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161. Vacuum circuit breakers (VCBs) are commonly used at medium-voltage levels mainly because they offer:
- A. Unlimited current capacity with no rating limits
- B. The ability to step up voltage directly
- C. Elimination of the need for any protection relay
- D. Reliable arc interruption in a vacuum interrupter with low maintenance requirements
Answer: Reliable arc interruption in a vacuum interrupter with low maintenance requirements
Explanation: Reliable arc interruption in a vacuum interrupter with low maintenance requirements — verified fact for Railway Electrical Engineering Group B LDCE.
162. SF6 (sulphur hexafluoride) circuit breakers are used in some substations mainly because SF6 gas offers:
- A. Higher conductivity than copper wire
- B. A permanent replacement for all transformers
- C. Excellent arc-quenching and insulating properties, allowing compact, reliable high-voltage switching
- D. The ability to generate electrical power on its own
Answer: Excellent arc-quenching and insulating properties, allowing compact, reliable high-voltage switching
Explanation: Excellent arc-quenching and insulating properties, allowing compact, reliable high-voltage switching — verified fact for Railway Electrical Engineering Group B LDCE.
163. A voltage transformer (VT/PT) in a substation is used mainly to:
- A. Replace the main step-down transformer entirely
- B. Provide a proportionally scaled-down voltage signal for metering and protection relays
- C. Directly power the traction motors of a locomotive
- D. Generate the substation's own independent power supply
Answer: Provide a proportionally scaled-down voltage signal for metering and protection relays
Explanation: Provide a proportionally scaled-down voltage signal for metering and protection relays — verified fact for Railway Electrical Engineering Group B LDCE.
164. A current transformer (CT) used for protection/metering in a traction substation functions to:
- A. Step up the traction voltage for the OHE
- B. Step down a large primary current to a small, standardized secondary current suitable for relays and meters
- C. Generate reactive power for power factor correction
- D. Physically switch the main circuit on and off
Answer: Step down a large primary current to a small, standardized secondary current suitable for relays and meters
Explanation: Step down a large primary current to a small, standardized secondary current suitable for relays and meters — verified fact for Railway Electrical Engineering Group B LDCE.
165. A key safety reason isolators must generally only be operated when the circuit is already de-energized (no load current flowing) is that:
- A. They automatically generate reactive power when operated under load
- B. They are more expensive than circuit breakers
- C. They lack an arc-quenching mechanism, so breaking load current under load could cause a dangerous arc flash
- D. Operating them under load increases the OHE's mechanical tension
Answer: They lack an arc-quenching mechanism, so breaking load current under load could cause a dangerous arc flash
Explanation: They lack an arc-quenching mechanism, so breaking load current under load could cause a dangerous arc flash — verified fact for Railway Electrical Engineering Group B LDCE.
166. Isolators (disconnectors) differ from circuit breakers mainly in that isolators are designed to:
- A. Provide visible physical isolation of a de-energized circuit for safe maintenance, not to interrupt load or fault current
- B. Interrupt heavy fault currents safely, exactly like a circuit breaker
- C. Measure voltage only, with no switching function
- D. Generate electrical power
Answer: Provide visible physical isolation of a de-energized circuit for safe maintenance, not to interrupt load or fault current
Explanation: Provide visible physical isolation of a de-energized circuit for safe maintenance, not to interrupt load or fault current — verified fact for Railway Electrical Engineering Group B LDCE.
167. Bus-bars in a traction substation switchyard are used to:
- A. Generate three-phase power locally
- B. Serve as common connection points from which multiple outgoing feeders/circuits can be supplied
- C. Cool the transformer oil
- D. Store energy for use during power cuts
Answer: Serve as common connection points from which multiple outgoing feeders/circuits can be supplied
Explanation: Serve as common connection points from which multiple outgoing feeders/circuits can be supplied — verified fact for Railway Electrical Engineering Group B LDCE.
168. A booster transformer, where used in traction supply systems, mainly helps to:
- A. Eliminate the need for a traction substation
- B. Force the traction return current to flow through a dedicated return conductor instead of dispersing into the general earth, reducing interference
- C. Replace the pantograph on the locomotive
- D. Directly increase the OHE's mechanical tension
Answer: Force the traction return current to flow through a dedicated return conductor instead of dispersing into the general earth, reducing interference
Explanation: Force the traction return current to flow through a dedicated return conductor instead of dispersing into the general earth, reducing interference — verified fact for Railway Electrical Engineering Group B LDCE.
169. Ferranti effect, a phenomenon relevant to long transmission/feeder lines under light load, refers to:
- A. The receiving-end voltage becoming higher than the sending-end voltage due to the line's capacitance
- B. An increase in current with no change in voltage
- C. A permanent short circuit condition
- D. A sudden drop in voltage to zero under all load conditions
Answer: The receiving-end voltage becoming higher than the sending-end voltage due to the line's capacitance
Explanation: The receiving-end voltage becoming higher than the sending-end voltage due to the line's capacitance — verified fact for Railway Electrical Engineering Group B LDCE.
170. One practical method to reduce voltage drop over long traction feeding sections is to:
- A. Remove all circuit breakers from the system
- B. Reduce the cross-sectional area of the contact wire
- C. Provide additional feeding points/substations or booster transformers along the route to shorten the effective feeding distance
- D. Increase the spacing between OHE masts indefinitely
Answer: Provide additional feeding points/substations or booster transformers along the route to shorten the effective feeding distance
Explanation: Provide additional feeding points/substations or booster transformers along the route to shorten the effective feeding distance — verified fact for Railway Electrical Engineering Group B LDCE.
171. Voltage drop along a long OHE feeding section under heavy traction load is a real technical concern mainly because it can:
- A. Increase the speed of the train automatically
- B. Reduce the voltage available at the pantograph, potentially limiting locomotive performance
- C. Improve the power factor of the system automatically
- D. Have no effect on locomotive performance whatsoever
Answer: Reduce the voltage available at the pantograph, potentially limiting locomotive performance
Explanation: Reduce the voltage available at the pantograph, potentially limiting locomotive performance — verified fact for Railway Electrical Engineering Group B LDCE.
172. Power factor correction capacitors are sometimes used in traction supply systems mainly to:
- A. Eliminate the need for any circuit breakers
- B. Replace the function of a transformer entirely
- C. Improve the power factor closer to unity, reducing reactive current and associated losses
- D. Increase the traction voltage supplied to the OHE
Answer: Improve the power factor closer to unity, reducing reactive current and associated losses
Explanation: Improve the power factor closer to unity, reducing reactive current and associated losses — verified fact for Railway Electrical Engineering Group B LDCE.
173. A traction load with a lagging power factor (due to inductive components like transformers and traction motors) generally causes:
- A. Higher current draw for the same real power, increasing losses and voltage drop in the supply system
- B. Zero reactive power in the circuit
- C. Complete elimination of transmission losses
- D. Automatically reduced current draw for the same real power
Answer: Higher current draw for the same real power, increasing losses and voltage drop in the supply system
Explanation: Higher current draw for the same real power, increasing losses and voltage drop in the supply system — verified fact for Railway Electrical Engineering Group B LDCE.
174. Power factor in an AC traction circuit is defined as the:
- A. Ratio of voltage to current only, with no reference to phase angle
- B. Ratio of resistance to reactance only
- C. Ratio of real (active) power to apparent power in the circuit
- D. Total energy consumed per day
Answer: Ratio of real (active) power to apparent power in the circuit
Explanation: Ratio of real (active) power to apparent power in the circuit — verified fact for Railway Electrical Engineering Group B LDCE.
175. A low earth resistance value at a substation earthing installation is generally desirable because it helps:
- A. Reduce the transformer's voltage ratio
- B. Eliminate the need for circuit breakers
- C. Increase the amount of current the OHE can carry to trains
- D. Ensure fault currents are diverted safely and touch voltages remain within safe limits
Answer: Ensure fault currents are diverted safely and touch voltages remain within safe limits
Explanation: Ensure fault currents are diverted safely and touch voltages remain within safe limits — verified fact for Railway Electrical Engineering Group B LDCE.
176. Earthing (grounding) of electrical equipment and structures near the traction system primarily serves to:
- A. Increase the voltage available to the locomotive
- B. Provide a safe path for fault current and limit touch/step voltages to protect personnel and equipment
- C. Improve the aesthetic appearance of masts
- D. Reduce the weight of the OHE structure
Answer: Provide a safe path for fault current and limit touch/step voltages to protect personnel and equipment
Explanation: Provide a safe path for fault current and limit touch/step voltages to protect personnel and equipment — verified fact for Railway Electrical Engineering Group B LDCE.
177. An earth fault in an OHE circuit refers to a condition where:
- A. The train is running exactly on schedule
- B. Current unintentionally flows from a live conductor to earth through an unintended path
- C. The pantograph is correctly aligned with the contact wire
- D. Voltage is perfectly balanced across all three phases
Answer: Current unintentionally flows from a live conductor to earth through an unintended path
Explanation: Current unintentionally flows from a live conductor to earth through an unintended path — verified fact for Railway Electrical Engineering Group B LDCE.
178. Distance protection is sometimes used on long OHE feeder sections mainly because it can:
- A. Directly repair the fault without any human intervention
- B. Increase the supply voltage automatically
- C. Estimate the location of a fault based on the impedance measured, helping identify roughly where along the line the fault occurred
- D. Eliminate the need for any circuit breakers
Answer: Estimate the location of a fault based on the impedance measured, helping identify roughly where along the line the fault occurred
Explanation: Estimate the location of a fault based on the impedance measured, helping identify roughly where along the line the fault occurred — verified fact for Railway Electrical Engineering Group B LDCE.
179. An overcurrent relay is designed to operate mainly when:
- A. Voltage drops slightly below normal for a very brief moment only
- B. The circuit breaker is manually opened for routine maintenance
- C. Ambient temperature rises above 50 degrees Celsius regardless of current
- D. Current in the protected circuit exceeds a preset threshold, indicating a possible fault or overload
Answer: Current in the protected circuit exceeds a preset threshold, indicating a possible fault or overload
Explanation: Current in the protected circuit exceeds a preset threshold, indicating a possible fault or overload — verified fact for Railway Electrical Engineering Group B LDCE.
180. A protective relay in a traction power circuit primarily functions to:
- A. Generate the traction supply voltage
- B. Replace the need for any circuit breaker
- C. Physically carry the full traction load current continuously as its main duty
- D. Sense abnormal conditions (like overcurrent or earth fault) and signal the circuit breaker to trip
Answer: Sense abnormal conditions (like overcurrent or earth fault) and signal the circuit breaker to trip
Explanation: Sense abnormal conditions (like overcurrent or earth fault) and signal the circuit breaker to trip — verified fact for Railway Electrical Engineering Group B LDCE.
181. In traction substations, circuit breakers are essential mainly because they:
- A. Only measure voltage without any switching function
- B. Can safely interrupt fault or overload current, protecting equipment and preventing wider damage
- C. Permanently connect the circuit with no ability to disconnect
- D. Only work when current is already at zero
Answer: Can safely interrupt fault or overload current, protecting equipment and preventing wider damage
Explanation: Can safely interrupt fault or overload current, protecting equipment and preventing wider damage — verified fact for Railway Electrical Engineering Group B LDCE.
182. A step-down transformer with a primary-to-secondary turns ratio of 10:1 connected to a 11kV supply will ideally produce a secondary voltage of approximately:
- A. 0.11 kV
- B. 1.1 kV
- C. 110 kV
- D. 11 kV
Answer: 1.1 kV
Explanation: 1.1 kV — verified fact for Railway Electrical Engineering Group B LDCE.
183. A traction substation transformer typically steps down the incoming high-voltage grid supply to a level suitable for feeding the 25kV OHE using which basic principle?
- A. Chemical energy storage and release
- B. Mechanical gear reduction
- C. Direct current rectification only
- D. Electromagnetic induction between primary and secondary windings, changing voltage in proportion to the turns ratio
Answer: Electromagnetic induction between primary and secondary windings, changing voltage in proportion to the turns ratio
Explanation: Electromagnetic induction between primary and secondary windings, changing voltage in proportion to the turns ratio — verified fact for Railway Electrical Engineering Group B LDCE.
184. Under 25kV AC traction, the term 'RVT' or return conductor arrangement is used on some sections mainly to help mitigate:
- A. Interference with nearby telecom/signalling circuits caused by traction return current in the rails
- B. Wheel wear on rolling stock
- C. Track gauge variation
- D. Fuel consumption of diesel locomotives
Answer: Interference with nearby telecom/signalling circuits caused by traction return current in the rails
Explanation: Interference with nearby telecom/signalling circuits caused by traction return current in the rails — verified fact for Railway Electrical Engineering Group B LDCE.
185. A key reason lightning arresters (surge arresters) are installed on OHE/substation equipment is to:
- A. Increase the normal operating voltage of the OHE
- B. Protect equipment from voltage surges caused by lightning strikes or switching transients
- C. Provide additional mechanical support to the wire
- D. Improve pantograph contact quality
Answer: Protect equipment from voltage surges caused by lightning strikes or switching transients
Explanation: Protect equipment from voltage surges caused by lightning strikes or switching transients — verified fact for Railway Electrical Engineering Group B LDCE.
186. OHE 'cantilever' assemblies mounted on masts are used to:
- A. Support and position the catenary and contact wire at the correct height and alignment over the track
- B. Carry signalling cables exclusively
- C. Serve as a lightning rod only, with no OHE function
- D. Generate electrical power directly
Answer: Support and position the catenary and contact wire at the correct height and alignment over the track
Explanation: Support and position the catenary and contact wire at the correct height and alignment over the track — verified fact for Railway Electrical Engineering Group B LDCE.
187. A 'composite' OHE mast supporting multiple tracks in a yard is used mainly to:
- A. House the station's signalling relay room
- B. Increase the traction voltage in the yard
- C. Economize on the number of masts/foundations needed by supporting cantilevers for more than one track from a common structure
- D. Replace the need for a substation
Answer: Economize on the number of masts/foundations needed by supporting cantilevers for more than one track from a common structure
Explanation: Economize on the number of masts/foundations needed by supporting cantilevers for more than one track from a common structure — verified fact for Railway Electrical Engineering Group B LDCE.
188. General awareness: which of the following is a real, publicly known milestone in Indian Railways electrification history?
- A. Steam locomotives were banned in India before the first electrified line opened
- B. India electrified its entire network before any other country in the world attempted electrification
- C. Suburban sections around Mumbai were among the earliest electrified sections in India, in the mid-20th century
- D. All Indian Railways lines were electrified before independence in 1947
Answer: Suburban sections around Mumbai were among the earliest electrified sections in India, in the mid-20th century
Explanation: Suburban sections around Mumbai were among the earliest electrified sections in India, in the mid-20th century — verified fact for Railway Electrical Engineering Group B LDCE.
189. The zonal Railway's Electrical Department is generally responsible for which broad set of assets, distinct from the Signal & Telecom department?
- A. Signal interlocking logic and train detection circuits exclusively
- B. Track geometry and ballast maintenance exclusively
- C. Traction distribution (OHE, substations), electric locomotives/EMU electrical systems, and general electrical installations (lighting, power supply to buildings)
- D. Passenger reservation software exclusively
Answer: Traction distribution (OHE, substations), electric locomotives/EMU electrical systems, and general electrical installations (lighting, power supply to buildings)
Explanation: Traction distribution (OHE, substations), electric locomotives/EMU electrical systems, and general electrical installations (lighting, power supply to buildings) — verified fact for Railway Electrical Engineering Group B LDCE.
190. General awareness: RDSO (Research Designs and Standards Organisation), based in Lucknow, plays which broad role relevant to railway electrical/OHE standards?
- A. Selling passenger tickets across zones
- B. Developing and standardizing technical specifications, designs, and research for railway electrical and other engineering systems
- C. Operating railway catering services
- D. Running the national railway budget presentation
Answer: Developing and standardizing technical specifications, designs, and research for railway electrical and other engineering systems
Explanation: Developing and standardizing technical specifications, designs, and research for railway electrical and other engineering systems — verified fact for Railway Electrical Engineering Group B LDCE.
191. Foot-operated or motor-operated isolators/switches along the OHE feeding system allow railway staff to:
- A. Change the train's timetable
- B. Adjust the rail gauge
- C. Manually or remotely isolate a section of OHE for safe maintenance or in response to a fault
- D. Control signal aspects directly
Answer: Manually or remotely isolate a section of OHE for safe maintenance or in response to a fault
Explanation: Manually or remotely isolate a section of OHE for safe maintenance or in response to a fault — verified fact for Railway Electrical Engineering Group B LDCE.
192. An overhead line's 'mid-point anchor' is used mainly in longer tension lengths to:
- A. Function as a substitute for a substation
- B. Change the traction voltage midway
- C. Limit the movement of the wire so that thermal expansion is distributed more evenly and does not cause excessive displacement at one end
- D. Add extra current-carrying capacity
Answer: Limit the movement of the wire so that thermal expansion is distributed more evenly and does not cause excessive displacement at one end
Explanation: Limit the movement of the wire so that thermal expansion is distributed more evenly and does not cause excessive displacement at one end — verified fact for Railway Electrical Engineering Group B LDCE.
193. An 'anti-creep' or anchor arrangement is provided at the ends of OHE tension lengths mainly to:
- A. Increase the resistance of the contact wire
- B. Hold the wire firmly at a fixed point so that tensioning devices can properly regulate the rest of the span
- C. Change the phase of the traction supply
- D. Provide a location for passenger boarding
Answer: Hold the wire firmly at a fixed point so that tensioning devices can properly regulate the rest of the span
Explanation: Hold the wire firmly at a fixed point so that tensioning devices can properly regulate the rest of the span — verified fact for Railway Electrical Engineering Group B LDCE.
194. The main reason overhead electrification (as opposed to a third-rail system) is preferred for Indian main lines is:
- A. Better suitability for high-speed, high-voltage operation and safety, since a third rail at high voltage poses greater public safety risk at level crossings and yards
- B. Third rail systems cannot carry any current at all
- C. Overhead wires are always cheaper to install than a third rail in every case
- D. Overhead wires eliminate the need for any substations
Answer: Better suitability for high-speed, high-voltage operation and safety, since a third rail at high voltage poses greater public safety risk at level crossings and yards
Explanation: Better suitability for high-speed, high-voltage operation and safety, since a third rail at high voltage poses greater public safety risk at level crossings and yards — verified fact for Railway Electrical Engineering Group B LDCE.
195. When a locomotive travels under a neutral section without power being cut off in time, the most likely immediate electrical consequence is:
- A. A flashover/short circuit between two different phases or feeding zones, potentially damaging equipment
- B. No effect at all under any circumstance
- C. An automatic increase in train speed
- D. A permanent increase in traction voltage
Answer: A flashover/short circuit between two different phases or feeding zones, potentially damaging equipment
Explanation: A flashover/short circuit between two different phases or feeding zones, potentially damaging equipment — verified fact for Railway Electrical Engineering Group B LDCE.
196. A pantograph is designed to maintain contact with the OHE contact wire through:
- A. Spring or pneumatic pressure that keeps the contact strip pressed against the wire as the pantograph height adjusts
- B. Direct bolting to the contact wire
- C. Magnetic levitation between wire and pantograph
- D. A rigid fixed arm with no vertical movement at all
Answer: Spring or pneumatic pressure that keeps the contact strip pressed against the wire as the pantograph height adjusts
Explanation: Spring or pneumatic pressure that keeps the contact strip pressed against the wire as the pantograph height adjusts — verified fact for Railway Electrical Engineering Group B LDCE.
197. A key advantage of electric traction relevant to freight operations is that electric locomotives generally offer:
- A. The ability to run without any power supply at all
- B. Higher power-to-weight ratio and better haulage capability on graded sections compared to equivalent diesel units
- C. Complete independence from any substation infrastructure
- D. Zero maintenance requirement compared to diesel locomotives
Answer: Higher power-to-weight ratio and better haulage capability on graded sections compared to equivalent diesel units
Explanation: Higher power-to-weight ratio and better haulage capability on graded sections compared to equivalent diesel units — verified fact for Railway Electrical Engineering Group B LDCE.
198. India's railway electrification effort has, as a matter of public record, expanded substantially since the mid-20th century, initially covering select suburban sections before extending to:
- A. Only metro systems unrelated to Indian Railways
- B. Only international freight corridors outside India
- C. Trunk main lines and eventually the wider broad-gauge network across zones
- D. Only airport connections
Answer: Trunk main lines and eventually the wider broad-gauge network across zones
Explanation: Trunk main lines and eventually the wider broad-gauge network across zones — verified fact for Railway Electrical Engineering Group B LDCE.
199. On a 25kV AC electrified route, the OHE and all associated metal structures that are not meant to carry current are connected to earth mainly to:
- A. Ensure safety by providing a low-resistance path for fault current, preventing dangerous touch voltages on structures
- B. Reduce the weight of the contact wire
- C. Increase the traction current available to locomotives
- D. Improve the aesthetic appearance of the mast
Answer: Ensure safety by providing a low-resistance path for fault current, preventing dangerous touch voltages on structures
Explanation: Ensure safety by providing a low-resistance path for fault current, preventing dangerous touch voltages on structures — verified fact for Railway Electrical Engineering Group B LDCE.
200. The term 'traction distribution' broadly covers the network of substations, feeders, and switching posts that together perform which function?
- A. Delivering electrical power from the grid supply to the OHE along the route reliably and safely
- B. Scheduling train timetables
- C. Controlling the interlocking of signals at stations
- D. Managing ticketing and reservation systems
Answer: Delivering electrical power from the grid supply to the OHE along the route reliably and safely
Explanation: Delivering electrical power from the grid supply to the OHE along the route reliably and safely — verified fact for Railway Electrical Engineering Group B LDCE.
201. Regular OHE maintenance activities like wire wear measurement and insulator cleaning are important mainly because they help:
- A. Increase the traction voltage supplied
- B. Prevent power interruptions and wire breakages that could disrupt train operations or create safety hazards
- C. Eliminate the need for substations
- D. Reduce the number of trains that can run
Answer: Prevent power interruptions and wire breakages that could disrupt train operations or create safety hazards
Explanation: Prevent power interruptions and wire breakages that could disrupt train operations or create safety hazards — verified fact for Railway Electrical Engineering Group B LDCE.
202. The term 'stagger' in OHE alignment refers to the:
- A. Lateral (side-to-side) displacement of the contact wire from the track centre line at successive supports
- B. The angle of the pantograph itself
- C. Vertical sag of the catenary wire between supports
- D. The delay in switching a circuit breaker
Answer: Lateral (side-to-side) displacement of the contact wire from the track centre line at successive supports
Explanation: Lateral (side-to-side) displacement of the contact wire from the track centre line at successive supports — verified fact for Railway Electrical Engineering Group B LDCE.
203. A 'switching station' or feeding post along an electrified section is generally equipped with circuit breakers and isolators mainly to allow:
- A. Water supply to nearby stations
- B. Direct passenger boarding
- C. Generation of new electrical power
- D. Safe switching, isolation, and sectionalizing of the OHE for maintenance or fault conditions
Answer: Safe switching, isolation, and sectionalizing of the OHE for maintenance or fault conditions
Explanation: Safe switching, isolation, and sectionalizing of the OHE for maintenance or fault conditions — verified fact for Railway Electrical Engineering Group B LDCE.
204. In electrified yards, OHE is generally NOT provided over certain tracks (like some loco inspection pits) primarily for reasons of:
- A. Lack of available copper wire
- B. Reduction of train speed limits
- C. Signalling interlocking conflicts only
- D. Safety, since staff need to safely access the roof/top of stabled locomotives or wagons for inspection and maintenance
Answer: Safety, since staff need to safely access the roof/top of stabled locomotives or wagons for inspection and maintenance
Explanation: Safety, since staff need to safely access the roof/top of stabled locomotives or wagons for inspection and maintenance — verified fact for Railway Electrical Engineering Group B LDCE.
205. Which of the following is a genuine reason OHE height above rail level is kept within a specified design range rather than arbitrary?
- A. To reduce the cost of track ballast
- B. To simplify signal aspect design
- C. To ensure reliable, consistent pantograph contact and clearance for rolling stock including on bridges/tunnels
- D. To match the height of nearby buildings
Answer: To ensure reliable, consistent pantograph contact and clearance for rolling stock including on bridges/tunnels
Explanation: To ensure reliable, consistent pantograph contact and clearance for rolling stock including on bridges/tunnels — verified fact for Railway Electrical Engineering Group B LDCE.
206. A 'feeder' in traction electrification, distinct from the contact wire, typically refers to a conductor used to:
- A. Carry water for locomotive cooling
- B. Carry compressed air for brakes
- C. Carry power from the substation to a feeding point on the OHE, sometimes over a separate conductor run alongside the track
- D. Carry only signalling data
Answer: Carry power from the substation to a feeding point on the OHE, sometimes over a separate conductor run alongside the track
Explanation: Carry power from the substation to a feeding point on the OHE, sometimes over a separate conductor run alongside the track — verified fact for Railway Electrical Engineering Group B LDCE.
207. On curved track, OHE registration arms and stagger are designed with extra care mainly to ensure:
- A. The pantograph maintains proper contact with the wire despite the changing track alignment
- B. The train's braking distance is reduced
- C. The signalling cables are shortened
- D. The rail gauge is widened
Answer: The pantograph maintains proper contact with the wire despite the changing track alignment
Explanation: The pantograph maintains proper contact with the wire despite the changing track alignment — verified fact for Railway Electrical Engineering Group B LDCE.
208. OHE masts are typically spaced along straight track at intervals determined mainly by:
- A. The number of trains scheduled per day
- B. Span length limits based on wind loading, wire sag, and pantograph dynamics
- C. The signalling aspect sequence
- D. The colour of the locomotive
Answer: Span length limits based on wind loading, wire sag, and pantograph dynamics
Explanation: Span length limits based on wind loading, wire sag, and pantograph dynamics — verified fact for Railway Electrical Engineering Group B LDCE.
209. A 'flexible OHE' with catenary and contact wire (as opposed to a rigid overhead conductor rail) is the standard choice for Indian main-line electrification mainly because it:
- A. Eliminates the need for a pantograph
- B. Better accommodates higher speeds and longer spans typical of main-line running
- C. Is cheaper to install than any rigid system in all cases
- D. Requires no maintenance whatsoever
Answer: Better accommodates higher speeds and longer spans typical of main-line running
Explanation: Better accommodates higher speeds and longer spans typical of main-line running — verified fact for Railway Electrical Engineering Group B LDCE.
210. The term 'RRSK' overlap or overlap span in OHE design refers to a region where:
- A. Two different traction substations are permanently short-circuited together
- B. The rail gauge changes from broad to narrow
- C. Two adjacent tension lengths of contact wire overlap so the pantograph transitions smoothly from one to the other
- D. The signalling and electrical departments share the same control panel
Answer: Two adjacent tension lengths of contact wire overlap so the pantograph transitions smoothly from one to the other
Explanation: Two adjacent tension lengths of contact wire overlap so the pantograph transitions smoothly from one to the other — verified fact for Railway Electrical Engineering Group B LDCE.
211. Electrification of a railway route generally allows a shift from diesel locomotives to electric locomotives, which has the real environmental benefit of:
- A. Making trains run without any energy input
- B. Reducing direct emissions at the point of train operation (with overall emissions then depending on the electricity generation mix)
- C. Eliminating the need for any electricity generation at all
- D. Completely eliminating all emissions everywhere including at power plants
Answer: Reducing direct emissions at the point of train operation (with overall emissions then depending on the electricity generation mix)
Explanation: Reducing direct emissions at the point of train operation (with overall emissions then depending on the electricity generation mix) — verified fact for Railway Electrical Engineering Group B LDCE.
212. A key general-awareness fact about Indian Railways' electrification progress is that, over recent years, the railway has pursued near-complete electrification of its:
- A. Only goods sheds, excluding running lines
- B. Broad-gauge route network
- C. Only metro/urban rail systems, excluding main lines
- D. Narrow-gauge routes exclusively, with broad gauge left unelectrified
Answer: Broad-gauge route network
Explanation: Broad-gauge route network — verified fact for Railway Electrical Engineering Group B LDCE.
213. The masts that support the OHE structure along the track are typically fixed to the ground on:
- A. Steel rails themselves
- B. Wooden planks laid directly on ballast
- C. Concrete foundations designed for the expected mechanical loading
- D. Floating pontoons
Answer: Concrete foundations designed for the expected mechanical loading
Explanation: Concrete foundations designed for the expected mechanical loading — verified fact for Railway Electrical Engineering Group B LDCE.
214. Loco pilots are trained to switch off traction power momentarily while a train's pantograph passes through a neutral section mainly to avoid:
- A. Excessive brake wear
- B. Arcing/short-circuiting between two out-of-phase (or dead) feeding zones through the pantograph
- C. Overheating of the driver's cab lighting
- D. Signal aspect changes
Answer: Arcing/short-circuiting between two out-of-phase (or dead) feeding zones through the pantograph
Explanation: Arcing/short-circuiting between two out-of-phase (or dead) feeding zones through the pantograph — verified fact for Railway Electrical Engineering Group B LDCE.
215. A neutral section (dead section) is provided in the OHE mainly to:
- A. Increase the traction voltage locally
- B. Electrically separate two feeding zones that may be on different phases, preventing a short-circuit when a pantograph bridges them
- C. Provide a resting point for maintenance staff
- D. Store excess electrical energy
Answer: Electrically separate two feeding zones that may be on different phases, preventing a short-circuit when a pantograph bridges them
Explanation: Electrically separate two feeding zones that may be on different phases, preventing a short-circuit when a pantograph bridges them — verified fact for Railway Electrical Engineering Group B LDCE.
216. Automatic tensioning devices are used at the ends of OHE tension lengths mainly to compensate for:
- A. Fluctuations in substation voltage
- B. Thermal expansion and contraction of the wires with temperature changes, keeping tension roughly constant
- C. Variations in train speed only
- D. Changes in signalling aspects
Answer: Thermal expansion and contraction of the wires with temperature changes, keeping tension roughly constant
Explanation: Thermal expansion and contraction of the wires with temperature changes, keeping tension roughly constant — verified fact for Railway Electrical Engineering Group B LDCE.
217. In simple OHE terminology, the length of contact/catenary wire fed from one end and terminated at an anchor is generally referred to as a:
- A. Registration arm
- B. Tension length (or overlap span at its ends)
- C. Traction substation
- D. Feeder station
Answer: Tension length (or overlap span at its ends)
Explanation: Tension length (or overlap span at its ends) — verified fact for Railway Electrical Engineering Group B LDCE.
218. An Auto-Transformer (AT) feeding system is used on some heavily loaded electrified sections mainly to:
- A. Eliminate the need for a return conductor entirely
- B. Reduce voltage drop and electromagnetic interference by using a higher transmission voltage between substations with autotransformers stepping it down along the route
- C. Convert the traction supply from AC to DC
- D. Provide backup diesel power during outages
Answer: Reduce voltage drop and electromagnetic interference by using a higher transmission voltage between substations with autotransformers stepping it down along the route
Explanation: Reduce voltage drop and electromagnetic interference by using a higher transmission voltage between substations with autotransformers stepping it down along the route — verified fact for Railway Electrical Engineering Group B LDCE.
219. The return path for traction current from the locomotive back to the substation is normally provided through the:
- A. A second overhead contact wire dedicated only to return current
- B. Running rails (and associated return/booster conductors)
- C. The station's lighting circuit
- D. The signalling telecom cable
Answer: Running rails (and associated return/booster conductors)
Explanation: Running rails (and associated return/booster conductors) — verified fact for Railway Electrical Engineering Group B LDCE.
220. A key reason 25kV AC was chosen for Indian Railways over lower DC traction voltages is that AC allows:
- A. Simple transformer step-down/step-up, enabling fewer, more widely spaced substations for a given power demand
- B. Direct use of grid supply without any transformers
- C. Storage of power directly in the rails
- D. Elimination of the need for any substations at all
Answer: Simple transformer step-down/step-up, enabling fewer, more widely spaced substations for a given power demand
Explanation: Simple transformer step-down/step-up, enabling fewer, more widely spaced substations for a given power demand — verified fact for Railway Electrical Engineering Group B LDCE.
221. On sections with 25kV AC traction, feeder stations draw power from the state/regional electricity grid typically at:
- A. Directly from solar panels mounted on the OHE masts
- B. Only from small diesel generators located at the station
- C. From the locomotive's own onboard batteries
- D. A high-voltage transmission/sub-transmission level, which is then stepped down by the traction transformer
Answer: A high-voltage transmission/sub-transmission level, which is then stepped down by the traction transformer
Explanation: A high-voltage transmission/sub-transmission level, which is then stepped down by the traction transformer — verified fact for Railway Electrical Engineering Group B LDCE.
222. India's railway electrification uses single-phase 25kV AC (rather than three-phase) supply to the OHE mainly because:
- A. A single overhead contact wire system is simpler and more practical to construct and maintain along a linear track than a multi-wire three-phase system
- B. DC supply is not technically feasible over long distances
- C. AC single-phase cannot be rectified onboard the locomotive
- D. Three-phase supply cannot be transformed to any other voltage
Answer: A single overhead contact wire system is simpler and more practical to construct and maintain along a linear track than a multi-wire three-phase system
Explanation: A single overhead contact wire system is simpler and more practical to construct and maintain along a linear track than a multi-wire three-phase system — verified fact for Railway Electrical Engineering Group B LDCE.
223. One widely cited real benefit of railway electrification over diesel traction is:
- A. Complete elimination of any need for maintenance staff
- B. Automatic elimination of all signalling requirements
- C. Ability to run trains without any power supply infrastructure
- D. Lower operating cost per unit of haulage along with reduced dependence on imported crude oil
Answer: Lower operating cost per unit of haulage along with reduced dependence on imported crude oil
Explanation: Lower operating cost per unit of haulage along with reduced dependence on imported crude oil — verified fact for Railway Electrical Engineering Group B LDCE.
224. Indian Railways' large-scale main-line electrification programme has, over recent decades, primarily aimed to replace which older form of traction to reduce diesel fuel dependence?
- A. Diesel traction
- B. Battery-electric traction
- C. Steam traction only, with no relevance to diesel
- D. Hydrogen fuel-cell traction
Answer: Diesel traction
Explanation: Diesel traction — verified fact for Railway Electrical Engineering Group B LDCE.
225. Polymer (composite) insulators are increasingly used in modern OHE installations mainly due to their advantage of:
- A. Ability to carry traction current directly
- B. Elimination of the need for any insulation
- C. Lighter weight and good performance in polluted/contaminated environments compared to conventional porcelain
- D. Higher electrical conductivity than copper
Answer: Lighter weight and good performance in polluted/contaminated environments compared to conventional porcelain
Explanation: Lighter weight and good performance in polluted/contaminated environments compared to conventional porcelain — verified fact for Railway Electrical Engineering Group B LDCE.
226. Porcelain and toughened glass have traditionally been used as insulator materials in OHE mainly because they offer:
- A. Ability to generate voltage
- B. Very high electrical conductivity
- C. Magnetic properties needed for traction motors
- D. High dielectric strength along with good weathering and mechanical durability
Answer: High dielectric strength along with good weathering and mechanical durability
Explanation: High dielectric strength along with good weathering and mechanical durability — verified fact for Railway Electrical Engineering Group B LDCE.
227. The insulators used to mount OHE contact and catenary wires on masts/brackets must primarily provide:
- A. Signal transmission for interlocking
- B. Electrical insulation between the live OHE conductors and the earthed structure, with adequate mechanical strength
- C. Cooling for the traction motors
- D. Additional current-carrying capacity
Answer: Electrical insulation between the live OHE conductors and the earthed structure, with adequate mechanical strength
Explanation: Electrical insulation between the live OHE conductors and the earthed structure, with adequate mechanical strength — verified fact for Railway Electrical Engineering Group B LDCE.
228. A Paralleling Post (PP) in the traction OHE feeding arrangement is used to:
- A. Generate reactive power locally without any switchgear
- B. Disconnect the OHE from the grid completely at night
- C. Electrically connect (parallel) the up and down line OHE while keeping them on the same phase/feed, improving supply reliability
- D. Convert AC supply to DC for the OHE
Answer: Electrically connect (parallel) the up and down line OHE while keeping them on the same phase/feed, improving supply reliability
Explanation: Electrically connect (parallel) the up and down line OHE while keeping them on the same phase/feed, improving supply reliability — verified fact for Railway Electrical Engineering Group B LDCE.
229. A Sub-Sectioning Post (SSP) is generally located roughly midway between which two points on an electrified section?
- A. The traction substation and the sectioning post (or between two sectioning posts)
- B. Two adjacent railway stations only, regardless of substations
- C. Two signal cabins only
- D. Two diesel loco sheds
Answer: The traction substation and the sectioning post (or between two sectioning posts)
Explanation: The traction substation and the sectioning post (or between two sectioning posts) — verified fact for Railway Electrical Engineering Group B LDCE.
230. A Sectioning Post (SP) on an electrified railway section is primarily used to:
- A. Generate additional traction power locally
- B. Electrically sectionalize the OHE so that a faulty section can be isolated without affecting the whole feeding zone
- C. Store spare pantographs for locomotives
- D. House the divisional signalling control room
Answer: Electrically sectionalize the OHE so that a faulty section can be isolated without affecting the whole feeding zone
Explanation: Electrically sectionalize the OHE so that a faulty section can be isolated without affecting the whole feeding zone — verified fact for Railway Electrical Engineering Group B LDCE.
231. A traction substation on an electrified section primarily performs which basic function?
- A. Controlling signal interlocking logic
- B. Stepping down high-voltage grid supply and feeding 25kV single-phase power to the OHE
- C. Generating electricity from diesel engines
- D. Storing water for steam locomotives
Answer: Stepping down high-voltage grid supply and feeding 25kV single-phase power to the OHE
Explanation: Stepping down high-voltage grid supply and feeding 25kV single-phase power to the OHE — verified fact for Railway Electrical Engineering Group B LDCE.
232. The current-collecting device mounted on the roof of an electric locomotive that touches the contact wire is called the:
- A. Isolator
- B. Rheostat
- C. Circuit breaker
- D. Pantograph
Answer: Pantograph
Explanation: Pantograph — verified fact for Railway Electrical Engineering Group B LDCE.
233. The contact wire in OHE is deliberately given a zig-zag alignment along the track mainly to:
- A. Reduce the total length of wire required
- B. Ensure even wear across the pantograph contact strip instead of wearing a groove in one spot
- C. Reduce the weight of the mast
- D. Increase the traction voltage
Answer: Ensure even wear across the pantograph contact strip instead of wearing a groove in one spot
Explanation: Ensure even wear across the pantograph contact strip instead of wearing a groove in one spot — verified fact for Railway Electrical Engineering Group B LDCE.
234. The OHE component that holds the contact wire in its correct lateral (zig-zag) position relative to the track centre line is the:
- A. Dropper
- B. Registration arm (steady arm)
- C. Return conductor
- D. Catenary wire
Answer: Registration arm (steady arm)
Explanation: Registration arm (steady arm) — verified fact for Railway Electrical Engineering Group B LDCE.
235. The vertical members connecting the catenary wire to the contact wire at regular intervals in OHE are called:
- A. Droppers
- B. Registration arms
- C. Steady arms
- D. Anchor rods
Answer: Droppers
Explanation: Droppers — verified fact for Railway Electrical Engineering Group B LDCE.
236. In a conventional simple catenary OHE, the wire suspended above the contact wire that supports it at intervals is known as the:
- A. Contact wire
- B. Catenary or messenger wire
- C. Return conductor
- D. Feeder wire
Answer: Catenary or messenger wire
Explanation: Catenary or messenger wire — verified fact for Railway Electrical Engineering Group B LDCE.
237. In the overhead equipment (OHE) system, the wire that is in direct sliding contact with the pantograph is called the:
- A. Registration arm
- B. Contact wire
- C. Dropper
- D. Catenary (messenger) wire
Answer: Contact wire
Explanation: Contact wire — verified fact for Railway Electrical Engineering Group B LDCE.
238. Indian Railways' standard main-line traction electrification system uses AC power supply at what nominal voltage?
- A. 3 kV DC
- B. 11 kV three-phase AC
- C. 25 kV single-phase AC
- D. 1.5 kV DC
Answer: 25 kV single-phase AC
Explanation: 25 kV single-phase AC — verified fact for Railway Electrical Engineering Group B LDCE.
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