MCQOPTIONS
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MCQOPTIONS
This section includes 517 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
A single core cable used on a 3.3 kV, 50 Hz system has conductor diameter 10 mm and internal diameter of sheath 25 mm. Permittivity of insulator of sheath, k = 3.5, power factor of an open circuit is 0.03. The capacitance of cable per km will be |
| A. | 0.212 μF |
| B. | 0.414 μF |
| C. | 0.667 μF |
| D. | 0.512 μF |
| Answer» B. 0.414 μF | |
| 152. |
For a transmission line supported at different elevations at the two ends, the tension is maximum at the |
| A. | shorter support |
| B. | taller support |
| C. | mid point |
| D. | horizontal point on the line |
| Answer» C. mid point | |
| 153. |
A 300 km long overhead transmission line having inductance of 1.25 mH/km and capacitance of 5 nF/km terminates at a load impedance of 2 kΩ. When a surge voltage of 100 kV is applied to the transmission line, the voltage reflected back from the load is |
| A. | 10 kV |
| B. | 30 kV |
| C. | 60 kV |
| D. | 100 kV |
| Answer» D. 100 kV | |
| 154. |
Load frequency control is achieved by properly matching the individual machine’s |
| A. | reactive power |
| B. | generated voltages |
| C. | turbine inputs |
| D. | turbine and generator ratings |
| Answer» D. turbine and generator ratings | |
| 155. |
A single-phase transmission line consists of two parallel conductors one meter apart and 1.25 cm in diameter. The loop inductance per km of the line is: |
| A. | 21.3 × 10-4 Henry/ km |
| B. | 34.3 × 10-7 Henry/ km |
| C. | 11.5 × 10-7 Henry/ km |
| D. | 19.5 × 10-7 Henry/ km |
| Answer» B. 34.3 × 10-7 Henry/ km | |
| 156. |
If d is the diameter of an overhead transmission line conductor and t is the thickness of the ice covered over it then, the overall diameter of the ice-covered conductor becomes: |
| A. | D = d + 3t |
| B. | D = d + 4t |
| C. | D = d + t |
| D. | D = d + 2t |
| Answer» E. | |
| 157. |
According to grid standard regulation by Central Electricity Authority (CEA), the maximum permissible value of voltage unbalance for a 220 kV line is: |
| A. | 2% |
| B. | 1.5% |
| C. | 4% |
| D. | 3% |
| Answer» B. 1.5% | |
| 158. |
In any case, where the height of transmission tower is increased |
| A. | the line to ground capacitance and inductance will not change |
| B. | the line to line capacitance and inductance will decrease |
| C. | the line to line capacitance will decrease and line inductance will increase |
| D. | the line to ground capacitance will decrease but line inductance remain unchanged |
| Answer» E. | |
| 159. |
A pair of high-frequency parallel transmission lines has distributed capacitance and inductance of 0.8 μF and 9.8 mH respectively. What is the characteristic impedance of the line? |
| A. | 98.26 Ω |
| B. | 110.68 Ω |
| C. | 125 Ω |
| D. | 128.2 Ω |
| Answer» C. 125 Ω | |
| 160. |
Consider the below points:i) Minimum size of cable ii) Voltage dropiii) Current carrying capacityiv) Type of insulation used Which of the above constitute specifications that need be considered while selecting wires? |
| A. | (I), (ii), (iii) and (iv) |
| B. | (iv) and (ii) |
| C. | (ii), (iii) and (iv) |
| D. | (i), (ii) and (iii) |
| Answer» B. (iv) and (ii) | |
| 161. |
For a 66 kV line having a span of 200 meters between towers, the approximate sag will be |
| A. | 0.02 m |
| B. | 0.3 m |
| C. | 2 m |
| D. | 20 m |
| Answer» D. 20 m | |
| 162. |
Power transmission for long distance is carried out at: |
| A. | High voltage |
| B. | Low voltage |
| C. | Low current |
| D. | High current |
| Answer» B. Low voltage | |
| 163. |
A commonly used polyphase system in India is: |
| A. | Three phase |
| B. | Two phase |
| C. | Single phase |
| D. | Six phase |
| Answer» B. Two phase | |
| 164. |
Power transmission lines are transposed to reduce |
| A. | Skin effect |
| B. | Ferranti effect |
| C. | Transmission loss |
| D. | Interference with neighboring communication lines |
| Answer» E. | |
| 165. |
In a dc two-wire feeder, the voltage drop is 4%. What will be the transmission capacity of the feeder? |
| A. | 96% |
| B. | 94% |
| C. | 92% |
| D. | 98% |
| Answer» D. 98% | |
| 166. |
Pin type insulators are used for transmission lines |
| A. | Up to 33 kV |
| B. | Above 33 kV |
| C. | Below 33 kV |
| D. | of 400 kV and above |
| Answer» B. Above 33 kV | |
| 167. |
A transmission line of \(50{\rm{\;\Omega }}\) characteristic impedance is terminated with a \(\rm 100 \ Ω\) resistance. The minimum impedance measured on the line is equal to |
| A. | 0 Ω |
| B. | 25 Ω |
| C. | 50 Ω |
| D. | 100 Ω |
| Answer» C. 50 Ω | |
| 168. |
On a Power grid the Load is generally |
| A. | Capacitive |
| B. | Resistive |
| C. | Inductive |
| D. | All of these |
| Answer» D. All of these | |
| 169. |
Identify the graph shown in the given figure. |
| A. | Sag chart |
| B. | Stringing chart |
| C. | Corona chart |
| D. | Tension chart |
| Answer» C. Corona chart | |
| 170. |
_________ is supported from the ceilings. |
| A. | Belt conveyor |
| B. | Roller conveyor |
| C. | Chain conveyor |
| D. | Trolly conveyor |
| Answer» E. | |
| 171. |
As per recommendation of ISI the maximum number of points of lights, fans and socket outlets that can be connected in one sub circuit is |
| A. | 8 |
| B. | 10 |
| C. | 15 |
| D. | 20 |
| Answer» C. 15 | |
| 172. |
______ voltages can be available from a 3 wire DC distribution system. |
| A. | One |
| B. | Four |
| C. | Two |
| D. | Three |
| Answer» D. Three | |
| 173. |
In a string of suspension insulators, if potential across each disc is same then its string efficiency is: |
| A. | 50% |
| B. | 100% |
| C. | Less than 100% |
| D. | More than 100% |
| Answer» C. Less than 100% | |
| 174. |
If the number of poles in a 3-ϕ 11 kV transmission line is 80, then how many disc insulators are required? |
| A. | 240 |
| B. | 80 |
| C. | 6 |
| D. | 160 |
| Answer» B. 80 | |
| 175. |
An alternator is supplying a load of 400 kW at pf of 0.8 lagging. If the power factor is raised to unity, how many more kilowatts can alternator supply for the same kVA Loading? |
| A. | 400 kW |
| B. | 200 kW |
| C. | 500 kW |
| D. | 100 kW |
| Answer» E. | |
| 176. |
Peterson coil is also known as |
| A. | Shunt compensation coil |
| B. | Tapping coil |
| C. | Arc suppression coil |
| D. | None of the above |
| Answer» D. None of the above | |
| 177. |
In an HVDC transmission, the DC output voltage can be controlled to get inverter operation when the firing angle is |
| A. | α = 0° |
| B. | 0° < α < 90° |
| C. | 90° < α < 180° |
| D. | 0°< α <180° |
| Answer» D. 0°< α <180° | |
| 178. |
In transmission lines the cross-arms are made of ________. |
| A. | Wood |
| B. | Steel |
| C. | RCC |
| D. | Copper |
| Answer» C. RCC | |
| 179. |
Cable impregnation means application of ______ compound on the paper used in cables. |
| A. | non-insulating oil |
| B. | insulating oil |
| C. | insulating metal |
| D. | non-insulating metal |
| Answer» C. insulating metal | |
| 180. |
Murray, Varley and Fisher loop tests are used for |
| A. | short circuit fault in cables |
| B. | open circuit fault in the cables |
| C. | short circuit and ground fault in cables |
| D. | open circuit and ground fault in cables |
| Answer» D. open circuit and ground fault in cables | |
| 181. |
For transmission line which one of the following relations is true? |
| A. | AD – BC = 1 |
| B. | –AD – BC = 1 |
| C. | AD – BC = -1 |
| D. | AD – BC = 0 |
| Answer» B. –AD – BC = 1 | |
| 182. |
A two bus power system shown in the figure supplies load of 1.0 + j 0.5 p.u.The values of V1 in p.u. and δ2 respectively are |
| A. | 0.95 and 6.00° |
| B. | 1.05 and -5.44° |
| C. | 1.1 and -6.00° |
| D. | 1.1 and -27.12° |
| Answer» C. 1.1 and -6.00° | |
| 183. |
A single-phase motor takes 50 A at a power factor angle of 30° lagging from a 250-V, 50-Hz AC supply. What value of capacitance must a shunting capacitor have to raise the power factor to unity? |
| A. | 212.3 μF |
| B. | 838.6 μF |
| C. | 636.6 μF |
| D. | 318.3 μF |
| Answer» E. | |
| 184. |
For increasing the limit of distance of transmission line, |
| A. | Series resistance are used |
| B. | Synchronous condensers are used |
| C. | Series capacitors and shunt reactors are used |
| D. | Shunt capacitors and shunt reactors are used |
| Answer» D. Shunt capacitors and shunt reactors are used | |
| 185. |
66 kV is suitable for transmission of power over _________. |
| A. | 30 km |
| B. | 60 km |
| C. | 120 km |
| D. | 200 km |
| Answer» C. 120 km | |
| 186. |
If the length of the cross-arm of the tower is increased, then what is the net effect on the string efficiency? |
| A. | Increases |
| B. | No change |
| C. | Zero |
| D. | Decreases |
| Answer» B. No change | |
| 187. |
/**//**/Directions: For the Assertion (A) and Reason (R) below, choose the correct alternative:Assertion (A): 3 wire dc distribution system is preferred over 2 wire dc distribution system.Reason (R): the 3 wire dc system of distribution is safer. |
| A. | Both A and R are true and R is not the explanation of A |
| B. | Both A and R are true and R is the correct explanation of A |
| C. | None of these |
| D. | A is true but R is false |
| Answer» E. | |
| 188. |
DC current flowing through a conductor: |
| A. | Distributes non-uniformly over the cross-section |
| B. | Concentrates towards the centre |
| C. | Concentrates towards the outer periphery |
| D. | Distributes uniformly over the cross-section |
| Answer» E. | |
| 189. |
Consider the following types of transmission lines:1. Open-wire line2. Twin-lead wire3. Coaxial cableThe capacitance per metre will be least in which of the above transmission lines? |
| A. | 1 only |
| B. | 2 only |
| C. | 3 only |
| D. | 1, 2 and 3 |
| Answer» B. 2 only | |
| 190. |
In 3 wire DC system, the area of cross section of neutral is generally _________ of either outer. |
| A. | 1/4th |
| B. | Half |
| C. | Same |
| D. | Doubled |
| Answer» C. Same | |
| 191. |
In a 3-wire DC transmission system, if the potential difference is 460 V, then the potential difference of positive outer above the neutral will be: |
| A. | 230 V |
| B. | 115 V |
| C. | -115 V |
| D. | 460 V |
| Answer» B. 115 V | |
| 192. |
For transmission and distribution of electrical power, which one of the following materials is NOT used? |
| A. | Copper |
| B. | Tungsten |
| C. | Steel |
| D. | Aluminium |
| Answer» C. Steel | |
| 193. |
In overhead transmission lines, the maximum length of span for RCC poles should be ______ meters. |
| A. | 200 - 400 meters |
| B. | 80 - 100 meters |
| C. | 30 - 70 meters |
| D. | 10 - 20 meters |
| Answer» C. 30 - 70 meters | |
| 194. |
An overhead transmission line has a span of 220 meters, conductor weighing 804 kg/km. Calculate the maximum SAG if the ultimate tensile strength of the conductor is 5758 kg. Assume safety factor as 2. Also find maximum tension T. |
| A. | SAG = 1.69, T = 2879 kg |
| B. | SAG = 2, T = 2800 kg |
| C. | SAG = 2.21, T = 2875 kg |
| D. | SAG = 1.89, T = 2789 kg |
| Answer» B. SAG = 2, T = 2800 kg | |
| 195. |
In EHV and UHV system, the type of surge diverter used for overvoltage protection is |
| A. | Value type DiC arresters |
| B. | Gapless ZnO arresters |
| C. | Gapless SiC arresters |
| D. | Rod gap arresters |
| Answer» C. Gapless SiC arresters | |
| 196. |
One 750 kV line can normally carry as much power as how many 400 kV circuits for equal distance of transmission? |
| A. | 3 |
| B. | 2 |
| C. | 4 |
| D. | 1 |
| Answer» D. 1 | |
| 197. |
Ferranti effect states that under certain conditions, the sending end voltage is |
| A. | Less than receiving end voltage |
| B. | Greater than receiving end voltage |
| C. | Equal to receiving end voltage |
| D. | Not having any impact on the receiving end voltage |
| Answer» B. Greater than receiving end voltage | |
| 198. |
Corona effect is observed in |
| A. | Underground cables |
| B. | Underwater cables |
| C. | Overhead distribution lines |
| D. | Overhead EHV transmission lines |
| Answer» E. | |
| 199. |
Find the approximate value of sag for a 66 kV line which has a span of 200 m between towers. |
| A. | 0.02 m |
| B. | 2 m |
| C. | 0.2 m |
| D. | 20 m |
| Answer» C. 0.2 m | |
| 200. |
In a string of 2 suspension insulators, each unit has a self capacitance X and a pin to earth, capacitance 0.1 X. If the maximum voltage across any unit is not to exceed 12.1 kV, the insulator string can withstand a maximum voltage of |
| A. | 11 kV |
| B. | 13.2 kV |
| C. | 23.1 kV |
| D. | 33 kV |
| Answer» D. 33 kV | |