MCQ Questions on Transmission & Distribution

200. When two conductors each of radius ‘r’ are at a distance ‘D’, the capacitance between the two is proportional to

(a) log_e(D/r)
(b) log_e(r/D)
(c) 1 ÷ log_e(D/r)
(d) 1 ÷ log_e(r/D)

201. As the voltage of transmission increases, the volume of conductor

(a) Increase
(b) does not change
(c) decrease
(d) increases proportionately [MP JE – 2016]

202. If diameter of each conductor of a transmission line is ‘d’, then the conductor will be diameter of n-layer stranded

(a) (2n-1)d
(b) (2n + 1)d
(c) (3n-1)d
(d) (3n+ 1)d

203. If we represent the conductor diameter by ‘d’, skin effect will be proportional to

(a) d
(b) √d
(c) d²
 (d) d³ [UPPCL – 2016]

204. To increase power transfer capability of a long transmission line, we should

(a) Increase line resistance
(b) Increases transmission voltage
(c) Decrease line reactance
(d) Both (b) & (c)

205. What are considered as a point of constant voltage in a system ? [MP JE – 2016]

(a) Buses
(b) Nodes
(c) both of the above
(d) None of the above

206. In pure resistive circuit power factor will be

(a) One
(b) Zero
(c) Infinity
(d) Half

207. In pure capacitive circuit the angle of voltage with respect to current is

(a) 0°
(b) 90° leading
(c) 90° lagging
(d) None of the above

208. Skin effect results

(a) Resistance in ac > resistance in dc
(b) Resistance in ac = resistance in dc
(c) Resistance in ac < resistance in dc
(d) None of these

209. An overhead line having surge impedance of 500 ohms is connected with an underground cable of surge impedance 150 ohms. If a surge of 70 kV travels from line towards the cable junctions, the value of transmitted voltage wave at the junction is

(a) 31.874 kV
(c) 32.30 kV
(b) 24.48 kV
(d) 29.89 kV

210. The transient stability of a power system can be increased by introducing

(a) shunt inductance
(b) shunt capacitance
(c) series capacitance
(d) series inductance [UPPCL (AE) – 2015]

211. The charging reactance of 50 km length of the line is 1500 Ω. What will be the charging reactance for 100 km length of the line?

(a) 1500 Ω 
(b) 750  Ω 
(c) 3000 Ω 
(d) 600  Ω  [UPPCL (AE) – 2015]

212. For stability and economic reason, the transmission lines are operated with power angle in the range of

(a) 65° to 80°
(b) 30° to 45°
(c) 60° to 75°
(d) 10° to 25° [UPPCL (AE) – 2015]

213. If a transmission line terminated by characteristic impedance, Z_o

(a) The reflection is maximum due to termination
(b) There are a large number of maximum and minimum on the line
(c) The incident current is zero for any applied signal
(d) There is no reflection of the incident wave

214. For interconnected systems, which statement is NOT correct?

(a) Reduces the installed capacity
(b) Increases the cost of generation
(c) Decreases spinning reserve capacity
(d) Increases the service reliability

215. For flat voltage profile system, voltage regulation is

(a) 0
(b) 100
(c) 50
(d) None of the above

216. The sending and receiving end voltages of a three phase transmission line at 100 MW load are equal at 230 kV. The phase line impedance is j14 ohm. Calculate the maximum steady state power that can be transmitted over the line.

(a) 3778.5 MW
(b) 2234.56 MW
(c) 1784.19 MW
(d) 512.37 MW

217. Which of the following is most commonly used in secondary distribution

(a) 2-phase 3-wire
(b) 1-phase 2-wire
(c) 1-phase 3-wire
(d) 3-phase 4-wire

218. “Danger 440 V” plates are

(a) caution notices
(b) advisory notices
(c) information notices
(d) danger notices

219. For a fixed value of complex power flow in a transmission line having a sending end voltage V, the real power loss will be proportional to

(a) V
(b) V²
(c) 1/V²
(d) 1/V [LMRC AE 2016]

220. To limit short circuit currents, use

(a) Series reactor
(b) Series capacitors
(c) Shunt reactors
(d) Shunt capacitors

221. If the field of synchronous motor is under-excited then the power factor will be

(a) lagging
(b) Leading
(c) Unity
(d) Zero

222. In a short transmission line, resistance and inductance are found to be equal and regulation appears to be zero, then the load will be

(a) Unity power factor
(b) Zero power factor
(c) 0.707 lagging
(d) 0.707 leading

223. If the positive, negative and zero sequence reactances of an element of a power system are 0.3, 0.3 and 0.8 respectively, then the element would be a

(a) Synchronous generator
(b) Synchronous motor
(c) Static load
(d) Transmission line [Uttarakhand AE 2013]

224. Transmission line whose characteristic impedance is 100Ω  has 300Ω  terminating load. What is the percentage of reflected voltage.

(a) 33.3 %
(b) 50 %
(c) 66.6 %
(d) 55 % [BSNL TTA 2016]

225. Surge voltage originates in power systems due to

(a) Lightining
(b) Switching operations
(c) Faults
(d) Any of the above

226. With the same maximum voltage between conductors, the saving of volume of copper required in a 3 phase 3 wire system when compare with 1 phase two wire system is

(a) 5/3
(c) 4/3
(b) 3/5
(d) ¾

227. In the analysis of short transmission lines which of the following is neglected? [UPSSC – 2015]

(a) I²R loss
(b) Shunt admittance
(c) Series impedance
(d) All of the above

228. Which type of transmission line has length up to 80 km ? [MPJE – 2016]

(a) Short transmission line
(b) Medium transmission line
(c) Long transmission line
(d) Flexible transmission line

229. By which of the following changes the synchronous motor work from lagging to leading power factor

(a) field excitation
(b) load
(c) speed
(d) voltage

230. Power is to be transmitted over a large distance, say, 200 km, the required transmission voltage must be

(a) 33 kV
(b) 132 kV
(c) 66 kV
(d) 11 kV [UPPCL – 2016]

231. When the sender’s end voltage is more, the power transmitted

(a) Will be minimum
(b) Will be zero
(c) Will be unpredictable
(d) Will be maximum [UPCCL – 2016]

232. The surge impedance of a 3-phase, 400 kV transmission line is 400 Ω. The surge impedance loading (SIL) is

(a) 400 MW
(b) 1600 MW
(c) 200 MW
(d) 100 MW [UPPCL (JE) – 2016]

233. It is given that for a system, the equivalent radius of each conductor is ‘X’. Find the equivalent radius or self-(GMD) geometric mean distance) for four bundled conductor apart by a distance ‘a’ from their centers.

(a) 1.024 X^1/2a^3/4
(b) 1.024 X^1/4a^3/4
(c) 2.024 X^1/4a^3/2
(d) 2.024 X^1/2a^3/2

234. Which of the following lines is non-radiating ? [Uttarakhand AE – 2013]

(a) Open two wire
(b) Co-axial
(c) both of the above
(d) None of the above

235. In Ferranti effect the

(a) sending end voltage is equal to the receiving end voltage
(b) sending end voltage is less than the receiving end voltage
(c) sending end voltage is greater than the receiving end voltage
(d) the sending end voltage is not equal to the receiving end voltage

236. Ferranti effect on long overhead lines is experienced when it is

(a) Lightly loaded
(b) On full load at unity p.f.
(c) On full load at 0.8 p.f. lag.
(d) In all cases

237. The string efficiency of ‘n’ units is defined as

(a) Flash over voltage of string of n units
(b) Flash over voltage of string of n units / n x flash over voltage of one unit
(c) n times flash over voltage of one unit/Flash over voltage of string of n units
(d) n times flash over voltage on one unit

238. The minimum ground clearance of the bottom most conductor for a high voltage line is

(a) 16 feet
(b) 15 feet
(c) 18 feet
(d) 20 feet

239. Phase advance are used with induction motors to

(a) Reduce noise
(b) Reduce vibrations
(c) Reduce copper losses
(d) Improve power factor

240. Pin type insulators are employed upto

(a) 11 kV
(b) 33 kV
(c) 66 kV
(d) 132 kV [UPPCL-JE – 2016]

241. What is the effect of critical voltage of corona in case of bundle conductors compared with single conductor ?

(a) Remain same
(b) Decrease
(c) Increase
(d) Not occur

242. ACSR stand for

(a) Aluminium copper steel reinforced
(b) Aluminium conductor steel reinforced
(c) All copper standard steel reinforced
(d) All copper steel reinforced conductor

243. The string efficiency of an insulator can be increased by

(a) increasing the number of strings in the insulator
(b) Reducing the number of string
(c) correct grading of insulators of various capacitances
(d) None of these

244. What type of insulators are used whenever the conductors are dead ended and there is a change in the direction of transmission line?

(a) Shackle type
(b) Strain type
(c) Pin type
(d) Suspension type

245. What is the minimum clearance of HV lines from ground across streets?

(a) 3 meters
(b) 8 meters
(c) 6 meters
(d) 5 meters

246. The surge impedance of a 100 km long transmission line is 100 Ω. For a 50km long transmission line the surge impedance is

(a) 25 ohm
(b) 50 ohm
(c) 75 ohm
(d) 100 ohm

247. In a three unit insulator string, voltage across lowest unit is 17.5 kV and string efficiency is 84.28%. What is the total voltage across the string?

(a) 8.825 kV
(b) 44.25 kV
(c) 88.25 kV
(d) 442.5 kV

248. The non-uniform distribution of voltage across the units in a string of suspension insulators is due to

(a) Unequal self capacitance of the units
(b) The existence of stray capacitance between the metallic junctions of the units and the tower body
(c) Non uniform distance of separation of the units from the tower body
(d) Non uniform distance between the cross-arm and the units

249. Equivalent model is quite suitable for analyzing the performance of transmission line of

(a) 50 km length
(b) 150 km length
(c) 250 km length
(d) All of these

250. Overhead lines generally use

(a) Copper conductors
(b) all aluminium conductors
(c) ACSR conductors
(d) Insulated conductors