MCQ Questions on Transmission & Distribution

301. Property of absorbing moisture from atmosphere is

(a) Solubility
(b) Viscosity
(c) Porosity
(d) Hydroscopicity

302. Conduit pipes are normally used to protect ……… cables.

(a) unsheathed cables
(b) armoured
(c) PVC sheathed cables
(d) all of these

303. In the case of three core flexible cable, the colour of the neutral is

(a) Black
(b) Blue
(c) Brown
(d) Green

304. Which among the following cable are generally suited for the voltage up to 11 kV?

(a) Belted cables
(b) Screened cables
(c) Pressure cables
(d) None of these

305. What is the voltage rating of extra high tension underground cable?

(a) 33 kV to 66 KV
(b) 22 kV to 33 kV
(c) 11 kV
(d) 132 kV

306. A cable has inductance of 0.22 mH per kilometer and capacitance of 0.202 μF per kilometer. The surge impedance of the cable is

(a) 50 Ω
(b) 42 Ω
(c) 33 Ω
(d) 28 Ω

307. Talking about the cable insulating materials the temperature and voltage resisting capacity is the least in the case of

(a) VIR
(b) Gutta Percha
(c) Rubber
(d) PVC

308. The insulation resistance of a cable of length 10 km is 1 Mega ohm. Its resistance for 50 km length will be………

(a) 1 Mega ohm
(b) 5 Mega ohm
(c) 0.2 Mega ohm
(d) 50 Mega ohm

309. The effect of bonding the cables is to

(a) increase effective resistance and inductance
(b) increase effective resistance but reduce inductance
(c) decrease effective resistance and inductance
(d) decrease effective resistance but increase inductance

310. Which of the following may not be the possible reason for open circuit fault in the cable ?

(a) due to rupture of electric insulation
(b) due to excessive pressure
(c) due to breaking of core of cable
(d) due to swift turn

311. In comparison to overhead transmission, in underground systems

(a) Voltage drop is less
(b) Fault correction is easier
(c) Value of charging current is less
(d) Initial cost of the system is low

312. ………. is done just above bedding’s surface.

(a) Metallic Sheathing
(b) Serving
(c) Insulation
(d) Armouring

313. Length of the cable is doubled, its capacitance C will be

(a) One-fourth
(b) Half
(c) Doubled
(d) None of the above

314. The advantage of the Varle loop test over Murray loop test is:

(a) Can be used for localizing the short circuit fault
(b) Loop resistance can be determined
(c) Can be used for localizing the earth fault
(d) Their accuracy is higher

315. When localizing ground fault with the help of a loop test, the resistance of a fault

(a) Affects the balance condition
(b) Affect the value of the cable resistance
(c) Affects the sensitivity of the bridge
(d) All of these

316. If ‘r’ is the radius of the conductor and ‘R’ the radius of the sheath of the cable. The cable operates stably from the view point of dielectric strength is

(a) r/R > 1.0
(b) r/R < 1.0
(c) r/R < 0.632
(d) r/R <0.368

317. The leakage resistance of a 50 km long cable is 1 MΩ. For a 100 km long cable it will be

(a) 1 ΜΩ
(b) 2 ΜΩ
(c) 0.66 ΜΩ
(d) 0.5 ΜΩ

318. The characteristic impedance of a cable is about

(a) 300 Ω
(b) 50 Ω
(c) 5 Ω
(d) 2 Ω

319. A piece of co-axial cable has a 75Ω characteristic impedance and a nominal capacitance of 69 pF/m. What is the inductance per meter ?

(a) 0.388 H/m
(b) 3.88 μH/m
(c) 38.88 μH/m
(d) 0.388 μH/m

320. Murry, 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

321. Which of the following test is carried out to ensure the sufficient strength of insulation between two or more conductor to avoid leakage between them?

(a) Testing of insulation resistance between wire and earth
(b) Testing of insulation resistance between conductor
(c) Testing of polarity of single phase switch
(d) Testing of earth continuity path

322. Values of the ABCD constants for short line are given by

(a) A = Z, B = 1, C = 0, D = 1
(b) A = 1, B = 1, C = Z, D =1
(c) A = 1, B = Z, C = 0, D =1
(d) A =1, B =1, C = 0, D = Z

323. Factor of safety is the ratio of

(a) Permissible stress / Ultimate stress
(b) Ultimate stress / Working stress
(c) Permissible stress / Ultimate strain
(d) Ultimate strain / permissible strain

324. A DC two-wire distributor system suppliers a constant load. What is the saving in copper, if the voltage is doubled with power transmitted remaining the same?

(a) 25 %
(b) 50 %
(c) 75 %
(d) 25% increased

325. In a two end fed equal voltage and balanced D.C. distribution supply, where is the minimum voltage produces

(a) load point where both side current meet
(b) middle point
(c) load point from where maximum current is drawn
(d) between one side end and mid point

326. The percentage ratio of copper for 3-wire DC system to 2-wire DC distribution system for same cross-section of neutral wire as outer wire is

(a) 40.5 %
(b) 40.6%
(c) 31.25%
(d) 37.5%

327. In radial distribution system the distributor is fed

(a) from both end
(b) from the centre
(c) from one end
(d) at different point

328. A radial power system is represented by

(a) Closed paths
(b) Closed and open paths
(c) Only open paths
(d) None of above

329. The main criterion for the design of distributor is

(a) The voltage drop
(b) Corona loss
(c) Temperature rise
(d) Radio interference

330. Which of the following DC link is not used in HVDC transmission?

(a) Monopolar
(b) Bipolar
(c) Homopolar
(d) Heteropolar

331. The voltage that has been selected for HVDC transmission.

(a) ± 500 kV
(b) ± 550 kV
(c) ± 600 kV
(d) ± 300 kV

332. Consider the following Statements.

Statement A: Electricity is distributed from a single point in a radial distribution system.
Statement B: There are less fluctuation in supply at the consumer’s terminal.
Which of the following is correct?
(a) A and B are true and B is the correct explanation of A
(b) B is true but A is false.
(c) A is true but B is false
(d) A and B are true but B is not the correct explanation of A.

333. Which of the following is connected in series with the feeder ?

(a) Conductor
(b) Distribution transformer
(c) Booster
(d) Earth Connection

334. Radial system is used when

(a) energy is to be produced on high potential
(b) energy is to be produced on low potential
(c) sub station is far away from load station
(d) number of consumers are more

335. When ring feeder distributes energy from two or more generation plants, then this distribution system is known as

(a) Radial system
(b) Ring main system
(c) Interconnected system
(d) Underground system

336. For the stable operation of an interconnected system, which passive element can be used as interconnecting element ?

(a) Resistor
(b) Relay
(c) Capacitor
(d) Reactor

337. A line which connects a distributor to substation is called

(a) Distributor
(b) Feeder
(c) Line
(d) Service main

338. In a power system, active power control is related to

(a) both voltage and frequency control
(b) frequency control
(c) voltage control
(d) steam control

339. A single phase, 3 wire AC system is made up of

(a) 3 conductor wires
(b) 1 conductor wire and 2 neutral
(c) 1 conductor wire and 1 neutral
(d) 2 conductor wire and I neutral

340. For consumer which power factor is economical

(a) 0.95 lagging
(b) 0.4 leading
(c) 0.75 leading
(d) 0.5 lagging

341. A 3-4 balanced system working at 0.9 lagging power factor has a line loss of 3600 kW. If p.f. is reduced to 0.6 the line loss would be

(a) 8100 kW
(b) 1600 kW
(c) 5400 kW
(d) 2400 kW

342. Power factor can be improved by

(a) Synchronous machine
(b) STATCOM
(c) Static VAR Compensator
(d) All of above

343. The maximum value of power factor is

(a) 0.5
(b) 1
(c) 1.5
(d) 2.0

344. Stepping up of voltage during transmission is done to

(a) increase efficient power transfer
(b) maximum power transfer
(c) reduce transmission losses
(d) reduce voltage drop

345. Which of the following is used for power factor improvement in transmission line?

(a) Three phase induction
(b) An overexcited three phase synchronous motor running on no load
(c) Three phase AC series motor
(d) Choke

346. Counterpoise is used for

(a) Transformer earthing
(b) Reducing transmission tower footing resistance
(c) Generator earthing
(d) Motor earthing

347. Three phase step-up transformer installed at power house, just before commencement of transmission line, have

(a) DELTA-DELTA connection
(b) STAR-STAR connections
(c) STAR-DELTA connections
(d) DELTA-STAR connections

348. Booster transformers are used to

(a) To change the voltage magnitude and phase angle
(b) Reduce the voltage magnitude
(c) Increase the voltage magnitude
(d) To change the voltage phase angle

349. A synchronous compensator is a synchronous motor running

(a) Without a mechanical load and variable excitation
(b) Without a mechanical load and fixed excitation
(c) With a mechanical load and fixed excitation
(d) With a mechanical load and variable excitation

350. Which type of connection in 3 phase transformer is used at the substation end of the transmission line

(a) Star-Star
(b) Star-Delta
(c) Delta-Delta
(d) Delta-Star

351. Booster Transformers are used in

(a) Transmission systems
(b) Both transmission and distribution system
(c) Distribution systems
(d) Neither transmission nor distribution systems

352. Y-Δ connected transformer satisfactorily works for

(a) only unbalanced load
(b) neither balanced or unbalanced load
(c) only balanced load
(d) both balanced and unbalanced load

353. Match the transmission lines given in Column A with their respective voltage carrying capacity in column B.

Column-A

1. Primary Transmission
2. Primary Distribution
3. Secondary Transmission
4. Secondary Distribution

Column-B

1. 132 kV
2. 66 kV
3. 33 KV
4. 400 V

(a) 1-b; 2-a; 3-c; 4-d
(b) 1-d; 2-c; 3-b; 4-a
(c) 1a; 2-c; 3-b; 4-d
(d) 1a; 2b; 3-d; 4-c

354. The power factor of which of the following circuit is unity?

1. Pure Inductive
2. Pure Capacitive
3. Pure Resistive

(a) 1 and 2 only
(b) only 3
(c) only 1
(d) 1, 2 and 3

355. What is the value of reflection coefficient for a short circuit line?

(a) 1
(c) -1
(b) 0
(d) 0.5

356. For power factor improvement the amount of capacitance required for star connected capacitor bank is

(a) Three times less than delta connected banks
(b) Half of the delta connected banks
(c) Equal to delta connected banks
(d) Three times more than delta connected banks