For below 400 KV systems, the circuit breaker is designed to withstand ______above the normal system voltage. 

The correct answer is option 1

Concept :

Rated voltage of circuit breaker :

• For below 400 kV systems, the circuit breaker is designed to withstand 10% above the normal system voltage.
• For an above or equal to 400 kV system, the insulation of the circuit breaker should be capable of withstanding 5% above the normal system voltage.
• The voltage rating of the circuit breaker is normally from 1.05 to 1.10 times more than the normal operating voltage.
• this is because during no load or small loads condition voltage level of the power system is allowed to rise up to the highest voltage rating of the system