Question 1

What is the actuating quantity for the relays?

Accepted Answer

A) Magnitude 
B) Frequency 
C) Phase angle 
D) All of these 
A) Magnitude 
B) Frequency 
C) Phase angle 
D) All of these D

Question 2

A fuse wire of circular cross section has a radius of 0.8mm. The wire blows off at a current of 9(A) What will be the radius of the wire that will blow off at a current of 1A?

Accepted Answer

A) 0.2 mm 
B) 0.18 mm 
C) 0.28 mm 
D) 0.3 mm 
A) 0.2 mm 
B) 0.18 mm 
C) 0.28 mm 
D) 0.3 mm B

Question 3

Which among these tests are performed to check the nation or international standards?

Accepted Answer

A) Type test. 
B) Production tests. 
C) Site checks. 
D) All of the above. 
A) Type test. 
B) Production tests. 
C) Site checks. 
D) All of the above. A

Question 4

The making and breaking currents of a 3 phase ac circuit breakers in power systems are respectively in ________form.

Accepted Answer

A) rms value, rms value 
B) instantaneous value, rms value 
C) rms value, instantaneous value 
D) instantaneous value, instantaneous value 
A) rms value, rms value 
B) instantaneous value, rms value 
C) rms value, instantaneous value 
D) instantaneous value, instantaneous value

Question 5

Refer to the following facts to answer the question A 50 Hz, 11 kV, 3 phase alternator with earthed neutral having a reactance of 3 ohms per phase and is connected to a bus bar through a circuit breaker, if the distributed capacitance upto CB between the phase and neutral is 0.01 ? F. What is the frequency of oscillations?

Accepted Answer

A) 10000 Hz 
B) 12500 Hz 
C) 12628 Hz 
D) 13265 Hz 
A) 10000 Hz 
B) 12500 Hz 
C) 12628 Hz 
D) 13265 Hz

Question 6

A three phase circuit breaker is rated 2000 MVA, 33 kV. What will be its making current?

Accepted Answer

A) 35 kA 
B) 49 kA 
C) 70 kA 
D) 89 kA 
A) 35 kA 
B) 49 kA 
C) 70 kA 
D) 89 kA

Question 7

Which of the following circuit breakers has the lowest operating voltage?

Accepted Answer

A) SF6 circuit breaker 
B) Air break 
C) Air blast 
D) Minimum oil circuit breaker 
A) SF6 circuit breaker 
B) Air break 
C) Air blast 
D) Minimum oil circuit breaker

Question 8

What is switchgear?

Accepted Answer

A) An apparatus used for switching, controlling and protecting the electrical circuits and equipments. 
B) It detects the faults only. 
C) It corrects the faults only. 
D) All of the above. 
A) An apparatus used for switching, controlling and protecting the electrical circuits and equipments. 
B) It detects the faults only. 
C) It corrects the faults only. 
D) All of the above.

Question 9

Which among these are the main characteristics of a fuse element?

Accepted Answer

A) Low melting point 
B) High conductivity 
C) Least deterioration due to oxidation 
D) All of the above 
A) Low melting point 
B) High conductivity 
C) Least deterioration due to oxidation 
D) All of the above

Question 10

Which device sends the information to the circuit breaker to interrupt the circuit in case of fault?

Accepted Answer

A) Switch 
B) Relay 
C) Circuit breaker itself does this function. 
D) Fuse. 
A) Switch 
B) Relay 
C) Circuit breaker itself does this function. 
D) Fuse.

Question 11

Why is an isolator installed?

Accepted Answer

A) To isolate one portion of the circuit from another 
B) As an substitute for the circuit breaker 
C) It used on either sides of the circuit breaker 
D) Both (a) and (c) 
A) To isolate one portion of the circuit from another 
B) As an substitute for the circuit breaker 
C) It used on either sides of the circuit breaker 
D) Both (a) and (c)

Question 12

When does the circuit breaker operate in the line?

Accepted Answer

A) When power is to be supplie(
D)  
B) When the line is to be teste(
D)  
C) Whenever the fault occurs in the line. 
D) Whenever the switch and the relay has to be operate(
D)  
A) When power is to be supplie(
D)  
B) When the line is to be teste(
D)  
C) Whenever the fault occurs in the line. 
D) Whenever the switch and the relay has to be operate(
D)

Question 13

Plug setting of a electromagnetic relay can be altered by varying

Accepted Answer

A) Number of ampere turns 
B) Air gap of magnetic path 
C) Adjustable back stop 
D) None of these 
A) Number of ampere turns 
B) Air gap of magnetic path 
C) Adjustable back stop 
D) None of these

Question 14

What is the relation between the fusing current and the diameter of the wire?

Accepted Answer

A) I = k d3 
B) I = k d3/2 
C) I = k d2 
D) I = k d2/3 
A) I = k d3 
B) I = k d3/2 
C) I = k d2 
D) I = k d2/3

Question 15

What is the making capacity of the circuit breaker?

Accepted Answer

A) Less than the asymmetrical breaking capacity of the breaker 
B) Greater than the asymmetrical breaking capacity of the breaker 
C) Equal to the asymmetrical breaking capacity of the breaker 
D) Equal to the symmetrical breaking capacity of the breaker 
A) Less than the asymmetrical breaking capacity of the breaker 
B) Greater than the asymmetrical breaking capacity of the breaker 
C) Equal to the asymmetrical breaking capacity of the breaker 
D) Equal to the symmetrical breaking capacity of the breaker

Question 16

What is / are the main disadvantage / s of using oil as the quenching medium in the circuit breakers?

Accepted Answer

A) Need periodical replacement. 
B) Risk of formation of explosive mixture with air. 
C) Possibility of causing fire hazards. 
D) All of the above. 
A) Need periodical replacement. 
B) Risk of formation of explosive mixture with air. 
C) Possibility of causing fire hazards. 
D) All of the above.

Question 17

In a circuit breaker the contact space is ionised by what?

Accepted Answer

A) Field emission from the contact surface. 
B) Thermal emission from the contact surface. 
C) Thermal ionisation of gas. 
D) All of above. 
A) Field emission from the contact surface. 
B) Thermal emission from the contact surface. 
C) Thermal ionisation of gas. 
D) All of above.

Question 18

What should be the value of fusing factor?

Accepted Answer

A) Equal to zero 
B) Equal to one 
C) Less than one 
D) More than one 
A) Equal to zero 
B) Equal to one 
C) Less than one 
D) More than one

Question 19

Which circuit breaker is preferred to be installed in extra high voltage AC system?

Accepted Answer

A) Bulk oil type circuit breaker 
B) Air blast circuit breaker 
C) SF6 circuit breaker 
D) Vacuum circuit breaker 
A) Bulk oil type circuit breaker 
B) Air blast circuit breaker 
C) SF6 circuit breaker 
D) Vacuum circuit breaker

Question 20

A three phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3s. What is its symmetrical breaking current?

Accepted Answer

A) 1200 A 
B) 3600 A 
C) 35 kA 
D) 104.8 kA 
A) 1200 A 
B) 3600 A 
C) 35 kA 
D) 104.8 kA

What is the actuating quantity for the relays?

A fuse wire of circular cross section has a radius of 0.8mm. The wire blows off at a current of 9(A) What will be the radius of the wire that will blow off at a current of 1A?

Which among these tests are performed to check the nation or international standards?

The making and breaking currents of a 3 phase ac circuit breakers in power systems are respectively in ________form.

A three phase circuit breaker is rated 2000 MVA, 33 kV. What will be its making current?

Which of the following circuit breakers has the lowest operating voltage?

What is switchgear?

Which among these are the main characteristics of a fuse element?

Which device sends the information to the circuit breaker to interrupt the circuit in case of fault?

Why is an isolator installed?

When does the circuit breaker operate in the line?

Plug setting of a electromagnetic relay can be altered by varying

What is the relation between the fusing current and the diameter of the wire?

What is the making capacity of the circuit breaker?

What is / are the main disadvantage / s of using oil as the quenching medium in the circuit breakers?

In a circuit breaker the contact space is ionised by what?

What should be the value of fusing factor?

Which circuit breaker is preferred to be installed in extra high voltage AC system?

A three phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3s. What is its symmetrical breaking current?

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

Circuit Breakers and Fuses

Electric Arc and Circuit Breaker Protection

Electrical Protection and Switchgear

Relaying Schemes and Techniques for Electrical Equipment Protection

Understanding Relays for Power System Protection

Filters

Exam 9: Electrical Components and Circuit Breakers

What is the actuating quantity for the relays?

A fuse wire of circular cross section has a radius of 0.8mm. The wire blows off at a current of 9(A) What will be the radius of the wire that will blow off at a current of 1A?

Which among these tests are performed to check the nation or international standards?

The making and breaking currents of a 3 phase ac circuit breakers in power systems are respectively in ________form.

A three phase circuit breaker is rated 2000 MVA, 33 kV. What will be its making current?

Which of the following circuit breakers has the lowest operating voltage?

What is switchgear?

Which among these are the main characteristics of a fuse element?

Which device sends the information to the circuit breaker to interrupt the circuit in case of fault?

Why is an isolator installed?

When does the circuit breaker operate in the line?

Plug setting of a electromagnetic relay can be altered by varying

What is the relation between the fusing current and the diameter of the wire?

What is the making capacity of the circuit breaker?

What is / are the main disadvantage / s of using oil as the quenching medium in the circuit breakers?

In a circuit breaker the contact space is ionised by what?

What should be the value of fusing factor?

Which circuit breaker is preferred to be installed in extra high voltage AC system?

A three phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3s. What is its symmetrical breaking current?

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

Circuit Breakers and Fuses

Electric Arc and Circuit Breaker Protection

Electrical Protection and Switchgear

Relaying Schemes and Techniques for Electrical Equipment Protection

Understanding Relays for Power System Protection

Filters