In this note, we are going to know About SF6 Circuit Breaker or Sulphur Hexafluoride circuit breaker, also about its Construction, Working Principle, Advantages, and Disadvantages. Welcome to Poly Notes Hub, a leading solution for polytechnic notes for diploma engineering students.
Author Name: Arun Paul.
What is SF6 Circuit Breaker?
An SF6 circuit breaker is a type of circuit breaker that uses sulfur hexafluoride (SF6) gas as an insulating and extinguishing medium to extinguish arcs during electrical current interruptions. SF6 circuit breakers are widely employed in high-voltage systems, such as substations and power transmission networks.
Because of its great dielectric strength and strong thermal conductivity, SF6 gas extinguishes arcs extremely well. When an arc forms within the circuit breaker, the SF6 gas immediately absorbs the produced energy and extinguishes the arc, avoiding additional damage to the electrical equipment.
Construction of SF6 Circuit Breaker
Below shows the SF6 Circuit Breaker Diagram –
- Fixed Contact: The fixed contact is a stationary component of the circuit breaker that remains in place throughout operation. It is often made of a high conductivity material, such as copper or silver, and is intended to provide a reliable connection point for electrical current.
- Moving Contact: The moveable contact is a component of the circuit breaker that may be moved to create or break an electrical circuit. It is frequently linked to a mechanism that enables it to move in response to command signals. The moving contact is intended to maintain consistent contact with the fixed contact throughout operation.
- Insulated Nozzle: The insulated nozzle is a component that surrounds the fixed contact and directs the flow of SF6 gas during operation. It is intended to offer insulation while preventing SF6 gas leaking from the circuit breaker.
- Valve: The valve regulates the amount of SF6 gas that enters and exits the circuit breaker. To keep the SF6 gas inside the circuit breaker at the proper pressure and flow rate, it is usually operated manually or automatically.
- SF6 Gas: The insulating and extinguishing medium found in SF6 circuit breakers is called SF6 gas. It is a good electrical insulator that is colorless, odorless, nontoxic, and nonflammable. In order to extinguish arcs, SF6 gas is discharged into the arc chamber during operation from sealed receptacles inside the circuit breaker.
- Fixed Piston: During operation, the circuit breaker’s fixed piston, a stationary component, aids in compressing and storing SF6 gas. Its purpose is to keep the SF6 gas pressure inside the circuit breaker at the appropriate level.
- Movable Cylinder: SF6 gas is compressed during operation by the moving contact, which is housed in the movable cylinder. It responds to control signals by moving and aids in building up the pressure required to put out arcs inside the circuit breaker.
Working Principle of Sulphur Hexafluoride circuit breaker
The SF6 circuit breaker uses fixed and movable contacts to stop electrical current flow. When the circuit breaker is activated, SF6 gas is directed through an insulated nozzle to quickly cool and extinguish the arc. This efficient gas acts as both an insulator and an arc extinguisher. A valve mechanism regulates the flow of SF6 gas within the circuit breaker, providing precise control throughout operation. In addition, a stationary piston maintains appropriate pressure levels, and a moveable cylinder allows for the regulated release of SF6 gas during interruption. This synchronized movement of components allows the SF6 circuit breaker to safely and effectively block electrical currents in high-voltage systems.
Advantages
Below we listed some merits of this circuit breaker –
- It is a compact and lightweight circuit breaker.
- SF6 circuit breakers are sealed equipment, which eliminates the need for routine maintenance.
- These circuit breakers are designed to last a long time.
Disadvantages
Below we listed some demerits of this circuit breaker –
- SF6 circuit breakers can be more expensive.
- SF6 gas is colorless, odorless, and non-toxic, although it can displace oxygen in enclosed spaces, increasing the danger of asphyxiation if leaks occur in poorly ventilated places.
- There may be issues with the availability and supply of SF6 gas.
