Technical Interview: Electrical and Electronics Engineering: Questions

Doorsteptutor material for competitive exams is prepared by world's top subject experts: get questions, notes, tests, video lectures and more- for all subjects of your exam.

Electrical and Electronics Engineering

141) Explain the working principle of differential relay. Explain the reasons for providing large bias settings in transformers differential relays.

142) Classify circuit breakers. List the pre-commissioning tests carried on circuit breakers.

143) Explain the routine tests carried out on circuit breakers.

144) Define R. R. R. V and list the factors on which R. R. R. V depends.

145) Explain the effects of power factor and armature reaction on recovery voltage.

146) What do you understand about field emission and thermal emission?

147) Explain the phenomenon of auto-reclosing. What are the advantages of single shot re-closing and multi-shot reclosing?

148) What is meant by basic Insulation Level of equipment? Explain its significance in power system studies.

149) Define corona. What is the advantage of corona in A. C. as well as D. C lines?

150) What is meant by surge impedance and surge impedance loading? Explain its significance in transmission lines. What is the range of surge impedance for an overhead line and underground line?

151) What is equivalent spacing of a three phase lines and state its significance of bundled conductors.

152) What do you understand about infinite busbars? What is the surge impedance value of infinite bus bar?

153) What is electromagnetic interference between communication lines and power lines? Explain its effects and the methods to reducing it.

154) What are the advantages and limitations of adopting high voltage for transmission?

155) What are the practical limitations to apply Kelvin՚s law for economic size of the conductor?

156) What is meant by skin effect and proximity effect? What are the factors on which these depend?

157) List the properties of and state the draw backs of circuit breakers.

158) List out different types of faults that occur in stator and rotor of an alternator.

159) What do you understand about insulation resistance? What is the order of insulation resistance of HV circuit breaker?

160) Draw and explain voltage and current travelling wave forms of a transmission line if surge impedance of the line is equal to load.

161) What do you understand by a zone of protection? Explain how do we decide the protective zones in the electrical transmission systems?

162) Explain the working principle of undervoltage relay and state its applications.

163) Difference between belted and screened types of cables. Explain capacitance grading of cables.

164) Differentiate between a fuse and an overcurrent relay.

165) Define fusing current. State the factors on which the fusing current depends.

166) Explain the working principle of HRC fuse. Draw current cut-off and recovery voltage characteristics of HRC fuse.

167) Explain the working principle of a plain oil circuit breaker. State the factor on which the performance of a plain oil circuit breaker depends.

168) What do you understand about counterpoises? Draw different arrangements of counterpoises.

169) Explain the working principle of surge arrester. Where and how do we connect a surge arrester? Draw ideal characteristics of surge arrester.

170) What is the function of spillways? List the commonly used spillways.

171) Explain how precipitation, evaporation and run-off are inter-related?

172) List the special features of an alternators used in hydro-electric power plants.

173) Differentiate between a jet condenser and a surface condenser.

174) Classify different coals used for thermal power plant and specify their ash contents. What are the factors on which the selection of coal for thermal power plant depends?

175) Which public sector company is associated with erection and commissioning of thermal power plants in India? What is its current total installed capacity?

176) Which public sector company is associated with manufacturing thermal power plant equipment in India?

177) Define load factor. What is the average load factor of steam power plants in India?

178) What is natural draught? What are the factors on which magnitude of natural draught depends?

179) What is load shedding? When the load shedding and restoring is done?

180) Classify different insulators used in power system. State the causes of failure of insulators.

181) What do you understand about transposition of lines? Explain how the transposition is done.

182) List the different types of laying the underground cable and state the drawbacks of direct laying of underground cables.

183) Classify the insulating material based on temperature. What are the main characteristics required for the main characteristics required for the insulating materials used for underground cables?

184) Explain the principle of operation of buchholz relay and state its limitations.

185) Name the different types of faults that usually occur in cables. How do we localize them?

186) Distinguish between Varley loop test and Murray loop test.

187) Why do we use to express the reactance՚s of various elements in percentage values for short circuit calculations?

188) Explain why the neutral grounding impedance appears as in the zero-sequence equivalent circuit?

189) Show that the positive and negative sequence currents are equal in magnitude but out of phase by in a line fault.

190) Classify protective relays. What do you understand about time setting and current setting in relays?

191) Write universal torque equation. Obtain directional relay characteristics from it.

192) Draw the load ability characteristics of transmission line. Explain its significance.

193) What is field of the alternator immediately after disconnecting from the faulty system?

194) Explain the working principle of harmonic restraint relay.

195) What do you understand about incipient and through faults?

196) Explain the working principle of IDMT relay. Explain why IDMT relays are most suitable for radial feeders?

197) What do you understand about zones of protection and unit type of protection?

198) Explain Merz-price protection. Why it is not suitable beyond 33kV?

199) What is the difference between surge absorber and surge diverter?

200) Explain working principle of lightning arrester. Define the impulse ratio of lightning arrester.

201) Define symmetrical breaking current and asymmetrical breaking current. Explain why symmetrical breaking current in a circuit breaker?

202) Define sag and list the factors that affecting the sag in a transmission line.

203) Define string efficiency. Why distribution of voltage across the discs in an insulator string is not uniform?

204) Draw the typical characteristics of receiving end voltage, current and power as a function of load demand for a simple radial system.

205) What do you understand about power circle diagrams and list the information that can be obtained from.

206) Distinguish between power circle diagram and universal power circle diagram.

207) What do you understand about tuned power transmission lines?

208) What do you understand about hollow, bundled and ACSR conductors?

209) Distinguish between high resistance and low resistance methods of arc extinction.

210) Explain the working principle of carrier current protection. Explain why it is suitable for interconnected lines.

211) Explain the working principle of biased circulating current protection and state its advantages.

212) Compare HVD&HVAC transmission systems.

213) Write the sending end and receiving end power expressions in terms of A, B, C and D parameters for a transmission with 2 bus system.

214) Write A, B, C and D parameters for two transmission lines connected in series and parallel.

215) From the , ve and zero sequence phasors obtain the resultant phase phasors.

216) Explain the principle of operation of electromagnetic type distance relay.

217) Explain the working principle of a DC circuit breaker.

218) Draw the schematic diagram and explain operating characteristics of an impedance relay.

219) Draw the contact circuit of a 3-zone impedance protection and explain its operating characteristics.

220) What is meant by polarizing coil? Why do we use polarizing coil in protective relays?

Developed by: