Rated voltage

Each circuit breaker is designed to handle a certain range of voltage, so it can also be classified according to its rated voltage:

1. High voltage circuit breaker: Although there is no global standard, according to the regulations of the International Electrotechnical Commission (IEC), the rated value of circuit breakers used to control high-power transmission lines is 72.5 KV or higher. Single pole circuit breakers allow single-phase disconnection, which can improve stability and reduce overall fault time. High voltage direct current (HVDC) circuit breakers are used to handle the power generated and fed from renewable resources.

These types of circuit breakers typically use solenoid operated or disconnected circuit breakers, and due to heavy loads, they incorporate complex arc extinguishing media such as SF6 and CO2. Due to the importance of safety for high voltage, high-voltage circuit breakers almost always use various fault insurance, including:

Current transformer with protective relay; Overload and ground fault protection; Keep the shell at the line potential (live tank) or ground potential (no tank)

2. Medium voltage (MV) circuit breakers: Circuit breakers with a rated voltage between 1 and 72 KV are classified as MV circuit breakers. Circuit breakers with lower rated power (such as those used indoors) are usually installed in metal enclosed switchgear, while larger circuit breakers are used to protect feeders from the influence of substations.

The parameters of medium voltage circuit breakers are constrained by international standards such as IEC 62271, and protective relays and current sensors are almost always used instead of thermal or magnetic circuit breakers. Medium voltage circuit breakers can be further classified by their arc extinguishing medium:

The rated current of the vacuum circuit breaker exceeds 6300A and the rated voltage is as high as 40.5KV. They typically have a longer lifespan and require less maintenance.

The rated current of air circuit breakers is 6300A and above, although they often have adjustable tripping levels and delays. They are typically used for main power distribution in industrial applications.

SF6 circuit breakers are becoming increasingly popular in arc extinguishing oil media due to the growing concern for oil spill environments

3. Low voltage circuit breaker: Low voltage circuit breakers are used at a maximum voltage of approximately 1000Vac, including miniature circuit breakers (MCBs). They are most commonly used in homes and offices, and can be installed in multiple layers on distribution panels or switchgear for easy maintenance, reset, and replacement. Molded case circuit breakers use thermal or magnetic overload sensors with a rated current of up to 2500A.

Low voltage circuit breakers are divided into three types:

Type B will trip at 3 to 5 times the full load current

The C-type can withstand heavier loads, which are 5 to 10 times the full load current

The D-type has the maximum load handling capacity, ranging from 10 to 20 times the full load current.