Column-mounted medium-voltage circuit breakers encompass several types. The following are some of the common ones:

1. Oil-immersed Circuit Breakers

• Characteristics: Oil-immersed circuit breakers are early products that tend to be phased out due to their poor short-circuit breaking capacity, flammable oil, and potential for secondary accidents due to leakage. However, some oil-immersed circuit breakers may still exist in the power grid, and their short-circuit tripping function can be canceled during operation, allowing them to be used as load switches.

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2. Vacuum Circuit Breakers

• Characteristics: Vacuum circuit breakers come in both box-type and pole-type forms, with rated currents typically at 400A or 630A. They boast long mechanical lifespans and the ability to operate frequently, with rated current interruption capabilities reaching over 10,000 times and rated short-circuit breaking capabilities between 30 to 50 times. Furthermore, vacuum circuit breakers can be classified into different types based on insulation relative to earth, such as oil-immersed insulation, air insulation, and SF6 insulation.

• Applications: Vacuum circuit breakers are developing towards higher voltages and capacities, finding widespread application in power systems.

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3. SF6 Circuit Breakers

• Characteristics: SF6 circuit breakers offer numerous advantages, including strong short-circuit breaking capacity, multiple consecutive interruptions, frequent operation, low operational noise, and no fire hazard. They are excellent oil-free devices suitable for high-voltage applications. However, SF6 switches require attention to gas leakage checks after installation, especially within the first one to two months after new installation. Additionally, SF6 switches are not suitable for installation in cold regions because SF6 gas may leak or liquefy below -20°C, potentially causing switch explosions when interrupting short-circuit currents.

• Applications: SF6 circuit breakers are widely used in power systems due to their excellent performance, particularly in parts of the power system requiring advanced protection and control flexibility.

In summary, column-mounted medium-voltage circuit breakers mainly include oil-immersed circuit breakers (which are being phased out), vacuum circuit breakers, and SF6 circuit breakers. When selecting column-mounted medium-voltage circuit breakers, it is necessary to comprehensively consider specific power system requirements, installation environments, and budgets. Meanwhile, during installation and use, relevant regulations and operational requirements must be strictly adhered to ensure the safe and reliable operation of the equipment.