AdvancedTopic 75 of 106Electrical Engineering
Circuit breaker types
Air, vacuum, oil and SF6 breakers extinguish arcs differently.
In depth
Breakers interrupt fault current by extinguishing the arc at current zero. Air-blast, oil, SF₆ and vacuum interrupters suit different voltage levels; vacuum dominates medium voltage. Ratings include voltage, current, breaking capacity and operating time.
Key points
- Making and breaking capacity
- Transient recovery voltage
- Circuit-breaker vs isolator
ExampleA 33 kV vacuum breaker trips within about 3 cycles.
What is Circuit breaker types?
Air, vacuum, oil and SF6 breakers extinguish arcs differently.
Why is it important to understand circuit breaker types?
Breakers must interrupt large fault currents safely, and the way they extinguish the arc decides their suitable voltage and maintenance.
Why does an arc form when a breaker opens?
The current tries to keep flowing across the gap, and the ionised gas sustains the arc until it is quenched.
Why is SF6 used in breakers?
It has excellent insulation and arc quenching properties, but it is a potent greenhouse gas, so leakage must be controlled.
How is Circuit breaker types used in practice?
Typical applications include choosing a vacuum breaker for a medium-voltage switchgear panel, selecting an SF6 breaker for a high-voltage substation and specifying an air breaker for a low-voltage switchboard.
What should I learn before Circuit breaker types?
Study "Protective relays" first (topic 74 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
What are the key points of Circuit breaker types?
Making and breaking capacity. Transient recovery voltage. Circuit-breaker vs isolator.
Can you give an example of Circuit breaker types?
A 33 kV vacuum breaker trips within about 3 cycles.
What comes after Circuit breaker types?
The next topic is "Power system stability", which builds directly on this one.
How difficult is Circuit breaker types?
It is classed as Advanced in Electrical Engineering (topic 75 of 106). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Electrical Engineering.