Elements of a Circuit Breaker
Circuit breakers hold the following elements, irrespective of the medium for arc quenching and insulation:
- Main contact at system voltage;
- Insulation, like as porcelain, oil or gas, among the main contacts and ground potential;
- Operating and supervisory accessories, of that tripping facilities are most important.
A huge variety of closing and tripping arrangements (using relays along with variable time delay) and a number of operating mechanisms (based on solenoids, charged springs or pneumatic arrangements) are available now-a-days.
The categories of breakers used in a distribution system are:
- Air break type;
- Oil break type;
- Vacuum type; and
- SF6 gas breaker.
The rated voltage of circuit breakers for 33 kV level is 36 kV, and for 11 kV, it is 12 kV. The short circuit current rating is 25 kA. The 11 kV switchgear is commonly metal enclosed indoor type.