For extra high voltage transmission lines, the circuit breaker preferred is -

The correct answer is 'option 3'

Solution:

The voltage levels of different circuit breakers are given below:

Additional Information

Advantages of SF₆ circuit breaker: ​

• The SF₆ gas is  non-flammable and chemically stable.
• Their decomposition products are non-explosive and hence there is no risk of fire or explosion.
• Electric clearance is very much reduced because of the high dielectric strength of SF₆.
• It gives noiseless operation.
• There is no over-voltage problem because the arc extinguishes at natural current zero.
• There is no reduction in dielectric strength because no carbon particles are formed during arcing.
• It requires less maintenance and no costly compressed air system is required.
• SF6 performs various duties like clearing short-line faults, switching, opening unloaded transmission lines, transformer reactor, etc. without any problem.