Question

Which circuit breaker is preferred for high voltage up to \(765\ \text{kV}\) and extra high voltage system?

• A. Vacuum Circuit Breaker (VCB)
• B. Air Circuit Breaker
• C. \(SF_6\) Circuit Breaker
• D. Miniature Circuit Breaker (MCB)

Hint:

For high voltage and EHV systems, \(SF_6\) circuit breakers are preferred because \(SF_6\) gas has excellent insulation and arc-quenching properties.

Answer 1

The Correct Option is C

Concept: Circuit breakers are used to interrupt fault current and protect electrical systems. For high voltage and extra high voltage systems, the insulating and arc-quenching medium must be very effective.

Step 1: In high voltage systems, when contacts of a circuit breaker open, a strong arc is produced.

Step 2: This arc must be extinguished quickly to protect the system and equipment.

Step 3: \(SF_6\) gas has very high dielectric strength and excellent arc-quenching property.

Step 4: Due to these properties, \(SF_6\) circuit breakers are widely used in high voltage and extra high voltage systems.

Step 5: Vacuum circuit breakers are generally used for medium voltage applications, air circuit breakers for low voltage applications, and MCBs for domestic or low current protection. Therefore, the preferred circuit breaker is: \[ \boxed{SF_6\text{ Circuit Breaker}} \]