MCQ Questions on Transmission & Distribution

150. A protective device, which reduces the steepness of wave front of a surge by absorbing surge energy, is called

(a) Surge diverters
(b) Surge absorbers
(c) Switching surges
(d) Earthing screen [UPPCL JE – 2018]

151. Which of the following groups are examples of insulators?

(a) Plastic, silver, aluminium, wood
(b) Glass, plastic, wood, porcelain
(c) Glass, aluminium, wood, rubber
(d) Air, plastic, copper, wood

152. Which of the following is used to neutralize the Ferranti effect in the medium and long transmission lines? [UPPCL JE – 2018]

(a) Shunt capacitor
(b) Series resistor
(c) Series capacitor
(d) Shunt reactor

153. Compare to 16 SWG wire 8 SWG wire is

(a) thinner
(b) thicker
(c) equal
(d) lighter

154. By which of the following systems electric power may be transmitted?

(a) Overhead system
(b) Underground system
(c) Both (a) and (b)
(d) None of the above

155. The underground system cannot be operated above

(a) 440 V
(b) 11 kV
(c) 33 kV
(d) 66 kV

156. Overhead system can be designed for operation up to

(a) 11 kV
(b) 33 kV
(c) 66 kV
(d) 400 kV

157. Which one of the following materials is not used for transmission and distribution of electrical power?

(a) Copper
(b) Aluminium
(c) Steel
(d) Tungsten

158. If the supply frequency increases, then skin effect is

(a) increased
(b) decreased
(c) unaltered
(d) infinity

159. The cable size can be reduced by

(a) use of intersheaths only
(b) use of capacitance grading only
(c) use of both intersheaths and capacitance grading
(d) selecting insulation of very high dielectric strength

160. Which of the following layer is coated in galvanization

(a) Glass
(b) Cu
(c) Zn
(d) Al

161. If a transmission line is of 310 km, then the line is considered as a

(a) very short line
(b) short line
(c) long line
(d) medium line

162. A bipolar HVDC transmission line has two poles

(a) One positive and other negative
(b) Both Positive
(c) Both negative
(d) None of the above alternative

163. Transmission lines and distribution lines can be discriminated by

(a) the size of conductor
(b) the operating voltage
(c) the amount of current carried by the line
(d) None of these

164. The input impedance of a line of infinite length is equal to…………

(a) Zero
(b) Z_o/2
(c) Z_o
(d) Infinity

165. Among the following statements which one is true ?

(a) AC transmission is more efficient
(b) DC transmission is more efficient
(c) Both are equally efficient
(d) Low voltage d.c. transmission is more efficient

166. Any length of transmission line may be made to appear as an infinitely long line by

(a) leaving the line open at the end
(b) increasing the standing wave ratio above unity
(c) shorting the line at the end
(d) terminating the line in its characteristic impedance

167. Transmission lines are generally operated at

(a) 132 kV to 220 kV
(b) 30 kV to 66 kV
(c) Upto 11 kV only
(d) 0.415 kV to 11 kV

168. For long distance line, voltage is measured in

(a) Volt
(b) Milli volt
(c) Kilovolts
(d) Micro volt

169. A 3-Phase supply feeds a load consisting of three equal star connected resistors. If one of the resistor is removed, the load power is

(a) Reduced by 25%
(b) Reduced by 33.3%
(c) Reduced by 50%
(d) Reduced by 66.6%

170. What are the advantages of DC transmission system over AC transmission system?

(a) DC system is economical for long line
(b) There is no skin effect in DC system
(c) Corona limits are highest for DC circuit as compared to AC circuit
(d) All of the above [UPSSC 2015]

171. Voltage under extra high voltage are

(a) 1 kV and above
(b) 11 kV and above
(c) 132 kV and above
(d) 220 kV and above

172. All transmission and distribution systems are ……….. phase system.

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

173. Which of the following lines has highest steady state limit? [UPPCL AE 2016]

(a) 132 kV
(b) 66 kV
(c) 220 kV
(d) 400 kV

174. Which of the following is not the correct statement regarding direct current transmission ? [UPPCL JE 2016]

(a) Corona effect is less
(b) Voltage regulation is good
(c) Skin effect is negligible
(d) There is a continuous power loss

175. Length of medium transmission line is

(a) 10 – 15 km
(b) 50 – 150 km
(c) 150 – 250 km
(d) more than 250 km

176. In the case of HVDC transmission system, which of the statement is true?

(a) There is neither charging current nor skin effect
(b) No charging current but skin effect is present
(c) Both charging current and skin effects are present
(d) There are charging current but no skin effect.

177. At power frequencies, skin and proximity effects are………… frequency.

(a) independent of
(b) negligible at small
(c) important at small
(d) negligible at large

178. The reactive power

(a) fully loaded overhead lines absorb and lightly loaded generate
(b) fully loaded and lightly loaded overhead lines generate
(c) fully loaded overhead lines generate and Lightly loaded absorb
(d) fully loaded and lightly loaded overhead lines absorb

179. An ac current passing through a conductor distributes ……….. throughout the cross section and is frequency ………….

(a) non uniformly and independent
(b) non uniformly and dependent
(c) uniformly and independent
(d) uniformly and dependent

180. If transmission line reactance X and resistance R are ……. the flow of reactive power is approximately independent of real power. [UPRVUNL JE 2016]

(a) X ≠ R
(b) X > R
(c) X = R
(d) X < R

181. If Z_oc and Z_sc are the impedances measured at the sending end with receiving end open-circuited and short-circuited respectively, then surge impedance can also be defined as

(a) Z_c = √(Z_sc/Z_oc)
(b) Z_c = √(Z_oc.Z_sc)
(c) Z_c= √(Z_oc/Z_ac)
(d) Z_c = Z_oc

182. Transposition of conductors in large transmission lines results in

(a) same average capacitance for various phase over the entire length of the conductor
(b) averaging is valid only for inductance and not capacitance
(c) same average inductance for various phases over the entire length of the conductor
(d) same average inductance and capacitance for various phase over the entire length of the conductor

183. The A.C. resistance of the conductor is more than D.C. resistance, due to

(a) Proximity effect
(b) Skin effect
(c) Both (a) & (b)
(d) None of these

184. A loss less transmission line having surge impedance loading of 2280 MW is provided with a uniformly distributed series capacitive compensation of 30%. Then SIL of the compensated transmission line will be

(a) 1835 MW
(b) 2280 MW
(c) 2725 MW
(d) 3275 MW [LMRC AE – 2016]

185. If the inductance of line increases, transmission capacity will

(a) Increase
(b) Decrease
(c) Remain same
(d) Impendent of inductance

186. A conductor is composed of seven identical copper strands of radius ‘r’ each. What is the self GMD (Geometric Mean Distance) of the conductor ? [Uttarakhand AE – 2013]

(a) 2.771 r
(b) 2.177 r
(c) 7.122 r
(d) 7.777 r

187. For secondary distribution, the transformer(s) used is/are

(a) Auto Transformer
(b) Star-Delta and Delta-Star Transformer both
(c) Star-Delta Power Transformer
(d) Delta-Star Distribution Transformer

188. In High Power Lines the power is at

(a) high current level and low voltage
(b) high voltage level and low current
(c) any combination
(d) None of these

189. If a Transmission line is terminated with a resistance equal to its characteristic impedance

(a) The line loss will be maximum
(b) The input impedance will be twice the terminating resistance
(c) The standing wave ratio will be minimum
(d) The standing wave ratio will be maximum

190. A transmission line is distortion less if

(a) RL = 1/GC
(b) RL = GC
(c) LG = RC
(d) RG – LC [UPSSC-JE 2015]

191. The effective resistance of a coil at high frequencies is more than its d.c. resistance on account of

(a) Skin effects
(b) Proximity effect
(c) Eddy current losses
(d) all of these

192. Negative voltage regulation is indicative that the load is

(a) capacitive only
(b) inductive only
(c) inductive or resistive
(d) None of the above

193. AC supply system compared to DC supply system has the advantage

(a) Power factor
(b) Reactive elements
(c) Voltage drop
(d) Low cost of switching [DMRC – 2014]

194. The length of the conductor increased by 3 times then it’s resistance will be

(a) thrice
(b) six times
(c) times
(d) half

195. Consider the following statements

High voltage is used in long distance power transmission in order to:

1. Reduce the time of transmission
2. Reduce the transmission losses
3. Make the system reliable

Out of these, the correct statements are ?
(a) Only B
(b) All three
(c) Only A and B
(d) Only A and C

196. Skin effect is only noticeable at ………… frequencies. [UPRVUNL 2015]

(a) Audio
(b) Low
(c) High
(d) All

197. The skin effect of the conductor increases the effective value of

(a) Inductance of the conductor
(b) Resistance of the conductor
(c) Capacitance of the conductor
(d) None of these

198. Stranded wires are mainly used to

(a) reduce skin effect
(b) reduce metal fatigue
(c) reduce proximity effect
(d) both (b) and (c)

199. The characteristic impedance of a loss less line is called

(a) leakage impedance
(b) Peak impedance
(c) Small impedance
(d) Surge impedance [UPSSC – 2015]