MCQOPTIONS
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MCQOPTIONS
This section includes 715 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
By using which conductor is the skin effect reduced? |
| A. | Bundled conductors |
| B. | Stranded conductors |
| C. | Hollow conductors |
| D. | Solid conductors |
| Answer» C. Hollow conductors | |
| 152. |
Corona loss can be reduced by using 1. Solid conductor. 2. Hollow conductor. 3. Bundle conductor. |
| A. | 1 only |
| B. | 1 and 2 only |
| C. | 1, 2 and 3 only |
| D. | 2 and 3 only |
| Answer» E. | |
| 153. |
What is the cause of skin effect? |
| A. | Supply frequency |
| B. | Self inductance of conductor |
| C. | High sensitive material in the centre |
| D. | Both (a) and (b) |
| Answer» E. | |
| 154. |
Capacitance between the two conductors of a single phase two wire line is 0.5 μ F/km. What is the value of capacitance of each conductor to neutral? |
| A. | 0.5 μ F / km |
| B. | 1 μ F / km |
| C. | 0.25 μ F / km |
| D. | 2.0 μ F / km |
| Answer» C. 0.25 μ F / km | |
| 155. |
The conductor carries more current on the surface in comparison to its core. What is this phenomenon called? |
| A. | Corona |
| B. | Ferranti effect |
| C. | Skin effect |
| D. | Proximity effect |
| Answer» D. Proximity effect | |
| 156. |
Skin effect is negligible for what supply frequency and for what diameter? |
| A. | < 50 Hz and < 1 cm |
| B. | < 50 Hz and > 1 cm |
| C. | > 50 Hz and < 1 cm |
| D. | > 50 Hz and > 1 cm |
| Answer» B. < 50 Hz and > 1 cm | |
| 157. |
The inductance of a power transmission line increases with |
| A. | Decrease in line length |
| B. | Increase in diameter of conductor |
| C. | Increasing in spacing between the phase conductors |
| D. | Increase in load current carried by the conductors |
| Answer» D. Increase in load current carried by the conductors | |
| 158. |
The capacitance effect can be neglected in which among the transmission lines? |
| A. | Short transmission lines |
| B. | Medium transmission lines |
| C. | Long transmission lines |
| D. | All of these |
| Answer» B. Medium transmission lines | |
| 159. |
What is the value of capacitance to neutral for the two wire line? |
| A. | Twice the line to line capacitance |
| B. | Equal to line to line capacitance |
| C. | Thrice the line to line capacitance |
| D. | Half of line to line capacitance |
| Answer» B. Equal to line to line capacitance | |
| 160. |
The conductor of a 15 km long, single phase two wire line are separated by a distance of 1.5 m. The diameter of each conductor is 1 cm. If the conductors are of copper, the inductance of the circuit is |
| A. | 23.81 mH |
| B. | 35.72 mH |
| C. | 32.81 mH |
| D. | 53.72 mH |
| Answer» C. 32.81 mH | |
| 161. |
A single phase line has two parallel conductors 2 metre apart. The diameter of each conductor is 1.2 cm. What is the loop inductance per km of the line? |
| A. | 2.423 mH |
| B. | 1.234 mH |
| C. | 3.267 mH |
| D. | 8.632 mH |
| Answer» B. 1.234 mH | |
| 162. |
The inductance of a transmission line is minimum when_____________ |
| A. | GMD is high |
| B. | GMR is high |
| C. | Both GMD and GMR are high |
| D. | GMD is low and GMR is high |
| Answer» E. | |
| 163. |
Assertion (A): Transposition of conductors in a transmission line is necessary. Reason (R): Corona losses are reduced by transposition of conductors. |
| A. | Both A and R are true and R is the correct explanation of A |
| B. | Both A and R are true and R is not the explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» D. A is false but R is true | |
| 164. |
In case of stranded conductors, what is the ratio of the GMR to the actual radius? |
| A. | Equal to 1 |
| B. | More than 1 |
| C. | Equal to 0.7788 |
| D. | Less than 0.7788 |
| Answer» E. | |
| 165. |
Assertion (A): the concept of GMD is applicable for the calculation of inductance of transmission lines. Reason (R): The radius of the conductor of transmission lines, in the expression for inductance is not the self GMD of the conductor. |
| A. | Both A and R are true and R is the correct explanation of A |
| B. | Both A and R are true and R is not the explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 166. |
What happens in case of capacitance of line to ground, if the effect of earth is taken into account? |
| A. | Capacitance of line to ground decreases |
| B. | Capacitance of line to ground increases |
| C. | The capacitance remains unaltered |
| D. | The capacitance becomes infinite |
| Answer» C. The capacitance remains unaltered | |
| 167. |
On what concept is electrically short, medium and long lines based? |
| A. | Nominal voltage of the line |
| B. | Physical length of the line |
| C. | Wavelength of the line |
| D. | Power transmitted over the line |
| Answer» C. Wavelength of the line | |
| 168. |
In the modelling of short length overhead transmission line, why is the line capacitance to ground not considered? |
| A. | Equal to zero |
| B. | Finite but very small |
| C. | Finite but very large |
| D. | Infinite |
| Answer» C. Finite but very large | |
| 169. |
Why is the transmission lines transposed? |
| A. | Reduce corona loss |
| B. | Reduce skin effect |
| C. | Prevent interference with the neighbouring telephone lines |
| D. | Prevent short circuit between any two lines |
| Answer» D. Prevent short circuit between any two lines | |
| 170. |
If the double circuit 3 phase line has conductors of diameter 2 cm and distance of separation 2m in hexagonal spacing. What is the phase to neutral capacitance for 150 km of line? |
| A. | 2.4939 μ F |
| B. | 3.7408 μ F |
| C. | 1.8245 μ F |
| D. | 3.2548 μ F |
| Answer» C. 1.8245 μ F | |
| 171. |
A line of what length can be classified as a medium transmission line? |
| A. | 90 – 100 km |
| B. | 50 – 150 km |
| C. | 150 – 200 km |
| D. | Above 200 km |
| Answer» C. 150 – 200 km | |
| 172. |
A single phase transmission line of impedance j0.8 ohm supplies a resistive load of 500 A at 300 V. The sending end power factor is |
| A. | Unity |
| B. | 0.8 lagging |
| C. | 0.8 leading |
| D. | 0.6 lagging |
| Answer» E. | |
| 173. |
What will be the capacitance of a 100 km long, 3 phase, 50Hz overhead transmission line consisting of 3 conductors, each of 2 cm and spaced 2.5 m at the corners of an equilateral triangle? |
| A. | 1.007 μ F/phase |
| B. | 2.0075 μ F/phase |
| C. | 2.5 μ F/phase |
| D. | 1.45 μ F/phase |
| Answer» B. 2.0075 μ F/phase | |
| 174. |
A three phase, 50Hz transmission line consists of three equal conductors of radii ‘r’ placed in a horizontal plane with a spacing of 6m between middle and outer conductor. If the radius of each conductor is 12.5 mm, then inductance per phase per km of the transposed line will be |
| A. | 1.33 mH/km |
| B. | 1.65 mH/km |
| C. | 0.38 mH/km |
| D. | 2.145 mH/km |
| Answer» B. 1.65 mH/km | |
| 175. |
What are the values of A, B, C, D parameters of a short transmission line? |
| A. | Z, 0, 1, 1 |
| B. | 0, 1, 1, 1 |
| C. | 1, Z, 0, 1 |
| D. | 1, 1, Z, 0 |
| Answer» D. 1, 1, Z, 0 | |
| 176. |
For a transmission line which among the following relation is true? |
| A. | –AB + CD = 1 |
| B. | AD + BC = 1 |
| C. | AB – CD = -1 |
| D. | –AD + BC = 1 |
| Answer» E. | |
| 177. |
What happens if the separation between the three phases of the transmission line is increased? |
| A. | The inductance will increase and capacitance will remain unchanged. |
| B. | Both inductance and capacitance will decrease. |
| C. | Inductance will increase and capacitance will decrease. |
| D. | Inductance will decrease and capacitance will increase. |
| Answer» D. Inductance will decrease and capacitance will increase. | |
| 178. |
A two conductor single phase line operates at 50Hz. Diameter of each conductor is 20mm and the spacing between the conductors is 3m. The height of the conductors above the ground is 6m. What is the capacitance of the line to neutral? |
| A. | 9.7 pF/m. |
| B. | 10.8 pF/m. |
| C. | 3.57 pF/m. |
| D. | 2.415 pF/m. |
| Answer» B. 10.8 pF/m. | |
| 179. |
Why are bundled conductors employed? |
| A. | Appearance of the transmission line is improved |
| B. | Mechanical stability of the line is improved |
| C. | Improves current carrying capacity |
| D. | Improves the corona performance of the line |
| Answer» E. | |
| 180. |
Which harmonics are generated during the corona, which leads to the increase in corona losses? |
| A. | Third harmonics |
| B. | Fifth harmonics |
| C. | Seventh harmonics |
| D. | None of these |
| Answer» B. Fifth harmonics | |
| 181. |
Why is high voltage transmission lines transposed? |
| A. | Corona losses can be minimised |
| B. | Computation of inductance becomes easier |
| C. | Voltage drops in the lines can be minimised |
| D. | Phase voltage imbalances can be minimised |
| Answer» E. | |
| 182. |
When is the transposition of conductors in a transmission line done? |
| A. | When the conductors are not equally spaced |
| B. | When the conductors are spaced equilaterally |
| C. | When a telephone line runs parallel to the power line |
| D. | None of these |
| Answer» B. When the conductors are spaced equilaterally | |
| 183. |
A three phase transmission line has its conductors at the corners of an equilateral triangle with sides 3m. The diameter of each conductor is 1.63 cm. What is the inductance of the line per phase? |
| A. | 1.232 mH |
| B. | 1.184 mH |
| C. | 2.236 mH |
| D. | 2.68 mH |
| Answer» B. 1.184 mH | |
| 184. |
What will be the inductance of each conductor in a three phase, 3 wire system when they are arranged in a horizontal plane with spacing such that D31= 4m, D12 = D23 = 2m. The conductors are transposed and have a diameter of 2.5 cm. |
| A. | 2.22 mH |
| B. | 1.11 mH |
| C. | 3.33 mH |
| D. | 4.44 mH |
| Answer» C. 3.33 mH | |
| 185. |
What is the total resistance in a single phase or 2 – wire dc line? |
| A. | Equal to the resistance of either conductor |
| B. | Double the resistance of either conductor |
| C. | Half of the resistance of either conductor |
| D. | None of these |
| Answer» C. Half of the resistance of either conductor | |
| 186. |
Proximity effect is due to the current flowing in the ___________. |
| A. | Earth |
| B. | Sheath |
| C. | Nearby conductors |
| D. | All of these |
| Answer» D. All of these | |
| 187. |
Proximity effect |
| A. | Is more in large conductors, high frequency |
| B. | Increases the resistance of the conductor |
| C. | Reduces the self reactance |
| D. | All of these |
| Answer» E. | |
| 188. |
The current distribution may not be uniform in a conductor, which effect is this? |
| A. | Skin effect |
| B. | Proximity effect |
| C. | Ferranti effect |
| D. | None of these |
| Answer» C. Ferranti effect | |
| 189. |
Why are the hollow conductors used? |
| A. | Reduce the weight of copper |
| B. | Improve stability |
| C. | Reduce corona |
| D. | Increase power transmission capacity |
| Answer» D. Increase power transmission capacity | |
| 190. |
The inductance of a single phase two wire power transmission line per km gets doubled when |
| A. | Distance between the wires is doubled |
| B. | Distance between the wires increased fourfold |
| C. | Distance between the wires is increased as the square of the original distance |
| D. | Radius of the wire is doubled |
| Answer» D. Radius of the wire is doubled | |
| 191. |
Which of these given statements is wrong in consideration with bundled conductors? |
| A. | Control of voltage gradient |
| B. | Reduction in corona loss |
| C. | Reduction in the radio interference |
| D. | Increase in interference with communication lines |
| Answer» E. | |
| 192. |
Which tests are conducted to locate the fault location in the cables? |
| A. | Murray loop test |
| B. | Varley loop test |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» D. None of these | |
| 193. |
The effect of dirt on the surface of the conductor is to _____________ irregularity and thereby ________________ the break down voltage. |
| A. | Decreases, reduces |
| B. | Increases, increases |
| C. | Increases, reduces |
| D. | Decreases, increases |
| Answer» D. Decreases, increases | |
| 194. |
On what factor does the skin effect depend? |
| A. | Cross section of the conductors |
| B. | Supply frequency |
| C. | Permeability of the conductor |
| D. | All of these |
| Answer» E. | |
| 195. |
A 3 phase over head transmission line is supported by three discs of suspension insulators. The potentials across the first and second insulator are 8 and 11 kV respectively. What is the line voltage and string efficiency? |
| A. | 0.654 and 63.5% |
| B. | 0.375 and 68.3 % |
| C. | 0.527 and 56.34 % |
| D. | 0.287 and 65.258 % |
| Answer» C. 0.527 and 56.34 % | |
| 196. |
In case of dc voltage, smoother _____________ uniform glows near the positive conductor. |
| A. | Yellow |
| B. | Bluish white |
| C. | Reddish white |
| D. | Greenish yellow |
| Answer» C. Reddish white | |
| 197. |
The string efficiency of a high voltage line is around ______. |
| A. | 100 % |
| B. | 80 % |
| C. | 40 % |
| D. | 10 % |
| Answer» B. 80 % | |
| 198. |
Voltage across the string is ___________ times the line voltage. |
| A. | √3 |
| B. | √2 |
| C. | 1 / √3 |
| D. | 1 / √2 |
| Answer» B. √2 | |
| 199. |
What are the line constants in a transmission line? |
| A. | Resistance and series conductance only |
| B. | Series and shunt conductance |
| C. | Resistance, inductance and capacitance |
| D. | Resistance, inductance, capacitance and shunt conductance |
| Answer» E. | |
| 200. |
What is the value of energy distance in case of co-axial conductors? |
| A. | (r + 0.301 * √ r) |
| B. | (r + 0.308 * √ r) |
| C. | (r + 0.501 * √ r) |
| D. | (r + 0.508 * √ r) |
| Answer» C. (r + 0.501 * √ r) | |