McqMate
| 1. |
Non-sinusoidal waveforms are made of |
| A. | different sinusoidal waveforms |
| B. | fundamental and even harmonics |
| C. | fundamental and odd harmonics |
| D. | even and odd harmonics only |
| Answer» A. different sinusoidal waveforms | |
| 2. |
The positive and negative halves of a complex wave are symmetrical when |
| A. | it contains even harmonics |
| B. | phase difference between even harmonics and fundamentals is 0 or it |
| C. | it contains odd harmonics |
| D. | phase difference between even harmonics and fundamental is either n/2 or 3n/2 |
| Answer» C. it contains odd harmonics | |
| 3. |
The rms value of the complex voltage given by v = 161i sin cot + 12 Ari sin Rot is |
| A. | 20 Ari |
| B. | 20 |
| C. | 28 |
| D. | 192 |
| Answer» B. 20 | |
| 4. |
In a 3-phase system,the harmonic has negative phase sequence of RBY. |
| A. | 9 |
| B. | 13 |
| C. | 5 |
| D. | 15 |
| Answer» C. 5 | |
| 5. |
Two complex waves will have the same wave-shape if |
| A. | they contain the same harmonics |
| B. | ratio of corresponding harmonics to their respective fundamentals is the same |
| C. | harmonics are similarly spaced with respect to their fundamental |
| D. | they have all of the above |
| Answer» D. they have all of the above | |
| 6. |
The trigonometric Fourier series for a complex wave will contain positive cosine terms only when |
| A. | it contains even harmonics |
| B. | its two half-cycles are symmetrical |
| C. | its value is zero at 0= n/2, 3n/2 etc. |
| D. | its value is zero at 0= n, 2n etc. |
| Answer» C. its value is zero at 0= n/2, 3n/2 etc. | |
| 7. |
Tansient disturbance is produced in a circuit whenever |
| A. | it is suddenly connected or discon nected from the supply |
| B. | it is shorted |
| C. | its applied voltage is changed suddenly |
| D. | all of the above |
| Answer» D. all of the above | |
| 8. |
There are no transients in pure resistive circuits because they |
| A. | offer high resistance |
| B. | obey Ohm's law |
| C. | have no stored energy |
| D. | are linear circuits |
| Answer» C. have no stored energy | |
| 9. |
Transient current in electrical circuits are associated with |
| A. | inductors |
| B. | capacitors |
| C. | resistors |
| D. | both (a) and (b) |
| Answer» D. both (a) and (b) | |
| 10. |
The transients which are produced due to sudden but energetic changes from one steady state of a circuit to another are called transients. |
| A. | initiation |
| B. | transition |
| C. | relaxation |
| D. | subsidence |
| Answer» B. transition | |
| 11. |
In an R-L circuit connected to an alternating sinusoidal voltage, size of transient current primarily depends on |
| A. | the instant in the voltage cycle at which circuit is closed |
| B. | the peak value of the steady-state current |
| C. | the circuit impedance |
| D. | the voltage frequency |
| Answer» A. the instant in the voltage cycle at which circuit is closed | |
| 12. |
Double-energy transients are produced in circuits consisting of |
| A. | two or more resistors |
| B. | resistance and inductance |
| C. | resistance and capacitance |
| D. | resistance, inductance and capacitance |
| Answer» D. resistance, inductance and capacitance | |
| 13. |
The transient current in a loss-free L-C circuit when excited from an ac source is a/an sine wave. |
| A. | over-damped |
| B. | undamped |
| C. | under-damped |
| D. | critically damped |
| Answer» B. undamped | |
| 14. |
Transient current in an R-L-C circuit is oscillatory when |
| A. | R =0 |
| B. | R> 2f-17 |
| C. | R <2 |
| D. | R =2 |
| Answer» C. R <2 | |
| 15. |
For measuring positive, negative and zero sequence voltages in a system, the reference is taken as : |
| A. | Neutral of the system only |
| B. | Ground only |
| C. | For zero sequence neutral and for positive and negative the ground |
| D. | None of the above |
| Answer» D. None of the above | |
| 16. |
The most economic load on an underground cable is : |
| A. | Greater than its surge loading |
| B. | Less thart the surge loading |
| C. | Equal to the surge loading |
| D. | None of the above is necessary |
| Answer» B. Less thart the surge loading | |
| 17. |
In case of a 3-phase short circuit is a system, the power fed into the system is : |
| A. | Mostly reactive |
| B. | Mostly active |
| C. | Active and reactive both equal |
| D. | Reactive only |
| Answer» A. Mostly reactive | |
| 18. |
An RLC series circuit remains predominantly inductive : |
| A. | At resonance frequency |
| B. | Below resonance frequency |
| C. | Above resonance frequency |
| D. | At the lower half power frequency |
| Answer» C. Above resonance frequency | |
| 19. |
A generator is connected to a synchronous motor. From stability point of view it is preferable to have : |
| A. | Generator neutral reactance grounded and motor neutral resistance grounded |
| B. | Generator and motor neutrals resistance grounded |
| C. | Generator and motor neutrals reactance grounded |
| D. | Generator neutral resistance and motor neutral reactace grounded |
| Answer» D. Generator neutral resistance and motor neutral reactace grounded | |
| 20. |
The positive sequency component of voltage at the point of fault is zero when it is a : |
| A. | 3-phase fault |
| B. | L-L fault |
| C. | L-L-G fault |
| D. | L-G fault |
| Answer» C. L-L-G fault | |
| 21. |
Tick out the correct statement : |
| A. | The negative and zero sequence voltages are maximum at the fault point and decreases towards the neutral |
| B. | The negative and zero sequence voltages are minimum at the fault point and increase towards the neutral |
| C. | The negative sequence is maximum and zero sequence minimum at the fault point and decrease and increase respectively towards the neutral. |
| D. | None of the above |
| Answer» D. None of the above | |
| 22. |
The order of the lightning discharge current is : |
| A. | 10,000 amp |
| B. | 100 amp |
| C. | 1 amp |
| D. | 1 microampere |
| Answer» A. 10,000 amp | |
| 23. |
The magnetising-inrush-current in a transformer is rich in : |
| A. | 3rd harmonics |
| B. | 5th harmonics |
| C. | 7th harmonics |
| D. | 2nd harmonics |
| Answer» C. 7th harmonics | |
| 24. |
The in-rush current of a transformer at no load is maximum if the supply voltage is switched on |
| A. | At zero voltage value |
| B. | At peak voltage value |
| C. | At V/2 value |
| D. | At ,6 /2V value |
| Answer» A. At zero voltage value | |
| 25. |
Pure inductive circuit takes power (reactive) from the a.c. line when |
| A. | both applied voltage and current rise |
| B. | both applied voltage and current decrease |
| C. | applied voltage decreases but current increases |
| D. | (a) and (b) |
| Answer» C. applied voltage decreases but current increases | |
| 26. |
With 100% series compensation of lines |
| A. | the circuit is series resonant at power frequency |
| B. | low transient voltage |
| C. | high transient current |
| D. | (a) and (b) |
| Answer» D. (a) and (b) | |
| 27. |
In a pure LC parallel circuit under resonance condition, current drawn from the supply mains is |
| A. | very large |
| B. | V ,FTE |
| C. | V /11-j |
| D. | Zero |
| Answer» D. Zero | |
| 28. |
A lightning arrestor connected between the line and earth in a power system |
| A. | protects the terminal equipment against travelling surges |
| B. | protects the transmission line against lightning stroke |
| C. | suppresses high frequency oscillations in the line |
| D. | reflects back the travelling wave approaching it |
| Answer» A. protects the terminal equipment against travelling surges | |
| 29. |
Lightning arresters are used in power systems to protect electrical equipments against |
| A. | direct strokes of lightning |
| B. | power frequency overvoltages |
| C. | overvoltages due to indirect lightning stroke |
| D. | overcurrents due to lightning stroke |
| Answer» A. direct strokes of lightning | |
| 30. |
Consider the following statements : The transient stability of the power system under unbalanced fault conditions can be effectively improved by
|
| A. | 1 and 2 are correct |
| B. | 2 and 3 are correct |
| C. | 3 and 4 are correct |
| D. | 1 and 3 are correct |
| Answer» C. 3 and 4 are correct | |
| 31. |
One current transformer (CT) is mounted over a 3-phase 3-core cable with its sheath and armour removed from the portion covered by the CT. An ammeter placed in the CT secondary would measure |
| A. | the positive sequence current |
| B. | the negative sequence current |
| C. | the zero sequence current |
| D. | three times the zero sequence |
| Answer» D. three times the zero sequence | |
| 32. |
Earth wire on EHV overhead transmission line is provided to protect the line against |
| A. | lightning surge |
| B. | switching surge |
| C. | excessive fault voltages |
| D. | corona effect |
| Answer» A. lightning surge | |
| 33. |
The velocity of travelling wave through a cable of relative permittivity 9 is |
| A. | 9 x 108 m/s |
| B. | 3 x 108 m/s |
| C. | 108 m/s |
| D. | 2 x 108 ms |
| Answer» C. 108 m/s | |
| 34. |
A wave-trap is used at the termination of a HVAC overhead line to a station switchyard to |
| A. | prevent the transformer magnetising harritonics from reaching the overhead line |
| B. | damp the incoming surge waves from the overhead lines |
| C. | attenuate sub-harmonic oscillations |
| D. | provide for carrier communication |
| Answer» D. provide for carrier communication | |
| 35. |
Shunt compensation in an EHV line is used to improve |
| A. | stability and fault level |
| B. | fault level and voltage profile |
| C. | voltage profile and stability |
| D. | stability, fault level and voltage profile |
| Answer» B. fault level and voltage profile | |
| 36. |
The principal information obtained from load flow studies in a power system are
|
| A. | I and 2 |
| B. | 3 and 4 |
| C. | 1,2 and 3 |
| D. | 2 and 4 |
| Answer» C. 1,2 and 3 | |
| 37. |
While rising and while falling, if a wave is symmetrical, it contains |
| A. | even harmonics in addition to fundamental |
| B. | odd harmonics in addition to fundamental |
| C. | (b) both odd and even harmonics in addition to fundamental |
| D. | none of the above |
| Answer» B. odd harmonics in addition to fundamental | |
| 38. |
While rising and falling if a wave is not symmetrical, it contains |
| A. | even harmonics in addition to fundamental |
| B. | odd harmonics in addition to fundamental |
| C. | both odd and even harmonics in additions to fundamental |
| D. | none of the above |
| Answer» A. even harmonics in addition to fundamental | |
| 39. |
The main reason for generation of harmonics in a transformer could be |
| A. | fluctuating load |
| B. | poor insulation |
| C. | mechanical vibrations |
| D. | saturation of core |
| Answer» D. saturation of core | |
| 40. |
Harmonics in transformer result in |
| A. | increased core losses |
| B. | increased 12R losses |
| C. | magnetic interference with communication circuits |
| D. | all of the above |
| Answer» D. all of the above | |
| 41. |
Which fractional pitch will eliminate the seventh harmonic from the voltage waveform of an alternator? |
| A. | 6/7 |
| B. | 7/8 |
| C. | 5/6 |
| D. | None of the above |
| Answer» A. 6/7 | |
| 42. |
Most of the power quality problems are related to ______ |
| A. | Transmission Issue |
| B. | Grounding Issue |
| C. | Distribution Issue |
| D. | all of the above |
| Answer» B. Grounding Issue | |
| 43. |
Which of the following is not considered as good power quality voltage |
| A. | Power Supply is more compared to demand |
| B. | Constant sine wave |
| C. | Constant Velocity |
| D. | Constant RMS Value unchanged with time |
| Answer» A. Power Supply is more compared to demand | |
| 44. |
Lightening and Tree striking on a live conductor is an example________ Power Quality issue. |
| A. | Voltage Sag |
| B. | Voltage Swell |
| C. | Interruption |
| D. | Surge |
| Answer» B. Voltage Swell | |
| 45. |
Interruption is |
| A. | complete loss of power |
| B. | complete loss of voltage |
| C. | complete loss of current |
| D. | all the above |
| Answer» B. complete loss of voltage | |
| 46. |
The Transients in the power system occurs for |
| A. | less than two complete cycles |
| B. | exact two complete cycles |
| C. | less than one complete cycles |
| D. | exact one complete cycles |
| Answer» C. less than one complete cycles | |
| 47. |
The most common cause of long interruption is ______ |
| A. | Faults |
| B. | Outages |
| C. | Both (a) & (b) |
| D. | none of the above |
| Answer» C. Both (a) & (b) | |
| 48. |
Outage is the |
| A. | Removal of Primary Component |
| B. | (b) No Power Generation |
| C. | Transmission Faults |
| D. | (d) None of the above |
| Answer» A. Removal of Primary Component | |
| 49. |
Single Phase Tripping is generally used in _________________. |
| A. | Transmission System |
| B. | Distribution System |
| C. | Low Voltage System |
| D. | Generation System |
| Answer» A. Transmission System | |
| 50. |
The Short Interruptions occurs for |
| A. | Less than two complete cycles |
| B. | exact two complete cycles |
| C. | less than one complete cycles |
| D. | exact one complete cycles |
| Answer» C. less than one complete cycles | |
| 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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