MCQOPTIONS
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MCQOPTIONS
This section includes 239 Mcqs, each offering curated multiple-choice questions to sharpen your Dairy Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
The transient current in a loss-free L-C circuit when excited from an ac source isa/an sine wave. |
| A. | over-damped |
| B. | undamped |
| C. | under-damped |
| D. | critically damped |
| Answer» C. under-damped | |
| 152. |
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» B. Constant sine wave | |
| 153. |
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» B. Mostly active | |
| 154. |
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» D. phase difference between even harmonics and fundamental is either n/2 or 3n/2 | |
| 155. |
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» E. | |
| 156. |
Most of the power quality problems are related to ______ |
| A. | Transmission Issue |
| B. | Grounding Issue |
| C. | Distribution Issue |
| D. | all of the above |
| Answer» C. Distribution Issue | |
| 157. |
The power factor of capacitive circuits is: |
| A. | Leading |
| B. | Lagging |
| C. | Both of these |
| D. | Any of these |
| Answer» B. Lagging | |
| 158. |
Interruption is |
| A. | complete loss of power |
| B. | complete loss of voltage |
| C. | complete loss of current |
| D. | all the above |
| Answer» C. complete loss of current | |
| 159. |
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» E. | |
| 160. |
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» E. | |
| 161. |
In a 3-phase system,the harmonic has negative phase sequence of RBY. |
| A. | 9 |
| B. | 13 |
| C. | 5 |
| D. | 15 |
| Answer» D. 15 | |
| 162. |
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» B. Increase | |
| 163. |
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» D. exact one complete cycles | |
| 164. |
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» B. the peak value of the steady-state current | |
| 165. |
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» D. none of the above | |
| 166. |
The total power taken by the load remains constant so that _____ will be higher |
| A. | Current |
| B. | Voltage |
| C. | Fluctuations |
| D. | Harmonics |
| Answer» B. Voltage | |
| 167. |
Outage is the |
| A. | Removal of Primary Component |
| B. | (b) No Power Generation |
| C. | Transmission Faults |
| D. | (d) None of the above |
| Answer» B. (b) No Power Generation | |
| 168. |
The most common cause of long interruption is ______ |
| A. | Faults |
| B. | Outages |
| C. | Both (a) & (b) |
| D. | none of the above |
| Answer» D. none of the above | |
| 169. |
The trigonometric Fourier series for a complex wave will contain positive cosineterms 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» D. its value is zero at 0= n, 2n etc. | |
| 170. |
The power factor of purely inductive circuits is: |
| A. | Leading |
| B. | Lagging |
| C. | Both of these |
| D. | Any of these |
| Answer» C. Both of these | |
| 171. |
The magnetising-inrush-current in a transformer is rich in : |
| A. | 3rd harmonics |
| B. | 5th harmonics |
| C. | 7th harmonics |
| D. | 2nd harmonics |
| Answer» D. 2nd harmonics | |
| 172. |
During normal operation, the UPS takes its power from the supply, rectifies the acvoltage 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» B. Different frequency and rms value | |
| 173. |
A circuit having poor power factor will draw: |
| A. | No current |
| B. | Low current |
| C. | Normal current |
| D. | High current |
| Answer» E. | |
| 174. |
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» D. 400 | |
| 175. |
The main mitigation equipments is___ |
| A. | UPS |
| B. | Storage device |
| C. | voltage source converter |
| D. | All the above |
| Answer» E. | |
| 176. |
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» E. | |
| 177. |
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» E. | |
| 178. |
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» B. Decrease Sag Increase Tension | |
| 179. |
Which of the following represents short duration voltage variation? |
| A. | Under Voltage |
| B. | Over Voltage |
| C. | Voltage Outage |
| D. | Voltage Interference |
| Answer» D. Voltage Interference | |
| 180. |
Transient current in electrical circuits are associated with |
| A. | inductors |
| B. | capacitors |
| C. | resistors |
| D. | both (a) and (b) |
| Answer» E. | |
| 181. |
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» C. Series inductor | |
| 182. |
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» C. Depending upon the severity of load | |
| 183. |
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» E. | |
| 184. |
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» B. 7/8 | |
| 185. |
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» D. none of the above | |
| 186. |
Power factor can be mathematically expressed as: |
| A. | P/Q |
| B. | Q/P |
| C. | P/S |
| D. | S/P |
| Answer» B. Q/P | |
| 187. |
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» E. | |
| 188. |
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» E. | |
| 189. |
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» B. full cycle | |
| 190. |
Reducing the number of short-circuit faults in a system, reduces ______ |
| A. | Sag |
| B. | Interruptions |
| C. | Sag & Interruptions |
| D. | none of the above |
| Answer» D. none of the above | |
| 191. |
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» E. | |
| 192. |
The order of the lightning discharge current is : |
| A. | 10,000 amp |
| B. | 100 amp |
| C. | 1 amp |
| D. | 1 microampere |
| Answer» B. 100 amp | |
| 193. |
The principal information obtained from load flow studies in a power system are 1. magnitude and phase angle of the voltage at each bus. 2. reactive and real power flows in each of lines. 3. total power loss in the network. 4. Transient stability limit of the system Select the correct answer from the codes given below : |
| A. | I and 2 |
| B. | 3 and 4 |
| C. | 1,2 and 3 |
| D. | 2 and 4 |
| Answer» D. 2 and 4 | |
| 194. |
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» D. Damage to electronic components | |
| 195. |
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» B. power frequency overvoltages | |
| 196. |
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» C. Increased heating in equipment | |
| 197. |
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» D. L-G fault | |
| 198. |
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» C. (b) both odd and even harmonics in addition to fundamental | |
| 199. |
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» E. | |
| 200. |
Earth wire on EHV overhead transmission line is provided to protect the lineagainst |
| A. | lightning surge |
| B. | switching surge |
| C. | excessive fault voltages |
| D. | corona effect |
| Answer» B. switching surge | |