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A high-voltage combination switch (also called a high-voltage combination electrical appliance, such as a switch cabinet) is a device in a power system that integrates multiple functions and is used for the control, protection and measurement of high-voltage power lines. It is usually composed of components such as circuit breakers, disconnectors, grounding switches, current transformers, voltage transformers, and lightning arresters, which are compactly installed in a cabinet to improve the system's operating reliability, save space, and simplify installation.
Function
The main functions of high-voltage combination switches include:
1. Circuit breaker protection: The circuit breaker in the high-voltage combination switch can automatically cut off the fault circuit when the power system is overloaded or short-circuited, protecting electrical equipment from damage.
2. Control circuit: Through the circuit breaker or disconnector, the combination switch can realize manual or automatic control of the power line to meet the operation and dispatching needs of the power grid.
3. Measurement and metering: The current transformer and voltage transformer inside the combination switch can be used to monitor parameters such as current and voltage to help operation and maintenance personnel understand the line operation status.
4. Isolation function: The integrated isolating switch can isolate the equipment from the power system under no-load conditions, which is convenient for inspection and maintenance.
5. Grounding protection: The grounding switch can provide grounding operation to prevent personal injury caused by accidental energization of the power system during inspection.
Classification
The classification of high-voltage combination switches is usually based on structure, installation method, application and voltage level.
1. Classification by structure
- Metal-enclosed combined switch (GIS): All main equipment such as circuit breakers, isolating switches, transformers, etc. are installed in a metal-enclosed gas-insulated chamber, using sulfur hexafluoride (SF6) gas as the insulating medium. This design is suitable for occasions with limited space or poor environmental conditions, such as urban substations.
- Air-insulated combination switch (AIS): Using air as the insulating medium, the equipment is usually more dispersed and suitable for occasions with more space.
2. Classification by voltage level
- High-voltage combination switch: Usually suitable for voltage levels of 72.5kV and above. Widely used in the protection and control of high-voltage transmission lines.
- Medium voltage combination switch: usually used for voltage levels between 1kV and 72.5kV, used in medium voltage power distribution systems.
3. Classification by installation method
- Outdoor combination switch: designed for outdoor installation, can adapt to various weather conditions, widely used in substations and switch stations.
- Indoor combination switch: used for indoor installation, usually small in size, suitable for factories and distribution rooms.
4. Classification by functional module
- Fixed combination switch: all equipment is fixedly installed, suitable for occasions where load changes are not frequent.
- Drawer combination switch: each device is installed in a removable unit, which is easy to maintain and replace, and suitable for occasions with large load changes.
Advantages
- Space saving: The combination switch equipment has a compact structure and occupies a small area, especially GIS type equipment.
- Improve safety: Since key equipment (such as circuit breakers and disconnectors) are integrated in a closed system, external interference is reduced and the safety of operation is improved.
- Reduce maintenance costs: The closed design of the combination switch can effectively isolate external environmental factors (such as dust and moisture), reducing the maintenance workload.
Application scenarios
High-voltage combination switches are widely used in substations, distribution stations, industrial enterprises and other places, especially in urban centers, high-voltage transmission lines and new energy power generation systems such as wind power and solar power.
