McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 51. |
The most common way to calculate voltage sag is from ______ |
| A. | Average Voltage |
| B. | Peak Voltage |
| C. | RMS Voltage |
| D. | none of the above |
| Answer» C. RMS Voltage | |
| 52. |
Effect of temperature rise in overhead lines is to |
| A. | Increase Sag Decrease Tension |
| B. | Decrease Sag Increase Tension |
| C. | Increases both |
| D. | Decreases Both |
| Answer» A. Increase Sag Decrease Tension | |
| 53. |
What should be the value of sag for proper operation of overhead transmission line? |
| A. | High |
| B. | Low |
| C. | Neither too low nor too high |
| D. | Anything |
| Answer» C. Neither too low nor too high | |
| 54. |
Voltage dips cannot be caused by which of the following: |
| A. | Switching on of Large Loads |
| B. | Local and Remote faults |
| C. | Inductive Loading |
| D. | Capacitive Switching |
| Answer» D. Capacitive Switching | |
| 55. |
Which one of the following cannot be possible with voltage surges: |
| A. | Damaging to insulation |
| B. | Tripping of Sensitive Equipment |
| C. | Flicker in Incandescent Lamps |
| D. | Damage to electronic components |
| Answer» C. Flicker in Incandescent Lamps | |
| 56. |
During sag, power electronic component will trip, this will decrease ______ |
| A. | Load Voltage |
| B. | Supply Voltage |
| C. | Load Current |
| D. | none of the above |
| Answer» C. Load Current | |
| 57. |
The total power taken by the load remains constant so that _____ will be higher |
| A. | Current |
| B. | Voltage |
| C. | Fluctuations |
| D. | Harmonics |
| Answer» A. Current | |
| 58. |
The major cause of voltage sag is |
| A. | Malfunction of primary component |
| B. | Equipment Failure |
| C. | Starting of large Induction Machine |
| D. | All the above |
| Answer» D. All the above | |
| 59. |
To obtain a constant current input, a inductor is placed in current source inductor (CSI) in: |
| A. | Parallel |
| B. | Series |
| C. | Both Series and Parallel |
| D. | Not placed at all |
| Answer» B. Series | |
| 60. |
The harmonic current distortion in adjustable speed drive is_____ |
| A. | Constant |
| B. | Not Constant |
| C. | High |
| D. | low |
| Answer» B. Not Constant | |
| 61. |
Reducing the number of short-circuit faults in a system, reduces ______ |
| A. | Sag |
| B. | Interruptions |
| C. | Sag & Interruptions |
| D. | none of the above |
| Answer» C. Sag & Interruptions | |
| 62. |
Current-limiting fuses are able to clear a fault within one _______. |
| A. | Half cycle |
| B. | full cycle |
| C. | will not clear |
| D. | none of the above |
| Answer» A. Half cycle | |
| 63. |
By implementing changes in the supply system, the severity of the event will__. |
| A. | Reduce |
| B. | Increase |
| C. | Remains the same |
| D. | None of the above |
| Answer» A. Reduce | |
| 64. |
The main mitigation equipments is___ |
| A. | UPS |
| B. | Storage device |
| C. | voltage source converter |
| D. | All the above |
| Answer» D. All the above | |
| 65. |
During normal operation, the UPS takes its power from the supply, rectifies the ac voltage to dc and inverts it again to ac with the |
| A. | same frequency and rms value |
| B. | Different frequency and rms value |
| C. | same frequency and different rms value |
| D. | Different frequency and same rms value |
| Answer» A. same frequency and rms value | |
| 66. |
What is the value of transient stability limit? |
| A. | Higher than steady state stability limit |
| B. | Lower than steady state stability limit. |
| C. | Depending upon the severity of load |
| D. | All of these |
| Answer» B. Lower than steady state stability limit. | |
| 67. |
By using which component can the transient stability limit of a power system be improved? |
| A. | Series resistance |
| B. | Series capacitor |
| C. | Series inductor |
| D. | Shunt resistance |
| Answer» B. Series capacitor | |
| 68. |
What is transient stability limit? |
| A. | The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. |
| B. | The maximum power flow possible through a particular component connected in the power system. |
| C. | The maximum flow of power through a particular point in the power system without loss of stability when large and sudden disturbances occur |
| D. | All of these |
| Answer» C. The maximum flow of power through a particular point in the power system without loss of stability when large and sudden disturbances occur | |
| 69. |
Which among the following methods is used for improving the system stability? |
| A. | Increasing the system voltage |
| B. | Reducing the transfer reactance |
| C. | Using high speed circuit breaker |
| D. | All of these |
| Answer» D. All of these | |
| 70. |
What is steady state stability limit? |
| A. | The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. |
| B. | The maximum power flow possible through a particular component connected in the power system. |
| C. | The maximum flow of power through a particular point in the power system without loss of stability when sudden disturbances occur |
| D. | All of these |
| Answer» A. The maximum flow of power through a particular point in the power system without loss of stability when small disturbances occur. | |
| 71. |
Which among these is a classification of power system stability? |
| A. | Frequency stability |
| B. | Voltage stability |
| C. | Rotor angle stability |
| D. | All of these |
| Answer» D. All of these | |
| 72. |
The stability of the power system is not affected by which among these? |
| A. | Generator reactance |
| B. | Line losses |
| C. | Excitation of generators |
| D. | All of these |
| Answer» B. Line losses | |
| 73. |
What is power system stability? |
| A. | The maximum power flow possible through a particular component connected in the power system. |
| B. | The ability of the power system to regain the state of operating equilibrium point when the system is subjected to any disturbances. |
| C. | It is a phenomenon in which a power system losses its operating equilibrium when subjected to large disturbances. |
| D. | All of these |
| Answer» B. The ability of the power system to regain the state of operating equilibrium point when the system is subjected to any disturbances. | |
| 74. |
Power factor can be mathematically expressed as: |
| A. | P/Q |
| B. | Q/P |
| C. | P/S |
| D. | S/P |
| Answer» A. P/Q | |
| 75. |
The power factor angle of a purely inductive circuit is: |
| A. | 45 degree |
| B. | 60 degree |
| C. | 75 degrees |
| D. | 90 degree |
| Answer» D. 90 degree | |
| 76. |
In a load comprising of resistance and inductance: |
| A. | Load current lags voltage |
| B. | Load voltage lags current |
| C. | Both are in phase |
| D. | Any of above |
| Answer» A. Load current lags voltage | |
| 77. |
The power factor of capacitive circuits is: |
| A. | Leading |
| B. | Lagging |
| C. | Both of these |
| D. | Any of these |
| Answer» A. Leading | |
| 78. |
A circuit having poor power factor will draw: |
| A. | No current |
| B. | Low current |
| C. | Normal current |
| D. | High current |
| Answer» D. High current | |
| 79. |
The power factor of purely inductive circuits is: |
| A. | Leading |
| B. | Lagging |
| C. | Both of these |
| D. | Any of these |
| Answer» B. Lagging | |
| 80. |
A 500 kVA circuit drawing 200 kW and an inductive load requires how much capacitance to obtain unity power factor: |
| A. | 100 |
| B. | 200 |
| C. | 300 |
| D. | 400 |
| Answer» C. 300 | |
| 81. |
Which of the following statement refer to IEEE definition on power quality? |
| A. | The concept of powering of any electronic equipment in a manner suitable for the equipment. |
| B. | The concept grounding sensitive electronic equipment in a manner suitable for the equipment. |
| C. | The concept of grounding for whatever equipment in a manner suitable for the equipment. |
| D. | The concept of powering and grounding sensitive electronic equipment in a manner suitable for the equipment. |
| Answer» D. The concept of powering and grounding sensitive electronic equipment in a manner suitable for the equipment. | |
| 82. |
Which of the following explains the reasons for concern with power quality? |
| A. | End-user equipment become more sensitive to power quality due to many microprocessor-based controls |
| B. | The adjustable-speed motor drives helps to reduce harmonic levels |
| C. | Modern load & equipment are less sensitive to power quality variations. |
| D. | Power electronics equipment do not affect the power quality at all. |
| Answer» A. End-user equipment become more sensitive to power quality due to many microprocessor-based controls | |
| 83. |
The following statement describes the effects of poor power quality, EXCEPT |
| A. | Equipment malfunction |
| B. | Increased costs from downtime |
| C. | Premature failure of equipment |
| D. | Reduced maintenance, repair time and expenses |
| Answer» C. Premature failure of equipment | |
| 84. |
Since most of the industrial loads are inductive type, which of the following will help to correct the power factor? |
| A. | Increase lagging reactive current demand of the loads |
| B. | Compensate lagging reactive current by supplying leading reactive current to the power system |
| C. | Compensate leading reactive current by supplying lagging reactive current to the power system |
| D. | Reduce leading reactive current demand of the loads |
| Answer» B. Compensate lagging reactive current by supplying leading reactive current to the power system | |
| 85. |
Which of the following is an advantages of power factor correction (PFC)? |
| A. | Electricity bills increased |
| B. | Power consumption reduced |
| C. | Increased heating in equipment |
| D. | Extra kVAr availability from the supply |
| Answer» B. Power consumption reduced | |
| 86. |
Which of the following represents short duration voltage variation? |
| A. | Under Voltage |
| B. | Over Voltage |
| C. | Voltage Outage |
| D. | Voltage Interference |
| Answer» C. Voltage Outage | |
| 87. |
Which of the following terms describes the transient voltage variation? |
| A. | The duration is within 0.5 s to 30 cycles |
| B. | It can be classify to instantaneous, momentary or temporary |
| C. | It can be solved by using static Var systems |
| D. | It can be caused by lightning, electrostatic discharge or load switching. |
| Answer» D. It can be caused by lightning, electrostatic discharge or load switching. | |
| 88. |
Which of the following terms describes the effects of harmonics to industrial power systems? |
| A. | Disturbance to Electric and Electronic Devices |
| B. | Extra Fault Current |
| C. | Lower Losses |
| D. | Increased costs from downtime |
| Answer» A. Disturbance to Electric and Electronic Devices | |
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