Question 1

What is restriking voltage?

Accepted Answer

A) The transient voltage that appears across the circuit breaker contacts at the instant of arc extinction. 
B) The transient voltage that appears across the circuit breaker contacts at the end of arc extinction. 
C) Both (a) and (b) 
D) None of the above 
A) The transient voltage that appears across the circuit breaker contacts at the instant of arc extinction. 
B) The transient voltage that appears across the circuit breaker contacts at the end of arc extinction. 
C) Both (a) and (b) 
D) None of the above A

Question 2

In a circuit breaker, the active recovery voltage depends upon which among these?

Accepted Answer

A) Circuit conditions. 
B) Power factor. 
C) Both (a) and (b) 
D) None of the above 
A) Circuit conditions. 
B) Power factor. 
C) Both (a) and (b) 
D) None of the above C

Question 3

For a current upto 10A which material is used as the fusing element?

Accepted Answer

A) Copper 
B) Silver 
C) Alloy of lead and tin 
D) Zinc 
A) Copper 
B) Silver 
C) Alloy of lead and tin 
D) Zinc C

Question 4

What is fusing factor?

Accepted Answer

A) The ratio of current rating of the fuse to the minimum fusing current 
B) The ratio of minimum fusing current to the current rating of the fuse 
C) The ratio of maximum fusing current to the current rating of the fuse 
D) The ratio of minimum fusing current to the voltage rating of the fuse 
A) The ratio of current rating of the fuse to the minimum fusing current 
B) The ratio of minimum fusing current to the current rating of the fuse 
C) The ratio of maximum fusing current to the current rating of the fuse 
D) The ratio of minimum fusing current to the voltage rating of the fuse

Question 5

How is the restriking voltage measured?

Accepted Answer

A) RMS value 
B) Peak value 
C) Instantaneous value 
D) Average value 
A) RMS value 
B) Peak value 
C) Instantaneous value 
D) Average value

Question 6

When using air blast circuit breaker, current chopping is a phenomenon observed when

Accepted Answer

A) A long overhead line is switched off. 
B) A bank of capacitors is switched off. 
C) A transformer on no load is switched off. 
D) A heavy load is switched off. 
A) A long overhead line is switched off. 
B) A bank of capacitors is switched off. 
C) A transformer on no load is switched off. 
D) A heavy load is switched off.

Question 7

For a high speed circuit breaker what will the total clearing time?

Accepted Answer

A) Few minutes. 
B) Few seconds. 
C) 1 to 2 cycles. 
D) 5 to 20 cycles. 
A) Few minutes. 
B) Few seconds. 
C) 1 to 2 cycles. 
D) 5 to 20 cycles.

Question 8

Which type of air is used in air blast circuit breaker?

Accepted Answer

A) Ionised air 
B) Air free from moisture 
C) Air should have least CO2 
D) Air must have oil mist. 
A) Ionised air 
B) Air free from moisture 
C) Air should have least CO2 
D) Air must have oil mist.

Question 9

Why is the resistance switching used in a air blast circuit breaker?

Accepted Answer

A) Reduce the magnitude of fault current. 
B) Control the CB operating time. 
C) Damp out the fast transient. 
D) Change the fault current power factor. 
A) Reduce the magnitude of fault current. 
B) Control the CB operating time. 
C) Damp out the fast transient. 
D) Change the fault current power factor.

Question 10

In axial blast type of CB, expansion of air takes place from ______________.

Accepted Answer

A) High pressure to low pressure. 
B) Low pressure to high pressure. 
C) Always in high pressure. 
D) Always in low pressure. 
A) High pressure to low pressure. 
B) Low pressure to high pressure. 
C) Always in high pressure. 
D) Always in low pressure.

Question 11

What is the interrupting medium in the contactor?

Accepted Answer

A) Air at atmospheric pressure. 
B) SF6 gas 
C) Oil 
D) All of the above. 
A) Air at atmospheric pressure. 
B) SF6 gas 
C) Oil 
D) All of the above.

Question 12

What is the type of air blast in cross blast type CB?

Accepted Answer

A) The blast of air is along the ar(
C)  
B) The blast of air cuts across the ar(
C)  
C) Both (a) and (b) 
D) None of the above. 
A) The blast of air is along the ar(
C)  
B) The blast of air cuts across the ar(
C)  
C) Both (a) and (b) 
D) None of the above.

Question 13

Why is it difficult to interrupt a capacitive circuit?

Accepted Answer

A) The current has a leading power factor. 
B) The restriking voltage can be high. 
C) Current magnitude is very small. 
D) Stored energy in the capacitor is very high. 
A) The current has a leading power factor. 
B) The restriking voltage can be high. 
C) Current magnitude is very small. 
D) Stored energy in the capacitor is very high.

Question 14

Recovery voltage is the value of rms voltage that reappears across the poles of a circuit breaker before_______________

Accepted Answer

A) Restriking voltage 
B) Final arc extinction 
C) Rise of voltage 
D) All of the above 
A) Restriking voltage 
B) Final arc extinction 
C) Rise of voltage 
D) All of the above

Question 15

The interrupting time of a circuit breaker is the period between the instant of _________.

Accepted Answer

A) Initiation of short circuit and the arc extinction on an opening operation. 
B) Energizing the trip circuit and the arc extension on an opening operation. 
C) Initiation of short circuit and the parting of primary arc contacts. 
D) Energizing of the trip circuit and the parting of primary arc contacts. 
A) Initiation of short circuit and the arc extinction on an opening operation. 
B) Energizing the trip circuit and the arc extension on an opening operation. 
C) Initiation of short circuit and the parting of primary arc contacts. 
D) Energizing of the trip circuit and the parting of primary arc contacts.

Question 16

On what factor does the rate of rise of restriking voltage (RRRV) depend?

Accepted Answer

A) System voltage. 
B) Circuit power factor only 
C) Switching conditions 
D) Both (b) and (c). 
A) System voltage. 
B) Circuit power factor only 
C) Switching conditions 
D) Both (b) and (c).

Question 17

Which among the following statement is true related to fuse?

Accepted Answer

A) Greater the current smaller is the time taken by the fuse to blow out. 
B) Greater the current greater is the time taken by the fuse to blow out. 
C) The current is directly proportion to the blow out time of fuse. 
D) Is dependent on the temperature and atmospheric conditions. 
A) Greater the current smaller is the time taken by the fuse to blow out. 
B) Greater the current greater is the time taken by the fuse to blow out. 
C) The current is directly proportion to the blow out time of fuse. 
D) Is dependent on the temperature and atmospheric conditions.

Question 18

What is the breaking capacity of the air blast circuit breaker?

Accepted Answer

A) 5000 MVA 
B) 6000 MVA 
C) 7000 MVA 
D) 10000 MVA 
A) 5000 MVA 
B) 6000 MVA 
C) 7000 MVA 
D) 10000 MVA

Question 19

What is the maximum current upto which fuses can be used?

Accepted Answer

A) 25 A 
B) 50 A 
C) 75 A 
D) 100 A 
A) 25 A 
B) 50 A 
C) 75 A 
D) 100 A

Question 20

Which among these is the least expensive protection for over current in low voltage system?

Accepted Answer

A) Rewirable fuse. 
B) Isolator. 
C) Circuit breaker. 
D) Air breaker switch. 
A) Rewirable fuse. 
B) Isolator. 
C) Circuit breaker. 
D) Air breaker switch.

What is restriking voltage?

In a circuit breaker, the active recovery voltage depends upon which among these?

For a current upto 10A which material is used as the fusing element?

What is fusing factor?

How is the restriking voltage measured?

When using air blast circuit breaker, current chopping is a phenomenon observed when

For a high speed circuit breaker what will the total clearing time?

Which type of air is used in air blast circuit breaker?

Why is the resistance switching used in a air blast circuit breaker?

In axial blast type of CB, expansion of air takes place from ______________.

What is the interrupting medium in the contactor?

What is the type of air blast in cross blast type CB?

Why is it difficult to interrupt a capacitive circuit?

Recovery voltage is the value of rms voltage that reappears across the poles of a circuit breaker before_______________

The interrupting time of a circuit breaker is the period between the instant of _________.

On what factor does the rate of rise of restriking voltage (RRRV) depend?

Which among the following statement is true related to fuse?

What is the breaking capacity of the air blast circuit breaker?

What is the maximum current upto which fuses can be used?

Which among these is the least expensive protection for over current in low voltage system?

Electrical Protection and Circuit Breakers

Electrical Protection and Transmission Line Characteristics

Power System Protection and Equipment

Electrical Protection and Safety: Part A

Electrical Protection and Safety: Part B

Protective Relays and Circuit Breakers for Electrical Systems

Electric Arc and Circuit Breaker Protection

Electrical Components and Circuit Breakers

Electrical Protection and Switchgear

Relaying Schemes and Techniques for Electrical Equipment Protection

Understanding Relays for Power System Protection

Filters

Exam 7: Circuit Breakers and Fuses

What is restriking voltage?

In a circuit breaker, the active recovery voltage depends upon which among these?

For a current upto 10A which material is used as the fusing element?

What is fusing factor?

How is the restriking voltage measured?

When using air blast circuit breaker, current chopping is a phenomenon observed when

For a high speed circuit breaker what will the total clearing time?

Which type of air is used in air blast circuit breaker?

Why is the resistance switching used in a air blast circuit breaker?

In axial blast type of CB, expansion of air takes place from ______________.

What is the interrupting medium in the contactor?

What is the type of air blast in cross blast type CB?

Why is it difficult to interrupt a capacitive circuit?

Recovery voltage is the value of rms voltage that reappears across the poles of a circuit breaker before_______________

The interrupting time of a circuit breaker is the period between the instant of _________.

On what factor does the rate of rise of restriking voltage (RRRV) depend?

Which among the following statement is true related to fuse?

What is the breaking capacity of the air blast circuit breaker?

What is the maximum current upto which fuses can be used?

Which among these is the least expensive protection for over current in low voltage system?

Electrical Protection and Circuit Breakers

Electrical Protection and Transmission Line Characteristics

Power System Protection and Equipment

Electrical Protection and Safety: Part A

Electrical Protection and Safety: Part B

Protective Relays and Circuit Breakers for Electrical Systems

Electric Arc and Circuit Breaker Protection

Electrical Components and Circuit Breakers

Electrical Protection and Switchgear

Relaying Schemes and Techniques for Electrical Equipment Protection

Understanding Relays for Power System Protection

Filters