Differences between Air Circuit Breakers and Isolation Switches

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Differences between Air Circuit Breakers and Isolation Switches. There are many differences between air circuit breakers and isolation switches in terms of functions, structures, working principles, and application scenarios. The following is a specific introduction:

### Functions
- **Air Circuit Breakers**: They are mainly used for overload and short-circuit protection. When the current in the circuit exceeds the rated current or a short circuit occurs, the air circuit breaker will automatically trip and cut off the circuit to protect electrical equipment and lines from being damaged by overload and short-circuit currents.
- **Isolation Switches**: Their main function is to isolate the equipment under maintenance from the live parts when maintaining electrical equipment, forming an obvious break point to ensure the safety of maintenance personnel. Meanwhile, isolation switches can also be used for switching between different power sources or as a control means in some specific situations, but they cannot be used to cut off load currents and short-circuit currents.

### Structural Principles
- **Air Circuit Breakers**: Their internal structures are relatively complex and mainly consist of contact systems, arc extinguishing systems, release mechanisms, operating mechanisms, etc. When an overload or short-circuit fault occurs in the circuit, the release mechanism will detect the abnormal current and act quickly to separate the contacts and cut off the circuit. The arc extinguishing system will extinguish the arc at the moment when the contacts are separated to protect the contacts and reduce the impact on other equipment.
- **Isolation Switches**: Their structures are relatively simple and mainly composed of moving contacts, stationary contacts, insulating supports, operating mechanisms and other components. The moving contacts and stationary contacts are fixed by insulating supports and maintain a certain opening distance. The operating mechanism is used to control the opening and closing actions of the moving contacts to achieve circuit isolation.

### Working Characteristics
- **Air Circuit Breakers**: They have the functions of automatic tripping and automatic resetting. After the fault is removed, the power supply can be restored simply by manually closing the air circuit breaker. They have a relatively fast action speed and can cut off the circuit in a short time, playing an effective role in protecting the circuit.
- **Isolation Switches**: They do not have the function of automatic tripping, and their opening and closing operations need to be completed manually. When closing, it is necessary to ensure that the moving contacts and stationary contacts of the isolation switch are in good contact to ensure the normal conduction of the circuit; when opening, it is necessary to ensure that there is a sufficient safe distance between the moving and stationary contacts to achieve effective isolation.

### Application Scenarios
- **Air Circuit Breakers**: They are widely used in various electrical circuits in households, commercial and industrial fields as protection devices for terminal electrical equipment, such as the main switch and branch switches in household distribution boxes, and the control circuits of various electrical equipment, to prevent electrical accidents caused by overload or short circuit.
- **Isolation Switches**: They are often used in high-voltage substations, power plants, high-voltage distribution systems of industrial and mining enterprises, and the maintenance and isolation of large electrical equipment. In these places, isolation switches are usually used in combination with other switchgear such as circuit breakers to ensure the safe operation of the electrical system and the safety of maintenance personnel.