Question: In a circuit breaker the basic problem is to________________?

• 1. maintain the arc
• 2. extinguish the arc
• 3. transmit large power
• 4. emit the ionizing electrons

Question: The voltage appearing across the contacts after opening of the circuit breaker is called__________voltage.

• 1. recovery
• 2. surge
• 3. operating
• 4. arc

Question: Large internal faults are protected by_______________?

• 1. merz price percentage differential protection
• 2. mho and ohm relays
• 3. horn gaps and temperature relays
• 4. earth fault and positive sequence relays

Question: Directional relays are based on flow of____________?

• 1. power
• 2. current
• 3. voltage wave
• 4. all of the above

Question: Air blast circuit breaker is used for_____________?

• 1. over currents
• 2. short duty
• 3. intermittant duty
• 4. repeated duty

Question: Circuit breakers usually operate under______________?

• 1. transient state of short-circuit current
• 2. sub-transient state of short-circuit current
• 3. steady state of short-circuit current
• 4. after DC component has ceased

Question: D.C. shunt relays are made of_____________?

• 1. few turns of thin wire
• 2. few turns of thick wire
• 3. many turns of thin wire
• 4. many turns of thick wire

Question: Circuit breakers are essentially____________?

• 1. current carrying contacts called electrodes
• 2. arc extinguishers
• 3. circuits to break the system
• 4. transformers to isolate the two systems

Question: Circuit breakers are essentially______________?

• 1. current carrying contacts called electrodes
• 2. arc extinguishers
• 3. circuits to break the system
• 4. transformers to isolate the two systems

Question: In order that current should flow without causing excessive heating or voltage drop, the relay contacts should_________________?

• 1. have low contact resistance
• 2. be clean and smooth
• 3. be of sufficient size and proper shape
• 4. have all above properties