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<\/a><\/figure>\n\n\n\nHow to Practise These Electrical Engineering PYQs<\/h2>\n\n\n\n
Attempt each question before reading its answer. For numerical problems, write the formula and convert quantities to consistent units first. After checking the explanation, revise the concept behind any incorrect answer.<\/p>\n\n\n\n
Q1. Above its resonant frequency, how does a series RLC circuit behave?<\/h3>\n\n\n\n
A. Inductively
B. Capacitively
C. Resistively
D. Either inductively or capacitively<\/p>\n\n\n\n
Correct Answer:<\/strong> A. Inductively<\/p>\n\n\n\nExplanation:<\/strong> Above resonance, inductive reactance exceeds capacitive reactance. The net reactance is therefore inductive.<\/p>\n\n\n\nQ2. For maximum AC power transfer, what load impedance should match a source impedance Z?<\/h3>\n\n\n\n
A. The real component of Z
B. Z\/2
C. Z itself
D. The complex conjugate Z*<\/p>\n\n\n\n
Correct Answer:<\/strong> D. The complex conjugate Z*<\/p>\n\n\n\nExplanation:<\/strong> Conjugate matching cancels the source reactance and matches the load resistance to the source resistance.<\/p>\n\n\n\nQ3. Three 9 \u03a9 resistors form a delta. What is each resistance in the equivalent star?<\/h3>\n\n\n\n
A. 18 \u03a9
B. 6 \u03a9
C. 3 \u03a9
D. 4.5 \u03a9<\/p>\n\n\n\n
Correct Answer:<\/strong> C. 3 \u03a9<\/p>\n\n\n\nExplanation:<\/strong> For three equal delta resistances, each equivalent star resistance is one-third of the delta resistance:\\[ R_Y=\\frac{R_\\Delta}{3}=\\frac{9}{3}=3\\ \\Omega \\]<\/p>\n\n\n\nQ4. According to Lenz\u2019s law, what does the induced EMF oppose?<\/h3>\n\n\n\n
A. Magnetic flux
B. A change in magnetic flux
C. Both flux and its change
D. Neither of these<\/p>\n\n\n\n
Correct Answer:<\/strong> B. A change in magnetic flux<\/p>\n\n\n\nExplanation:<\/strong> The induced effect opposes the change in magnetic flux that produces it. It does not necessarily oppose the existing flux itself.<\/p>\n\n\n\nQ5. A 5 cm coil has 10 turns carrying 1.5 A. Find its magnetising force.<\/h3>\n\n\n\n
A. 150 AT\/m
B. 600 AT\/m
C. 450 AT\/m
D. 300 AT\/m<\/p>\n\n\n\n
Correct Answer:<\/strong> D. 300 AT\/m<\/p>\n\n\n\nExplanation:<\/strong> Using \\(H=NI\/l\\):\\[ H=\\frac{10\\times1.5}{0.05}=300\\ \\text{AT\/m} \\]<\/p>\n\n\n\nThe coil length must be converted from centimetres to metres.<\/p>\n\n\n\n
Q6. How many segments make up the usual LED digit display of a digital multimeter?<\/h3>\n\n\n\n
A. 6
B. 8
C. 7
D. 9<\/p>\n\n\n\n
Correct Answer:<\/strong> C. 7<\/p>\n\n\n\nExplanation:<\/strong> Seven controlled segments form the numerical digits. A decimal point, where present, is separate from these seven segments.<\/p>\n\n\n\nQ7. What is the purpose of an explosion vent on a power transformer?<\/h3>\n\n\n\n
A. Releasing air
B. Releasing moisture
C. Relieving pressure
D. Relieving overload<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Relieving pressure<\/p>\n\n\n\nExplanation:<\/strong> The vent releases excessive internal pressure that may develop during a serious internal fault.<\/p>\n\n\n\nQ8. Which diode has a negative-resistance region in its characteristic?<\/h3>\n\n\n\n
A. A rectifier diode
B. A tunnel diode
C. A Zener diode
D. A PIN diode<\/p>\n\n\n\n
Correct Answer:<\/strong> B. A tunnel diode<\/p>\n\n\n\nExplanation:<\/strong> In part of a tunnel diode\u2019s characteristic, current decreases as voltage increases. This is called negative differential resistance.<\/p>\n\n\n\nQ9. Which steam-power-plant device heats boiler feedwater using heat recovered from flue gases?<\/h3>\n\n\n\n
A. Air preheater
B. Economiser
C. Superheater
D. Feedwater heater<\/p>\n\n\n\n
Correct Answer:<\/strong> B. Economiser<\/p>\n\n\n\nExplanation:<\/strong> An economiser transfers waste heat from flue gases to feedwater before it enters the boiler.<\/p>\n\n\n\nQ10. What does ACSR stand for?<\/h3>\n\n\n\n
A. All Conductors Selected Reinforced
B. Aluminium Conductor Steel Reinforced
C. All Conductors Steel Reinforced
D. Aluminium Conductor Selected Reinforced<\/p>\n\n\n\n
Correct Answer:<\/strong> B. Aluminium Conductor Steel Reinforced<\/p>\n\n\n\nExplanation:<\/strong> Aluminium carries the current, while the steel core provides mechanical strength.<\/p>\n\n\n\nBatteries, Solar Cells and DC Motor Braking<\/h2>\n\n\n\nQ11. What is the nominal voltage of one standard lead-acid cell?<\/h3>\n\n\n\n
A. 1.2 V
B. 1.5 V
C. 2 V
D. 6 V<\/p>\n\n\n\n
Correct Answer:<\/strong> C. 2 V<\/p>\n\n\n\nExplanation:<\/strong> One lead-acid cell is nominally 2 V. Three cells connected in series form a nominal 6 V battery.<\/p>\n\n\n\nQ12. Which listed material is used to manufacture solar cells?<\/h3>\n\n\n\n
A. Carbon
B. Magnesium
C. Sodium
D. Silicon<\/p>\n\n\n\n
Correct Answer:<\/strong> D. Silicon<\/p>\n\n\n\nExplanation:<\/strong> Silicon is the semiconductor used in conventional crystalline solar cells.<\/p>\n\n\n\nQ13. Into which form of energy does a solar cell convert light?<\/h3>\n\n\n\n
A. Heat
B. Electrical energy
C. Chemical energy
D. Sound<\/p>\n\n\n\n
Correct Answer:<\/strong> B. Electrical energy<\/p>\n\n\n\nExplanation:<\/strong> Photovoltaic action converts absorbed light directly into electrical energy.<\/p>\n\n\n\nQ14. Which material forms the filament of an incandescent lamp?<\/h3>\n\n\n\n
A. Tungsten
B. Copper
C. Thorium
D. Titanium<\/p>\n\n\n\n
Correct Answer:<\/strong> A. Tungsten<\/p>\n\n\n\nExplanation:<\/strong> Tungsten withstands the high temperature needed for the filament to emit visible light.<\/p>\n\n\n\nQ15. Which operating method reverses the supply voltage of a separately excited DC motor?<\/h3>\n\n\n\n
A. Forward motoring
B. Forward regenerative braking
C. Forward dynamic braking
D. Forward plugging<\/p>\n\n\n\n
Correct Answer:<\/strong> D. Forward plugging<\/p>\n\n\n\nExplanation:<\/strong> Reversing the armature supply while maintaining field polarity produces braking torque. The original paper\u2019s typo \u201crevered\u201d has been corrected to \u201creversed.\u201d<\/p>\n\n\n\nQ16. What principle enables a two-winding transformer to work?<\/h3>\n\n\n\n
A. Self-induction
B. Mutual induction
C. Electromagnetic drag
D. Conduction<\/p>\n\n\n\n
Correct Answer:<\/strong> B. Mutual induction<\/p>\n\n\n\nExplanation:<\/strong> Changing primary current creates magnetic flux linking the secondary winding and induces voltage in it.<\/p>\n\n\n\nQ17. Which quantity remains unchanged during transformer action?<\/h3>\n\n\n\n
A. Current
B. Voltage
C. Frequency
D. Temperature<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Frequency<\/p>\n\n\n\nExplanation:<\/strong> A transformer changes voltage and current levels, but its output frequency equals the input frequency.<\/p>\n\n\n\nQ18. Which unit expresses \u201clamp efficiency\u201d in the question\u2019s terminology?<\/h3>\n\n\n\n
A. Lumen-second
B. Lumen
C. Lumen per watt
D. Lux<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Lumen per watt<\/p>\n\n\n\nExplanation:<\/strong> The precise term is luminous efficacy: luminous flux divided by electrical input power, measured in lm\/W.<\/p>\n\n\n\nQ19. If the distance from a light source doubles, what happens to illumination?<\/h3>\n\n\n\n
A. It doubles
B. It quadruples
C. It halves
D. It becomes one-quarter<\/p>\n\n\n\n
Correct Answer:<\/strong> D. It becomes one-quarter<\/p>\n\n\n\nExplanation:<\/strong> For a point source with unchanged incidence angle, illumination follows the inverse-square law:\\[ E\\propto\\frac{1}{r^2} \\]<\/p>\n\n\n\nDoubling the distance reduces illumination to one-quarter.<\/p>\n\n\n\n
Q20. What is the ripple factor of a single-phase full-wave bridge rectifier?<\/h3>\n\n\n\n
A. 0.482
B. 0.812
C. 1.11
D. 1.21<\/p>\n\n\n\n
Correct Answer:<\/strong> A. 0.482<\/p>\n\n\n\nExplanation:<\/strong> This is the conventional approximate value for an ideal, unfiltered full-wave output with a resistive load. Adding a filter changes the ripple factor.<\/p>\n\n\n\nQ21. Varying field flux for speed control gives which type of drive?<\/h3>\n\n\n\n
A. Variable-torque drive
B. Variable-power drive
C. Constant-torque drive
D. Constant-power drive<\/p>\n\n\n\n
Correct Answer:<\/strong> D. Constant-power drive<\/p>\n\n\n\nExplanation:<\/strong> In the usual DC field-weakening region, speed rises while available torque falls, giving approximately constant-power operation.<\/p>\n\n\n\nQ22. When does an induction motor operate with a lagging power factor?<\/h3>\n\n\n\n
A. Only while starting
B. Only while running
C. During starting and running
D. When stationary<\/p>\n\n\n\n
Correct Answer:<\/strong> C. During starting and running<\/p>\n\n\n\nExplanation:<\/strong> An ordinary induction motor draws inductive magnetising current during both starting and running.<\/p>\n\n\n\nQ23. What input and output impedances should an ideal voltage amplifier have?<\/h3>\n\n\n\n
A. Low input; high output
B. High input; high output
C. Low input; low output
D. High input; low output<\/p>\n\n\n\n
Correct Answer:<\/strong> D. High input; low output<\/p>\n\n\n\nExplanation:<\/strong> Ideally, infinite input impedance avoids source loading, while zero output impedance maintains the output voltage under load.<\/p>\n\n\n\nQ24. What role does a DIAC perform in a power-control circuit?<\/h3>\n\n\n\n
A. Rectification
B. Triggering
C. Oscillation
D. Amplification<\/p>\n\n\n\n
Correct Answer:<\/strong> B. Triggering<\/p>\n\n\n\nExplanation:<\/strong> A DIAC commonly supplies bidirectional triggering pulses to a TRIAC in an AC power-control circuit.<\/p>\n\n\n\nQ25. Which unit supplies power internally in a computer?<\/h3>\n\n\n\n
A. CVT
B. UPS
C. SMPS
D. Stabiliser<\/p>\n\n\n\n
Correct Answer:<\/strong> C. SMPS<\/p>\n\n\n\nExplanation:<\/strong> A switched-mode power supply provides regulated DC outputs. The original uses \u201cCPU\u201d loosely for the computer system unit; this wording is clarified here.<\/p>\n\n\n\nQ26. What type of resistor is a varistor?<\/h3>\n\n\n\n
A. Linear resistor
B. Carbon resistor
C. Resistor having zero temperature coefficient
D. Nonlinear resistor<\/p>\n\n\n\n
Correct Answer:<\/strong> D. Nonlinear resistor<\/p>\n\n\n\nExplanation:<\/strong> A varistor\u2019s resistance changes with applied voltage. This property enables it to suppress voltage surges.<\/p>\n\n\n\nQ27. What is a circuit called when its properties are the same in either direction?<\/h3>\n\n\n\n
A. Unilateral circuit
B. Irreversible circuit
C. Bilateral circuit
D. Short circuit<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Bilateral circuit<\/p>\n\n\n\nExplanation:<\/strong> A bilateral circuit has the same characteristics when current direction is reversed.<\/p>\n\n\n\nQ28. Which substance serves as the depolariser in a Leclanch\u00e9 cell?<\/h3>\n\n\n\n
A. NH\u2084Cl
B. Mn\u2082O\u2083
C. MnO\u2082
D. KOH<\/p>\n\n\n\n
Correct Answer:<\/strong> C. MnO\u2082<\/p>\n\n\n\nExplanation:<\/strong> Manganese dioxide is the depolarising material. Ammonium chloride serves as the electrolyte.<\/p>\n\n\n\nQ29. What is the relative permeability of a diamagnetic material?<\/h3>\n\n\n\n
A. Below 1
B. Above 1
C. Above 100
D. Equal to that of a ferromagnetic material<\/p>\n\n\n\n
Correct Answer:<\/strong> A. Below 1<\/p>\n\n\n\nExplanation:<\/strong> A diamagnetic material has negative magnetic susceptibility, making its relative permeability slightly less than unity.<\/p>\n\n\n\nQ30. How many depletion layers does a bipolar junction transistor have?<\/h3>\n\n\n\n
A. Three
B. Two
C. One
D. Four<\/p>\n\n\n\n
Correct Answer:<\/strong> B. Two<\/p>\n\n\n\nExplanation:<\/strong> The emitter\u2013base and collector\u2013base junctions each have a depletion region.<\/p>\n\n\n\nQ31. A 50 Hz induction motor operates at 2% slip. What is its rotor-current frequency?<\/h3>\n\n\n\n
A. 50 Hz
B. 25 Hz
C. 2 Hz
D. 1 Hz<\/p>\n\n\n\n
Correct Answer:<\/strong> D. 1 Hz<\/p>\n\n\n\nExplanation:<\/strong> Rotor-current frequency equals slip multiplied by supply frequency:\\[ f_r=sf=0.02\\times50=1\\ \\text{Hz} \\]<\/p>\n\n\n\nQ32. A 200 V DC shunt motor develops 54 N\u00b7m at an armature current of 10 A. What torque will it develop at 20 A?<\/h3>\n\n\n\n
A. 108 N\u00b7m
B. 54 N\u00b7m
C. 216 N\u00b7m
D. 27 N\u00b7m<\/p>\n\n\n\n
Correct Answer:<\/strong> A. 108 N\u00b7m<\/p>\n\n\n\nExplanation:<\/strong> With approximately constant field flux, torque is proportional to armature current. Doubling the current doubles the torque:\\[ T_2=54\\times\\frac{20}{10}=108\\ \\text{N\u00b7m} \\]<\/p>\n\n\n\nQ33. A 400\/200 V, 5 kVA transformer has 200 W core loss and 800 W full-load copper loss. At what load is efficiency maximum?<\/h3>\n\n\n\n
A. 5 kVA
B. 4 kVA
C. 3.5 kVA
D. 2.5 kVA<\/p>\n\n\n\n
Correct Answer:<\/strong> D. 2.5 kVA<\/p>\n\n\n\nExplanation:<\/strong> Maximum efficiency occurs when copper loss equals core loss. If \\(x\\) is the fraction of full load:\\[ x=\\sqrt{\\frac{200}{800}}=0.5 \\]<\/p>\n\n\n\nTherefore, the required load is \\(0.5\\times5=2.5\\) kVA.<\/p>\n\n\n\n
Q34. Which power factors can a synchronous motor operate at?<\/h3>\n\n\n\n
A. Always lagging
B. Always leading
C. Leading, lagging or unity
D. Unity or lagging only<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Leading, lagging or unity<\/p>\n\n\n\nExplanation:<\/strong> Changing field excitation changes reactive-power demand, allowing operation at lagging, unity or leading power factor.<\/p>\n\n\n\nQ35. Why are dummy coils provided in a generator?<\/h3>\n\n\n\n
A. To decrease eddy-current loss
B. To increase flux density
C. To increase voltage
D. To maintain mechanical rotor balance<\/p>\n\n\n\n
Correct Answer:<\/strong> D. To maintain mechanical rotor balance<\/p>\n\n\n\nExplanation:<\/strong> Dummy coils maintain mechanical balance without taking part in the electrical winding circuit.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrical Engineer \u2014 Kerala State Cooperative Coir Marketing Federation Ltd, 7 June 2023<\/p>\n\n\n\nQ36. Which factors determine a battery\u2019s capacity?<\/h3>\n\n\n\n
A. Plate size and number
B. Amount of active material
C. Amount of electrolyte
D. All three<\/p>\n\n\n\n
Correct Answer:<\/strong> D. All three<\/p>\n\n\n\nExplanation:<\/strong> These construction factors influence how much charge the battery can deliver. Actual capacity also depends on operating conditions.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician \/ Overseer Grade I \/ Junior Instructor in Electrician, 30 September 2024
Paper:<\/strong> 129\/2024, booklet A, original Q44<\/p>\n\n\n\nQ37. On which motor should Swinburne\u2019s test not be performed?<\/h3>\n\n\n\n
A. DC shunt motor
B. DC series motor
C. Separately excited DC motor
D. It can be performed on every DC motor type<\/p>\n\n\n\n
Correct Answer:<\/strong> B. DC series motor<\/p>\n\n\n\nExplanation:<\/strong> Swinburne\u2019s is a no-load test. A DC series motor may accelerate dangerously when run without load.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician \/ Overseer Grade I \/ Junior Instructor in Electrician, 30 September 2024
Paper:<\/strong> 129\/2024, booklet A, original Q69<\/p>\n\n\n\nQ38. How does the starting torque of a three-phase induction motor depend on supply voltage?<\/h3>\n\n\n\n
A. It is independent of voltage
B. It is directly proportional to voltage
C. It is directly proportional to voltage squared
D. None of these<\/p>\n\n\n\n
Correct Answer:<\/strong> C. It is directly proportional to voltage squared<\/p>\n\n\n\nExplanation:<\/strong> At fixed frequency and machine parameters:\\[ T_{\\text{start}}\\propto V^2 \\]<\/p>\n\n\n\nA reduction in supply voltage therefore causes a larger proportional reduction in starting torque.<\/p>\n\n\n\n
Exam:<\/strong> Kerala PSC Electrician \/ Overseer Grade I \/ Junior Instructor in Electrician, 30 September 2024
Paper:<\/strong> 129\/2024, booklet A, original Q71<\/p>\n\n\n\nQ39. Which alternator type is used in a hydroelectric power station?<\/h3>\n\n\n\n
A. Non-salient-pole type
B. Turbo-generator
C. Steam turbine
D. Salient-pole type<\/p>\n\n\n\n
Correct Answer:<\/strong> D. Salient-pole type<\/p>\n\n\n\nExplanation:<\/strong> Salient-pole alternators suit the comparatively low speeds of hydro turbines and can accommodate many poles.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician \/ Overseer Grade I \/ Junior Instructor in Electrician, 30 September 2024
Paper:<\/strong> 129\/2024, booklet A, original Q75<\/p>\n\n\n\nQ40. All-day efficiency is especially useful for assessing which transformer?<\/h3>\n\n\n\n
A. Distribution transformer
B. Autotransformer
C. Power transformer
D. Two-winding transformer<\/p>\n\n\n\n
Correct Answer:<\/strong> A. Distribution transformer<\/p>\n\n\n\nExplanation:<\/strong> A distribution transformer operates at varying loads throughout the day. Its 24-hour energy efficiency is therefore particularly useful.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician \/ Overseer Grade I \/ Junior Instructor in Electrician, 30 September 2024
Paper:<\/strong> 129\/2024, booklet A, original Q76<\/p>\n\n\n\nQ41. In the two-wattmeter method, one meter reads zero and the other reads total power. What is the power factor?<\/h3>\n\n\n\n
A. 1
B. 0.5
C. Below 0.5
D. Zero<\/p>\n\n\n\n
Correct Answer:<\/strong> B. 0.5<\/p>\n\n\n\nExplanation:<\/strong> For a balanced three-phase load, one wattmeter reads zero at a phase angle of \\(60^\\circ\\):\\[ \\text{Power factor}=\\cos60^\\circ=0.5 \\]<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician\/Lineman, 26 September 2025
Paper:<\/strong> 121\/2025, booklet A, original Q62<\/p>\n\n\n\nQ42. Where is the oil-level indicator typically fitted on a distribution transformer?<\/h3>\n\n\n\n
A. Main tank
B. Conservator tank
C. Cooling tubes
D. Bushings<\/p>\n\n\n\n
Correct Answer:<\/strong> B. Conservator tank<\/p>\n\n\n\nExplanation:<\/strong> For a conventional conservator-equipped transformer, the indicator shows the oil level in the conservator. This does not describe every sealed transformer design.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician\/Lineman, 26 September 2025
Paper:<\/strong> 121\/2025, booklet A, original Q67<\/p>\n\n\n\nQ43. Which listed factor improves LED-light performance?<\/h3>\n\n\n\n
A. Ferroresonance
B. Customisation
C. Utility factor
D. Thermal management<\/p>\n\n\n\n
Correct Answer:<\/strong> D. Thermal management<\/p>\n\n\n\nExplanation:<\/strong> Effective heat removal limits LED junction temperature and supports light output and service life.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician\/Lineman, 26 September 2025
Paper:<\/strong> 121\/2025, booklet A, original Q73<\/p>\n\n\n\nQ44. What does COB stand for in electronics?<\/h3>\n\n\n\n
A. Chip on Board
B. Circuit on Board
C. Connection on Board
D. Capacitor on Board<\/p>\n\n\n\n
Correct Answer:<\/strong> A. Chip on Board<\/p>\n\n\n\nExplanation:<\/strong> Chip-on-board construction mounts semiconductor chips directly on a board or substrate.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician\/Lineman, 26 September 2025
Paper:<\/strong> 121\/2025, booklet A, original Q74<\/p>\n\n\n\nQ45. What functions does the condenser perform in a steam power plant?<\/h3>\n\n\n\n
A. Maintains very low pressure at the turbine exhaust
B. Provides condensate that can be reused as boiler feedwater
C. Performs both A and B
D. Performs neither<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Performs both A and B<\/p>\n\n\n\nExplanation:<\/strong> Condensation maintains low turbine-exhaust pressure and recovers water for reuse in the steam cycle.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician\/Lineman, 26 September 2025
Paper:<\/strong> 121\/2025, booklet A, original Q85<\/p>\n\n\n\nQ46. Which panel-board device protects a motor against overload and overheating?<\/h3>\n\n\n\n
A. Rectifier
B. Limit switch
C. Thermal relay
D. Electromechanical relay<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Thermal relay<\/p>\n\n\n\nExplanation:<\/strong> A thermal overload relay trips after sustained excessive current, protecting the motor against overheating.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician-cum-Mechanic \u2014 Medical Education Department, 20 July 2023
Paper:<\/strong> 118\/2023\/OL, original Q25<\/p>\n\n\n\nQ47. What is the function of a moderator in a nuclear reactor?<\/h3>\n\n\n\n
A. Absorbing excess neutrons
B. Increasing neutron energy
C. Slowing neutrons
D. Slowing electrons<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Slowing neutrons<\/p>\n\n\n\nExplanation:<\/strong> A moderator reduces neutron energy. Control rods primarily absorb neutrons to control the chain reaction.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician-cum-Mechanic \u2014 Medical Education Department, 20 July 2023
Paper:<\/strong> 118\/2023\/OL, original Q29<\/p>\n\n\n\nQ48. Which controller is used for an eddy-current drive?<\/h3>\n\n\n\n
A. Slip controller
B. Rectifier controller
C. AC-voltage controller
D. DC-chopper controller<\/p>\n\n\n\n
Correct Answer:<\/strong> A. Slip controller<\/p>\n\n\n\nExplanation:<\/strong> An eddy-current drive regulates output speed by controlling coupling excitation and slip.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician-cum-Mechanic \u2014 Medical Education Department, 20 July 2023
Paper:<\/strong> 118\/2023\/OL, original Q30<\/p>\n\n\n\nQ49. Which listed condition causes hunting in an alternator?<\/h3>\n\n\n\n
A. Operation with fluctuating speed
B. Overload
C. Continuous load fluctuations
D. No-load operation<\/p>\n\n\n\n
Correct Answer:<\/strong> C. Continuous load fluctuations<\/p>\n\n\n\nExplanation:<\/strong> Load disturbances cause rotor oscillations about the synchronous operating position. These oscillations are known as hunting.<\/p>\n\n\n\nExam:<\/strong> Kerala PSC Electrician-cum-Mechanic \u2014 Medical Education Department, 20 July 2023
Paper:<\/strong> 118\/2023\/OL, original Q40<\/p>\n\n\n\nQ50. Why must the load be disconnected before operating a transformer\u2019s off-load tap changer?<\/h3>\n\n\n\n
A. To disconnect the taps from the neutral point