SF₆ Circuit Breaker (SF₆ CB)
An SF₆ circuit breaker uses sulfur hexafluoride gas as an insulating and arc-quenching medium for high-voltage power system switching and fault interruption.
Working Principle:
When the breaker contacts separate under fault conditions, an electrical arc develops between them. SF₆ gas flows through the arc zone, cooling the arc and capturing free electrons through its electronegative properties. This accelerates dielectric strength recovery and enables successful current interruption, typically at a natural current zero in AC systems.
Main Components:
Fixed and moving contacts
Arc-interrupting chamber
SF₆ gas enclosure
Operating mechanism
Insulating supports
Gas density monitoring and alarm system
Advantages:
High dielectric strength and arc-quenching capability.
Compact design and reliable fault interruption.
Suitable for HV and EHV applications.
Low contact erosion under properly specified operating conditions.
Applications:
132 kV, 220 kV and 400 kV transmission substations.
Gas-insulated switchgear (GIS).
Power generation and transmission systems.
Industrial high-voltage installations.