electrical equipment. Common types include miniature circuit breakers (MCB) and molded case circuit breakers (MCCB).
High-voltage circuit breakers (HV) : They are used in industrial, power transmission and distribution systems, with voltages generally above 1kV. They can cut off large currents and protect the safety of power grids. Common types include oil circuit breakers, gas-insulated circuit breakers (GIS), and vacuum circuit breakers.
Classify by arc extinguishing method
Air circuit breaker (ACB) : It uses air as the arc-extinguishing medium and is suitable for medium and low voltage circuits.
Vacuum circuit breaker (VCB) : Arc extinguishing is completed in a vacuum environment, suitable for high-frequency operation and with a long service life.
Oil circuit breaker (OCB) : It uses oil as the arc-extinguishing medium and is suitable for high-voltage lines.
Gas circuit breaker (SF6 CB) : Arc extinguishing with sulfur hexafluoride gas, suitable for high-voltage and ultra-high-voltage systems.
Classified by use
Protective circuit breaker: Mainly used for overload and short-circuit protection.
Control-type circuit breaker: It is used for the on-off control of circuits and also has a protective function.

Circuit breakers not only protect circuit equipment from damage, but also ensure personnel safety, enhance the reliability and stability of system operation, and are indispensable key components in modern power systems and industrial automation.