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.
| 251. |
A single phase inductive load draws 10 MW at 0.6 power factor lagging. What is the value of the capacitor to be connected in parallel with the load to raise the power factor to 0.80?System voltage is 1000 V and system frequency is 50 Hz. |
| A. | 30 mF |
| B. | 40 mF |
| C. | 19 mF |
| D. | 23 mF |
| Answer» D. 23 mF | |
| 252. |
A single-phase line consists of two long solid conductors, each having a radius of r metre separated by a distance of D metre. What will be capacitance between the |
| A. | \(\frac{{0.121}}{{\log \left( {\frac{D}{r}} \right)}}\mu F/km\) |
| B. | \(\frac{{0.0121}}{{\log \left( {\frac{D}{r}} \right)}}\mu F/km\) |
| C. | \(\frac{{0.121}}{{\log \left( {\frac{r}{D}} \right)}}\mu F/km\) |
| D. | \(0.0121 \times \log \left( {\frac{D}{r}} \right)\mu F/km\) |
| Answer» C. \(\frac{{0.121}}{{\log \left( {\frac{r}{D}} \right)}}\mu F/km\) | |
| 253. |
It is always economical and desirable to improve the power factor of an installation in a power system to: |
| A. | Zero |
| B. | Unity |
| C. | Less than unity |
| D. | More than unity on the leading side |
| Answer» C. Less than unity | |
| 254. |
Improvement in power factor results in |
| A. | Change in kW |
| B. | Reduction in voltage |
| C. | Reduction in losses |
| D. | Change in frequency |
| Answer» D. Change in frequency | |
| 255. |
Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical? |
| A. | tatic condenser |
| B. | ynchronous condenser |
| C. | ap changing transformer |
| D. | ooster transformer |
| Answer» E. | |
| 256. |
For an ABCD parameter of a transmission line, which of the following is correct? |
| A. | AB – CD = 1 |
| B. | BD – AC = 1 |
| C. | AD – BC = 1 |
| D. | AD – BC = 0 |
| Answer» D. AD – BC = 0 | |
| 257. |
For a consumer, the most economical power factor is generally |
| A. | 0.5 lagging |
| B. | 0.95 lagging |
| C. | 0.4 leading |
| D. | 0.75 leading |
| Answer» C. 0.4 leading | |
| 258. |
Pmax is the maximum power that can be transferred through a transmission line, What is the maximum power transfer if a series capacitor with a degree of compensation \(k = \frac{1}{3}\) is connected in the line? |
| A. | 1.5 Pmax |
| B. | 3 Pmax |
| C. | \(\frac{2}{3}{P_{max}}\) |
| D. | \(\frac{1}{3}{P_{max}}\) |
| Answer» B. 3 Pmax | |
| 259. |
Maximum string efficiency is achieved when |
| A. | Uniform distribution of voltage across SCRs in a string appears |
| B. | Uneven voltage distribution of voltages across SCRs in a string appears |
| C. | One of the SCRs shares maximum voltage and rest share same voltage in a string |
| D. | Derating factor = 1-string efficiency |
| Answer» B. Uneven voltage distribution of voltages across SCRs in a string appears | |
| 260. |
In active power and frequency control,a. Frequency should remain constantb. A considerable drop in frequency could result in low magnetizing currents in induction motors and transformers.c. The frequency of a system is dependent on reactive power balance.d. Relatively closed control of frequency ensures constancy of the speed of induction motors.Which of the above statements are incorrect? |
| A. | a and b |
| B. | b and c |
| C. | c and d |
| D. | a and d |
| Answer» C. c and d | |
| 261. |
In nominal-π method of solution of medium transmission line, capacitance is assumed to be: |
| A. | assumed lumped at the sending end |
| B. | assumed lumped at the receiving end |
| C. | assumed lumped at the midpoint |
| D. | divided into two halves |
| Answer» E. | |
| 262. |
In design of underground cables the Mode of installation determines: |
| A. | Rating of cable to be used |
| B. | Type of cable to be used |
| C. | Size of cable to be used |
| D. | Temperature of cable to be used |
| Answer» C. Size of cable to be used | |
| 263. |
A lead sheath is used in an underground cable to |
| A. | Prevent ingress of moisture. |
| B. | Provide mechanical strength |
| C. | Provide adequate insulation |
| D. | Increase the capacitance to earth |
| Answer» B. Provide mechanical strength | |
| 264. |
For the transmission of a given amount of power, if the transmission voltage is increased, then the volume of conductor material required: |
| A. | remains the same |
| B. | decreases |
| C. | increases |
| D. | increases in proportion with the increase in voltage |
| Answer» C. increases | |
| 265. |
ACSR conductors have ________. |
| A. | all conductors made of aluminium |
| B. | outer conductors made of aluminum |
| C. | inner conductors made of aluminium |
| D. | no conductors made of aluminium |
| Answer» C. inner conductors made of aluminium | |
| 266. |
Consider the following statements: The calculation performed using short line approximate model instead of nominal-π model for a medium length transmission line delivering lagging load at a given receiving end voltage always results in higher:1. Sending end current2. Sending end power3. Regulation4. EfficiencyWhich of these statements are correct? |
| A. | 1 and 2 only |
| B. | 2 and 3 only |
| C. | 1, 2 and 4 |
| D. | 1, 2 and 3 |
| Answer» B. 2 and 3 only | |
| 267. |
In a 275 kV transmission line with line constants A = 0.85 ∠ 5° and B = 200 ∠75°, if the voltage profile at each end is to be maintained at 275 kV, the power at Unity Power Factor (UPF) will be nearly |
| A. | 98 MW |
| B. | 118 MW |
| C. | 144 MW |
| D. | 184 MW |
| Answer» C. 144 MW | |
| 268. |
______ voltages are caused by direct lightning strokes to the aerial lines in the high voltage system. |
| A. | Stray |
| B. | Surge |
| C. | Sag |
| D. | Stress |
| Answer» C. Sag | |
| 269. |
A 400 kV surge travels on an overhead line of surge impedance 400 Ω towards its junction with a cable which has a surge impedance of 40 Ω. What is the transmitted voltage? |
| A. | 36.36 kV |
| B. | 72.73 kV |
| C. | -327.27 kV |
| D. | 400 kV |
| Answer» C. -327.27 kV | |
| 270. |
For reducing tower footing resistance, it is better to use |
| A. | Chemical and ground rod only |
| B. | Chemical and counterpoise only |
| C. | Ground rod and counterpoise only |
| D. | None of these |
| Answer» D. None of these | |
| 271. |
In spite of some applications, cables are preferred over the transmission lines where |
| A. | Public safety is involved |
| B. | Scenic beauty of city is important |
| C. | Submarine crossing is there |
| D. | All of the above |
| Answer» E. | |
| 272. |
A network in which all the elements are physically separable is called a |
| A. | Distributive network |
| B. | Lumped network |
| C. | Passive network |
| D. | Reactive network |
| Answer» C. Passive network | |
| 273. |
______ wiring is used in residential, commercial and public buildings to improve appearance. |
| A. | Conduit |
| B. | Metal |
| C. | Cleat |
| D. | Batten |
| Answer» B. Metal | |
| 274. |
High voltage transmission lines use: |
| A. | Disc insulator |
| B. | Suspension insulator and Pin insulator |
| C. | Pin insulator |
| D. | Suspension insulator |
| Answer» E. | |
| 275. |
If voltage across the string is denoted by 'a' the number of discs on the string is denoted by 'b' and the voltage across disc nearest to the conductor is depicted by 'c' then the string efficiency is given by |
| A. | abc |
| B. | a / b |
| C. | a / (bc) |
| D. | (ab) / c |
| Answer» D. (ab) / c | |
| 276. |
_______ are merely convenient means of connecting switches and other equipment into the various arrangements at substations. |
| A. | Busbars |
| B. | Bus couplers |
| C. | Circuit breakers |
| D. | None of the above |
| Answer» B. Bus couplers | |
| 277. |
A 400 HP (300 kW), 3-phase 2400 V, 50 Hz star connected motor works at a lagging power factor of 0.7 and draws a current of 120.65 A. A bank of mesh connected condensers is used to raise power factor to 0.93 lagging. The efficiency of the motor is 85 %. The condensers available are of 600 V, 50 Hz rating. They are to be connected in delta to meet the requirement of power factor improvement. The capacitance of each capacitor is |
| A. | 54 μF |
| B. | 108 μF |
| C. | 162 μF |
| D. | 216 μF |
| Answer» B. 108 μF | |
| 278. |
In a string of suspension insulator, the maximum voltage appears across the unit |
| A. | Most far from the conductior |
| B. | Nearest to the conductor |
| C. | At the middle |
| D. | None of the above |
| Answer» C. At the middle | |
| 279. |
By using bundle conductors, the critical voltage for the formation of corona will be |
| A. | Remain same |
| B. | Increase |
| C. | Decrease |
| D. | Not occur |
| Answer» C. Decrease | |
| 280. |
Pole mounting substations are also known as: |
| A. | outdoor type |
| B. | indoor type |
| C. | open type |
| D. | basement type |
| Answer» B. indoor type | |
| 281. |
In protection of parallel feeders fed at one end: |
| A. | Both directional and non-directional can be used |
| B. | Either directional or non-directional can be used |
| C. | All the relays used are non-directional |
| D. | All the relays used are directional |
| Answer» B. Either directional or non-directional can be used | |
| 282. |
FACTS device is used for: |
| A. | enhancing controllability |
| B. | varying network impedance |
| C. | increasing power transfer |
| D. | all of the above |
| Answer» E. | |
| 283. |
In three – phase transmission lines, the exchange of conductor positions at regular intervals along the line is called _______. |
| A. | Termination |
| B. | Distribution |
| C. | Transposition |
| D. | Shunting |
| Answer» D. Shunting | |
| 284. |
No ceiling fan should be installed at height of less than |
| A. | 2.5 m from the floor |
| B. | 5.5 m from the floor |
| C. | 4.5 m from the floor |
| D. | 3.5 m from the floor |
| Answer» B. 5.5 m from the floor | |
| 285. |
Instantaneous characteristics of power system electromagnetic phenomena is given by typical duration of |
| A. | 3s – 1 min |
| B. | 30 cycles – 3s |
| C. | 0.5 – 30 cycles |
| D. | 50 ns – 1 ms |
| Answer» D. 50 ns – 1 ms | |
| 286. |
In a 2-wire system, the voltage at the supply end is constant at 500 V. The line is 3 km long. If the full-load current is 120 A, what must be the booster output so that the voltage at the other end is also 500 V. Take the resistance of the cable at the working temperature as 0.5 Ω/km. |
| A. | 2.16 kW |
| B. | 0.216 kW |
| C. | 21.6 kW |
| D. | 216 kW |
| Answer» D. 216 kW | |
| 287. |
_________ is a protective device which conducts the high voltage surges on the power system to the ground. |
| A. | Fuse |
| B. | Relay |
| C. | Circuit breaker |
| D. | Lightning arrester |
| Answer» E. | |
| 288. |
A 3-ϕ, 5 kW induction motor has a pf of 0.75 lagging. A bank of capacitors is connected in delta across the supply terminals, then p.f. is raised to 0.9 lagging. Determine the kVAr rating of the capacitors connected in each phase. |
| A. | 0.313 kVAr |
| B. | 0.256 kVAr |
| C. | 0.663 kVAr |
| D. | 0.113 kVAr |
| Answer» D. 0.113 kVAr | |
| 289. |
Corona loss is less when the shape of conductor is: |
| A. | Circular |
| B. | Flat |
| C. | Oval |
| D. | Independent of shape |
| Answer» B. Flat | |
| 290. |
Core is insulated by ________ in a belted cable: |
| A. | Impregnated paper |
| B. | VIR |
| C. | PVC |
| D. | Gutta Percha |
| Answer» B. VIR | |
| 291. |
Distribution substations are mostly _________. |
| A. | Indoor |
| B. | Submerged |
| C. | Pole mounted |
| D. | Floating |
| Answer» D. Floating | |
| 292. |
If, in a short transmission line, resistance and inductive reactance, are found to be equal and regulation appears to be Zero, then load will: |
| A. | Have unity power factor |
| B. | Have zero power factor |
| C. | Be 0.707 leading power factor |
| D. | be 0.707 lagging power factor |
| Answer» D. be 0.707 lagging power factor | |
| 293. |
A bushing, in which coaxial layers of metal foils are kept at floating potentials, is called |
| A. | condenser bushing |
| B. | impregnated bushing |
| C. | graded bushing |
| D. | non-linear bushing |
| Answer» B. impregnated bushing | |
| 294. |
An insulator is so designed that it should fail only by: |
| A. | a line breakdown |
| B. | a flash-over |
| C. | a puncture |
| D. | less sag |
| Answer» C. a puncture | |
| 295. |
Corona losses in DC transmission is: |
| A. | Minimum |
| B. | High |
| C. | Infinite |
| D. | Zero |
| Answer» B. High | |
| 296. |
If span length is doubled with no change in other factors, the sag of the line will become |
| A. | 2 times |
| B. | 0.5 time |
| C. | 4 times |
| D. | 8 times |
| Answer» D. 8 times | |
| 297. |
Power factor can be improved by installing a device in parallel with load which has _______. |
| A. | apparent power |
| B. | lagging reactive power |
| C. | resistive power |
| D. | leading reactive power |
| Answer» E. | |
| 298. |
In terms of A, B, C, D constants for short transmission line |
| A. | A = D = 1 |
| B. | B = D = 0 |
| C. | A = C = 1 |
| D. | C = D = 0 |
| Answer» B. B = D = 0 | |
| 299. |
In the transmission line, the voltage regulation is negative whenever receiving end voltage VR |
| A. | Half of the sending end voltage |
| B. | Greater than the sending end voltage |
| C. | Equal to the sending end voltage |
| D. | Less than the sending end voltage |
| Answer» C. Equal to the sending end voltage | |
| 300. |
Ferranti effect on long overhead lines is experienced when: |
| A. | Power factor is unity |
| B. | Line is lightly loaded |
| C. | Line is heavily loaded |
| D. | Line is fully loaded |
| Answer» C. Line is heavily loaded | |