SF6 (Sulfur Hexafluoride) circuit breakers, or SF6 breakers, are industrial devices used to replace outdated circuit breaker equipment in the electrical industry, offering greater safety and more convenient features. Today, we will present detailed information about the structure of SF6 circuit breakers as well as the working principle of SF6 circuit breakers. This is to help our customers better understand this new type of electrical equipment and its outstanding benefits.
The operating procedure of SF6 circuit breakers primarily creates a safer working environment for electrical workers, minimizing risks for operators.
SF6 Circuit Breakers
SF6 circuit breakers are electrical devices used to switch high-voltage circuits in all operating modes:
- No-load operation
- Rated load operation
- And fault conditions.
Among these, short-circuit current switching is the most demanding operating mode. The process of switching high-voltage circuits always involves many potential hazards, risks, and incidents that can affect human lives as well as cause significant economic losses.
The advent of SF6 circuit breakers with high safety levels has made a significant contribution to the development of the electrical industry.
SF6 circuit breakers are designed and manufactured for all high voltage levels, from a small 3kV to 800kV, due to their superior features:
- High breaking capacity.
- Compact size.
- High safety and reliability.
- Long product lifespan with low maintenance costs.
Structure of a 220kV SF6 Circuit Breaker
The structure of a 220kV SF6 circuit breaker typically has 2 main parts:
- The switching section.
- The arc-quenching section.
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- Breaking chamber
- Insulators
- Support column
- Breaking spring
- SF6 gas cylinder
- SF6 pressure gauge and monitoring unit
- Grounding terminal
- Drive rod
- Circuit breaker status indicator
SF6 circuit breakers use SF6 gas as the arc-quenching medium because it does not corrode the internal components of the switching device, and due to its thermal properties. The switching mechanism includes the busbar system, contacts, spring assembly, and electric motor.
SF6 gas is compressed and stored in a high-pressure tank. When a circuit is interrupted, the high-pressure SF6 gas is discharged through the arcs inside the circuit breaker.
After the arc is quenched, the temporarily decomposed SF6 is recovered because most of it recombines to its original state and is contained in a low-pressure device. It is then compressed back into the high-pressure storage tank for reuse.
Sulfur hexafluoride gas is used only for insulation and arc quenching. If the SF6 pressure in the contact chamber does not meet the specified requirements, the arc-quenching and insulation capabilities are not guaranteed. At this point, it is necessary to recharge the SF6 gas and check for leaks.
Operating Procedure – Working Principle of SF6 Circuit Breakers
The operating procedure of the transformer – The working principle of the SF6 circuit breaker is as follows:
♦ When a trip signal is received, the drive shaft 4 rotates and pulls the moving system of the breaking chamber (including the moving arcing contact 2, the moving working contact of the cylinder 6, and the insulating nozzle 9) to move linearly downwards.
♦ Simultaneously, the SF6 gas compressed in the cylinder 6 flows through the working contact system first, then to the arcing contact system.
♦ After the arc is generated, the nozzle 9 is released from the arcing contact 8. The compressed gas is discharged and extinguishes the arc. Typically, each breaking unit will have a gas pressure gauge and a supplementary gas charging valve.
In SF6 circuit breakers, the arc is quickly extinguished immediately upon arc blowing. For self-blast piston-type circuit breakers, only about 20% of the energy of the drive mechanism is required, thus necessitating only a compact drive unit.
The equipment operates reliably, with low noise levels and higher reliability. Therefore, SF6 circuit breakers are often preferred for use in substations because they require a very small installation area but offer very high safety.
Besides SF6 circuit breakers, there are also other types of circuit breakers such as oil-immersed arc-quenching circuit breakers and vacuum or compressed air arc-quenching circuit breakers. However, SF6 circuit breakers still lead in this field in terms of safety and convenience.
The following personnel are required to thoroughly understand the operating procedure of SF6 circuit breakers:
- Technical staff of the technical department, safety technical department, testing team, electromechanical workshop, production dispatch team.
- Technical staff directly involved in power transmission.
- Technical staff and operators of 220kV, 500kV substations, etc.
If you have any further questions regarding the operating procedures of SF6 circuit breakers and the structure of SF6 circuit breakers, please contact us. For SF6 gas purchases, please contact our Hotline for accurate pricing at different times. We guarantee the quality of the gas in terms of purity, origin, and accompanying services.
> See more: What is a circuit breaker, the structure of a high-voltage vacuum circuit breaker
