# Power System Protection Multiple Choice Questions

In this article, you will find the power system protection multiple choice questions and answers for electrical, and electronics engineers.

## Power System Protection Multiple Choice Questions

The below list provides all the objective questions and answers related to electrical power systems.

Answers are available at the bottom of the article.

1. Phase Directional Overcurrent Relay with 90-degree connection – MTA is 45 degrees at phase A.​

The relay will signal trip, when the phase A phase Tripping zone has an angle

2. Phase Directional Overcurrent Relay with 60-degree connection, when considering only relays at Phase A, which quantity is Operating and which quantity is Polarizing respectively

3. One relay reactance has the function according to the equation y = 4.5​

If a transmission line has a total impedance of 4 + j4 ohms, assuming that the fault at the end of the transmission line and The arc resistance is 0.5 ohm.​ What is the response of the relay?

4. Which type of relay is suitable for detecting Faults in high-voltage power transmission systems?

5. Which of the following are the impedance relay properties of the impedance relay?

6. Analysis of the operation of the relay.​

The distance is generally used which diagram?

7. Setting the distance relay, Step Distance Protection, Relay Zone 3, will have to set the delay time to work at the estimated time.

8. How does Power System Swing affect distance relays?

9. Which is not the Directional Overcurrent Relay working condition?

10. Setting the distance relay, Step Distance Protection, Relay Zone 2 will have to set

11. Protection of high voltage power lines using a three-zone protection distance relay.​ If you want to avoid potential errors, you need to adjust the distance.​

Zone 3 does not exceed any of the following values

12. Standard Inverse Overcurrent Relay is compatible with CT Ratio = 1000/5 A, Pick Up Value = 5 A, TMS = 0.1​

When the Fault Current is 15 times the Relay Setting, how long does it work?

13. Input signal to distance relay

14. When distance relay works?

15. The Radial System distribution system, as shown, requires both relays to have a Standard Inverse (SI) operation curve according to IEC 60255.​

If the relay at Bus B is set to be done Work as backup protection for the relay at Bus A, with a margin of time = 0.35 seconds.​

Ask how much TMS of the relay B must be adjusted at Bus B

The image was available in the quiz file.

16. “Quadrilateral Relay” is a suitable relay for use in which manner of protection.

17. Over current relays with Extremely Inverse (EI) operation, fault current is 5,000 A.​

CT Ratio is 800/5, current setting or PSM is 125%, If you want the relay to operates at 2.0 seconds, how much TMS value should be adjusted?

18. Over current relays with Standard Inverse (SI) Curve operation, Fault current is 4,000 A.​

If you want the relay to operate at 1.5 seconds, CT Ratio is 800/5, current value setting is 100%, what will be the TMS setting?

19. One of the impedance relays has a circular motion.​

A radius of 10 ohms has a central point at the origin.​

Used together with the reactance relays that have the function according to the condition of the equation y – 8 = 0, at the intersection between the lines, the behavior of both relays have R of

20. What is distance relay’s Overreach?

21. Phase Directional Overcurrent Relay with 90-degree connection when considering only relays at Phase A, which quantity is Operating and which quantity is Polarizing respectively

22. Which is the feature of the Impedance Relay?

23. Impedance Relay is suitable for preventing short-circuits between the phase of transmission lines of which length

24. Which distance relay is suitable for the protection of power lines that have a very long cable length?

25. How does the fault resistance caused by arc affect Distance Relay?

26. Over current relays with Very Inverse operation (VI) [IEC 60255] by setting TMS to 0.6 if using CT Ratio 600/5 A and adjusting the current to 100%, the fault current is equal to 4,000 A.​

Calculate how much time the relay needs to operate?

27. Setting the distance relay, Step Distance Protection, Relay Zone 1 should be set to protect the transmission line in the approximate distance

28. Phase directional overcurrent relay of 90-degree connection type – 45 degree MTA.​

At maximum torque, the power factor is

29. What are the characteristics of over current relays? Popular today

30. Which of the following relays Arranged in the Distance Relays group

31. The Radial System distribution system, as shown, requires both relays Curves are Extremely Inverse (EI) operation [IEC 60255].​

If the relay at Bus B is set to Back up protection of the relay at Bus A using the difference of working time (Grading Margin) equal to 0.35 seconds when the Fault occurs within the Primary Zone (F2) of the relay of Bus B itself, then How much time the relay at Bus B will require to pick up.

The image was available in the quiz file.

32. The transmission line size 2.5 + j3.5 ohm must set the value of the impedance relay to the maximum value.​

Therefore, able to protect the LTC ARC Fault with the size of 1.0 ohms

33. Very Inverse Overcurrent Relay has the following settings:​

Time Multiplier Setting (TMS) = 0.3, CT Ratio = 1000/1 A by setting the current to 100%, if the Fault current 10,000 A.​

Calculate how much time the relay needs to operate?

34. Setting the distance relay, Step Distance Protection, Relay Zone 1, what is the working time setting?

35. Electromechanical phase directional overcurrent relay type 90-degree connection – 45-degree MTA.​

Angle between Operating Quantity and Polarizing, what is the maximum amount of torque generated?

36. Which terms describe the meaning of the device “CCVT” correctly

37. Which distance relay is suitable for the protection of power lines that have a very long cable length?

38. High-voltage power lines have an impedance per phase of 1 + j10 ohms/phase.​

Determine how much the size and angle of impedance respectively are.

39. The impedance value is the value that the distance relay sees when knowing the CT Ratio and VT Ratio values must be multiplied by any multiplier.

40. Relay The distance to be used to protect the transmission line has a CT Ratio = 1000/5 A and VT Ratio = 115 kV / 110 V.​

What is the multiplier value for adjusting the relay operation?

41. What is the feature of the Mho Relay feature?

42. One of the impedance relays has a circular motion, with a radius of 4 ohms.​

The center is at the origin.​

When connected with a directional relay (Directional Relay) that has the characteristics According to the equation y = -x, what is the impedance value appears where the relay will not work.

43. Current transformer (CT) with coordinate size, Burden 15 VA, test rate 200/5 A Accuracy Class 10 P 20, What is the value of composite error?

44. In the Ground Fault Distance Relay setting for protection, when a single line to ground fault (SLG) occurs, which parameters must be considered

45. Which of the following relays is arranged in the Distance Relays group

46. The setting for Phase Fault Distance Relay must use which Sequence Impedance to adjust the settings for the relay.

47. “Lenticular Relay” has the following features:

48. Impedance Relay is suitable for preventing short-circuit between the phase of transmission lines of any length

49. Using distance relay (Distance Relay) to protect power lines Why the zone of protections be divided into sections?

50. Which of the following concerns the transmission line protection using Distance Relay?

51. Protection of Earth Fault Protection in a 3-phase power system with Residual Connected method.​

Where current transformer (CT) is required?

52. Ground Directional Overcurrent Relay can use Which quantity to make a “Polarizing Signal” to let the relay know the direction.

53. What is the secondary standard Voltage of Voltage transformer: VT that is currently in use?

54. The Radial System distribution system, as shown, requires both relays have an Extremely Inverse (EI) function [IEC 60255] if the relay is adjusted as specified in the figure, Discrimination Between the relays at Bus A and the relay at Bus B using Grading Margin = 0.35 seconds, how much is the TMS of the relay B at Bus B

The image was available in the quiz file.

55. Overcurrent Relay has a Curve of Long Time Inverse (LTI) in accordance with IEC 60255, where the PSM = 5 and TMS = 1, relays will work for 30 seconds.​

Let the relay work with 3.0 seconds at the same PMS value.​

What is the TMS value?

56. Discrimination What is the current overload protection system?

57. Ground Directional Overcurrent Relay, when Single Line to Ground Faults occur. polarization voltage is

58. Phase Directional Overcurrent Relay Type Electromechanical type 90-degree Connection – 30-degree MTA.​

What is the maximum torque that the Power Factor angle?

59. Which of the following relay Is the main relay used to protect the three-phase high-voltage power transmission line (Step Three Zone Protection)

60. Using distance relay (Distance Relay) to protect power lines Why must the zone of protections be divided into sections?

61. In High voltage power transmission protection, in general what type of relay is used to protect

62. Over current relays have a Standard Inverse operation (SI) [IEC 60255] with a TMS setting of 0.5​

If using the CT Ratio 800/5 A and adjusting the current to 100%, The fault current is equal to 5,000 A.​

Calculate how much time the relay needs to operate?

63. Which of the following distance relays is with features of direction?

64. Setting the distance relay, Step Distance Protection, Relay Zone 1 should be set to protect the transmission line in the approximate distance

65. What are the properties of Vacuum Circuit Breaker?

66. “Rated Burden” of the current transformer (CT) means

67. Why do we use Distance Relay to protect high voltage power lines?

68. “CCVT” stands for what

69. Over current relays Extremely Inverse (EI) [IEC 60255] by setting TMS to 0.5 if using CT Ratio 1200/5 A and adjusting the current to 100% When the fault occurs and the value is equal to 7,000 A.​

What will be the tripping time?

70. What is Distance Relay Reach?

71. Which is not a protective system?

72. Faults on the overhead line in a 3-phase system, which has the highest frequency of occurrence

73. Standard Inverse Overcurrent Relay connected to the current transformer (CT) with Current Ratio of 1000/1 A, TMS = 0.1, adjusted to 125% if the current size of the fault occurs 5,000 A, relay operating time is

74. What is the feature of the Mho Relay feature?

75. One line of transmission is 80 km long with the impedance Z = 0.03 + j 0.21 Ohm / km.​

What is the admittance of this transmission line?

76. How does the Power System Swing affect the distance relay?

77. Extremely Inverse Overcurrent Relay is set as follows:​

Time Multiplier Setting (TMS) = 0.2, CT Ratio = 1000/5 A, Pick Up Value = 4 A. Fault = 8,000 A.​

Calculate how much time relay need to works?

78. Which is not the function of the current transformer (CT)?

79. The high-voltage power line has an impedance per phase of 10 ohms, a 70-degree angle.​

If you want to protect the transmission line, you can get 80% of the entire line length.​

Adjustable impedance value, what is the setting

80. Which of the above mentioned “Faults” in the electrical system is wrong from reality?

81. Reducing the risk of underreach of distance relay Can be solved by

82. What are “Instrument Transformers”?

83. What are the characteristics of the Mho Relay distance relay function on the R-X diagram mode?

84. Which of the following distance relays is with features of no direction?

85. Which is not the characteristic of faults in the power system?

86. Current transformer transformers (CT), the size of the Burden 15 VA with a flow rate of 200/5 A Accuracy Class 10 P 20, Accuracy Limit Factor (ALF) is how much?

87. If you want to make Earth Fault Protection with Overcurrent Relay, the Relay Number is

88. Reactance Relay (Reactance Relay) is a distance relay that will work when

89. What are the features of SF6 Circuit Breaker?

90. One transmission line has an impedance including a line of 6 + j8 ohms.​

When each Fault occurs, there is very little arc resistance so it can be ignored.​

If the impedance relay is set to look like Working in a circle, a radius of 8 ohms with a center point at the origin The relay can prevent the Fault from thinking about how many percent of the total transmission line length.

91. Standard Inverse Overcurrent Relay connected to the current transformer (CT) with Current Ratio of 1000/5 A, TMS = 0.2, set at 100% if the current size is caused 5,000 A, relay operating time is

92. Setting the distance relay, Step Distance Protection, Relay Zone 1, what is the working time setting?

93. The distance Relay to be used to protect the transmission line has a CT Ratio = 1000/5 A and VT Ratio = 115 kV / 110 V.​

What is the multiplier value for adjusting the relay operation?

94. Radial distribution system as shown below Requiring both relays have a standard operation Inverse (SI) [IEC 60255].​

Discrimination Between relays at Bus A and at Bus B using Grading Margin = 0.35 seconds and adjust the settings as specified to calculate the time that the relay at Bus B runs when the Fault occurs as shown

The image was available in the quiz file.

95. How to use the Residual Current as a Polarizing Signal to detect the direction of the Ground Faults. What should I do?

96. Standard secondary current of current transformer For the current protection system, what is the standard value?

97. When the Arc Fault occurs in the power transmission line The operation of any of the following relays has the least risk of underreach problems.

98. Which type of relay is suitable for detecting Faults in high voltage power transmission systems?

99. Setting the distance relay, Step Distance Protection, Relay Zone 3, will have to set

100. Setting the distance relay, Step Distance Protection, Relay Zone 2 should be set to protect the transmission line in the approximate distance