Question

The voltage rating of the circuit breaker is normally from _________ times more than the normal operating voltage.
1. 1.05 – 1.10
2. 1.10 – 1.15
3. 1.15 – 1.20
4. 1.20 – 1.50

Answer 1

Correct Answer - Option 1 : 1.05 – 1.10

Concept:

Rated Voltage of Circuit Breaker:

The rated voltage of the circuit breaker depends upon its insulation system.

For below 400 KV systems, the circuit breaker is designed to withstand 10% above the normal system voltage.

For an above or equal 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 load conditions the voltage level of a power system is allowed to rise up to the highest voltage rating of the system.