Operator - Question And Answer Key

Name of Post: Operator

Department: Kerala Water Authority

Cat. Number: 211/2020

Date of Test:04.02.2022

Question Code: 008/22


1. The unit of solid angle is :
(A) radian
(B) steradian
(C) degree
(D) none of the above

3. Melting point of copper is :
(A) 1083°C
(B) 1183°C
(C) 983°C
(D) 1000°C

4. One ampere-hour is equal to :
(A) 36000 coulombs
(B) 3600 coulombs
(C) 360 coulombs
(D) 36 coulombs

5. The shape of warning sign is ________.
(A) circular
(B) square
(C) triangular
(D) rectangular

6. Unit of M.M.F. is :
(A) Maxwell
(B) Lambda
(C) Joule
(D) Ampere turns

7. What is the permeability of bismuth ?
(A) 0.00099988
(B) 0.99988
(C) 1.000999881  
(D) 1.99988

8. The lifting power of a magnet is :
(A) A²A/2μ0
(B) B²B/2μ0
(C) A²A/4μ0
(D) B²B/4μ0

9. Which type of capacitors are used in RF coupling circuits ?
(A) tantalum
(B) electrolytic
(C) monolithic
(D) metalized polypropylene

10. The voltage of a simple voltaic cell is :
(A) 1.5V
(B) 1.28V
(C) 1.08V
(D) 1.4V

11. The speed of electricity is :
(A) 2,97,842 km/s
(B)  2,97,842 km/m
(C) 2,97,842 km/hr
(D) none of the above

12. What is the resistance of the inductive coil takes 5 A current across 240 V, 50 Hz supply at 0.8 P.F.?
(A) 48W
(B) 42.5 W
(C) 38.4W
(D) 26.6W

13. In a 3 phase system, if the active power is 4 kW and the apparent power is 5 kVA, calculate the reactive power.
(A) 1kVAR
(B) 2kVAR
(C) 3 kVAR
(D) 4kVAR

14. What is the di-electric strength in k.V/m.m. of asbestos at 20°C ?
(A) 40
(B) 42
(C) 44
(D) 46

15. Two wattmeter method is used to measure the power in _______ load.
(A) resistive load
(B) balanced load
(C) un-balanced load
(D) balanced and un-balanced load

16. To magnetize a steel is difficult because of its :
(A) high density
(B) high retentivity
(C) high permeability
(D) low permeability

17. What is the effect if one cell is connected with reverse polarity in a parallel combination circuit ?
(A) voltage became zero
(B) became open circuit
(C) will get short circuited
(D) no effect will function normally

19. Two batteries each of open circuit voltage 2 V and internal resistance of 2 ohm are connected in parallel to supply a load of 2 ohm the current supplied by the battery is :
(A) 0.33A
(B) 2A
(C) 0.8A
(D) 1A

20. A 24 ohm and 8 ohm resistors are in parallel have a combined resistance of :
(A) 32 ohm
(B) 24 ohm
(C) 12 ohm
(D) 60 ohm

21. The control force employed in an indicating instrument, which can be kept in any position is :
(A) gravity control
(B) eddy current control
(C) fluid friction control
(D) spring control

22. If the meter constant mentioned in the meter is 1500 revolution/k.W.H., in one revolution, the energy consumption is :
(A) 40 watt-minutes
(B) 60 watt-minutes
(C) 100 watt-minutes
(D) 50 watt-minutes

23. Maxwell-Wein bridge is used for measuring :
(A) capacitance
(B) dielectric loss
(C) inductance
(D) phase angle

24. The line voltage of a delta-connected three-phase circuit is 415 V. The phase voltage is:
(A) 220V
(B) 230V
(C) 240V
(D) 415 V

25. In a 3 phase star connected resistive load the resistance of each phase is 50 ohm if one of the resistances is removed and 200 V supply is given the absorbed power will be :
(A) 200W
(B) 400 W
(C) 800W
(D) 600 W

26. In Flemings left hand rule, forefinger indicates :
(A) Direction of supply of voltage
(B) Motion of the conductor
(C) Direction of field
(D) Direction of current flow

27. A current transformer step up :
(A) Voltage
(B) Current
(C) Power
(D) Frequency

28. Hunting occurs in :
(A) Transformer
(B) Induction motor
(C) Synchronous motor
(D) D.C. motor

29. The system earthing is done at :
(A) Domestic wiring
(B) Godown wiring
(C) Generating station
(D) House wiring

30. An example of cold cathode lamp is :
(A) Neon lamp
(B) Mercury vapour lamp
(C) Fluorescent tube
(D) Incandescent lamp

31. Decimal equivalent of Hexadecimal number ‘D’ is :
(A) 4
(B) 13
(c) 12
(D) 10

32. Terminals of a IGBT are :
(A) Base, Collector, Emitter
(B) Emitter, Collector, Gate
(C) Base 1, Base 2, Emitter
(D) Drain, Source, Gate

33. The capacity of Transformers are rated by its :
(A) True power
(B) Actual power
(C) Apparent power
(D) Reactive power

34. Which circuits quick response type diazed fuses are used ?
(A) Motor circuits
(B) Heating circuits
(C) Lightning circuits
(D) Electronics circuits

35. How many number of brushes are used in wave wound DC shunt generator ?
(A) 1
(B) 2
(C) 3
(D) 6

36. A JFET is a ________driven device.
(A) Voltage
(B) Current
(C) Frequency
(D) Power

37. The radix of decimal number system is :
(A) 1
(B) 2
(C) 10
(D) 0

38. As per BIS the shunt field winding terminals of a DC machine is marked :
(A) Bl & B2
(B) E1& E2

(C) FI& F2
(D) DI & D2

39. The V-curve of a synchronous motor is the relation between :
(A) Applied voltage and back emf
(B) Back emf and armature current
(C) Back emf and power factor
(D) Armature current & rotor field current

40. Which transformer does not step up or step down the voltage ?
(A) Auto transformer
(B) Isolation transformer
(C) Power transformer
(D) Current transformer

41. Binary value of 0101 is equivalent to decimal number :
(A) 5
(B) 7
(C) 4
(D) 3

42. An SCR ________ has semiconductor layers.
(A) 1
(B) 2
(C) 4
(D) 3

43. Ripple frequency of full wave bridge rectifier is :
(A) F input
(B) 2 F input
(C) 4F input
(D) yy F input

44. Which method of speed control is used to obtain above normal speed in DC series motor ?
(A) Field taping method
(B) Voltage control method
(C) Field diverter method
(D) Armature control method

45. Which one is a Universal gate ?
(A) OR

46. A UJT contains_________ PN junctions.
(A) 1
(B) 2
(C) 3
(D) 4

47. The insulation resistance of a DC motor is measured in :
(A) Mega volts
(B) Mega watts
(C) Mega ohms
(D) Kilo ohms

48. Which test is used to check whether the switches are connected in live wire or not ?
(A) Continuity test
(B) Open circuit test
(C) Ground test
(D) Polarity test

49. Which electrical accessories is used for taking supply from a lamp holder ?
(A) Ceiling rose
(B) 3 pin plug top
(C) Adaptor
(D) Two pin plug top

50. An example of invertor gate is :
(B) OR

51. What is the purpose of soldering on sheet metal joint ?
(A) To avoid bend
(B) To avoid crack
(C) To avoid leak
(D) To make strengthless

52. Which part in the internal gear pump act as seal ?
(A) Gears
(B) Gasket
(C) Sealing ring
(D) Cresent shaped spacer

53. Which rivet used in heavy structural work ?
(A) Pan head rivet
(B) Snap head rivet
(C) Counter sunk rivet
(D) Conical head rivet

54. Which washers are commonly used for structural fabrication work ?
(A) Flat washers
(B) Punched washers
(C) Tab washer
(D) Toothed lock washer

55. Which metal is very soft and heavy in sheet metal work ?
(A) Lead
(B) Black iron
(C) Aluminium
(D) Copper sheet

56. Which hammer is suitable for riveting ?
(A) Plastic hammer
(B) Ball pein hammer
(C) Cross pein hammer
(D) Straight pein hammer

57. Which key is used for easy fixing and removing ?
(A) Feather key
(B) Gib-head key
(C) Hollow saddle key
(D) Circular taper key

58. Which type of nut required aligning the axle shaft hole and slot of the nut for locking ?
(A) Castle nut
(B) Chuck nut
(C) Thumb nut
(D) Self lock nut

59. Which energy is converted in hydraulic pump ?
(A) Thermal energy to hydraulic energy
(B) Electrical energy to hydraulic energy
(C) Pneumatic energy to hydraulic energy
(D) Mechanical energy to hydraulic energy

60. Which type of filter helps to protect the pump from fluid contaminations ?
(A) Suction filter
(B) Magnetic filter
(C) Absorbent filter
(D) Mechanical filter

61. Which of the following is an insulator ?
(A) Copper
(B) Aluminium
(C) Silver

62. Which is a good conductor ?
(A) Silver
(B) Iron
(C) Steel
(D) Aluminium

63. Which law states that “The current is directly proportional to the voltage and inversely proportional to the resistance” ?
(A) Ohm’s law
(B) Hook’s law
(C) Boyle’s law
(D) Newton's law

64. What is the material of negative plate in the lead acid battery ?
(A) Antimony
(B) Tin
(C) Spongy lead
(D) Lead peroxide

65. Which instrument is prohibited to connect with live wire ?
(A) Ammeter
(B) Voltmeter
(C) Ohm meter
(D) Watt meter

66. Which measuring instrument used to measure the ampere, volt and resistance ?
(A) Watt meter
(B) Energy meter
(C) Galvano meter
(D) Multi meter

67. What is the unit of potential difference ?
(A) Watt
(B) Ampere
(C) Ohm
(D) Volts

68. What is the advantage of free maintenance sealed battery ?
(A) No need for check and top up distilled water
(B) No need for recharging the battery
(C) No chance of sulphation of battery terminals
(D) No need of disconnect the terminals to remove battery

69. Which is a temperature sensitive resistor ?
(A) Diode
(B) Thyristor
(C) Thermistor
(D) Transistor

70. Which circuit the ballast resistor is used ?
(A) Horn circuit
(B) Wiper circuit
(C) Flasher circuit
(D) Headlamp circuit

71. Which of the following is true about the thermodynamic cycle of a diesel engine ?
(A) Constant volume cycle
(B) Constant pressure cycle
(C) Atkinson cycle
(D) None of these

72. What is the range of compression pressure of a typical petrol engine ?
(A) 90 to 150 PSI
(B) 400 to 550 PSI
(C) 500 to 700 PSI
 (D) None of these

73. Which of the following is false about engine cooling system ?
(A) Radiator pressure cap consists of a pressure valve which opens up when the pressure exceeds a pre-set value.
(B) Vacuum valve on radiator pressure cap opens up to let the coolant in while the engine cools down.
(C) ECM calculates coolant temperature value from the ECT sensor output.
(D) Engine overheats if the thermostat valve is stuck open.

74. In which of the following types of oil pumps does not use eccentric shafts or cams ?
(A) External gear type pump
(B) Rotor type pump
(C) Vane type pump
(D) Plunger type pump

75. Which of the following statements is false about lubrication system ?
(A) Oil cooler heats the oil when coolant temperature is greater than oil temperature.
(B) All the oil reaching main oil gallery is filtered in Bypass oil filter system.
(C) Dry sump lubrication system uses a separate tank to store oil.
(D) Lubricant also helps in preventing blow by gases entering crankcase.

76. Which of the following is false about fuel system ?
(A) Air locking in the diesel fuel system will cause erratic running of engine.
(B) Water in fuel system might damage fuel injectors.
(C) An engine can be started without the signal from Crank position sensor (CKP) input.
(D) Injection pressure in CRDi engines vary from 200 to 2000 bars.

77. Which of the following type of pump needs more frequent overhaul frequency than others under similar operating conditions ?
(A) Submersible pump
(B) Vertical turbine pump
(C) Centrifugal pumps
(D) All of these pumps have broadly the same maintenance frequency

78. Which of the following is true about the Submersible pumps ?
(A) Single stage pumps are preferred over Multistage pumps in water wells and oil wells
(B) They are centrifugal pumps operating in a vertical position
(C) The energy conversion taking place at the pump diffuser is kinetic energy into pressure energy
(D) All are true

79. Which of the following is false about Jet pumps ?
(A) It has no reciprocating parts
(B) The motor and pump cannot be offset from the well
(C) Suction pipe is connected to the nozzle chamber
(D) All are false

80. Which of the following is wrong ?
(A) A locked pump shaft will result in blown pump fuse
(B) Clogged strainer will result in reduced pump capacity
(C) A leaking valve will cause rapid wear and tear on parts
(D) Faulty pressure switch will result in pump not starting up

81. Crowning of pulleys are done for :
(A) Better belt life
(B) Lesser chance of belt running off
(C) Less belt slips
 (D) None of these

82. Which of the following is not true about induction motors ?
(A) Rotor of the induction motor cannot run at synchronous speed.
(B) Motor r.p.m. increases with frequency of input supply
(C) Low rotor resistance means high starting torque
(D) Direction of rotation of an induction motor can be changed by any two swapping phase leads

83. Which type of valve is used for very fine control of fluid flow ?
(A) Butterfly valve
(B) Angle valve
(C) Ball valve
(D) Needle valve

84. Which of the following starters are used for starting a squirrel cage motor ?
(A) Star-delta starter
(B) Auto-transformer starter
(C) Step-down transformer
(D) All of these

85. Which of the following is false about D.O.L starters ?
(A) No-volt coil disconnects supply to the motor when the supply voltage is lower
(B) A thermal overload relay is provided to protect the motor
(C) Can be used without backup fuses
(D) Due to heavy starting current, their usage is limited beyond a certain motor capacity

86. Which of the following are the features of an ELCB, MCB Circuit breaker ?
(A) Over current
(B) Short circuit
(C) Earth leakage
(D) All of these

87. What is cut-off factor of a fuse ?
(A) The current at which the fuse element melts
(B) Ratio between minimum fusing current and current rating
(C) The voltage at which fuse element melts
(D) Time taken by a fuse to interrupt the circuit in the event of a fault

88. To what limit of current beyond which Re-wirable fuses are not usually preferred ?
(A) 200A
(B) 350A
(C) 500A
(D) 1250A

89. Which of the following relays designed to operate when current falls below a predetermined value ?
(A) Electromagnetic relay
(B) Current sensing relay
(C) Under-current relay
(D) Latching relays

90. Which of the following is not a reason of motor running hot ?
(A) Open circuit winding
(B) Short circuited capacitor
(C) Defective capacitor
(D) Blown fuse

91. Inside which of the following hydraulic pumps a crescent shaped spacing can be found ?
(A) External gear pump
(B) Internal gear pump
(C) Vane type pump
(D) Lobe pump

92. Which of the following is true about temperature sensors ?
(A) Its electrical resistance increases with increase in temperature
(B) Its electrical resistance decreases with increase in temperature
(C) It could be fitted with a balancing coil gauge
(D) Its electrical resistance remains unchanged irrespective of temperature changes

93. Which of the following components serves the purpose of retaining the piston down against the seat in balanced condition in a pressure relief valve ?
(A) Heavy spring
(B) Poppet
(C) Adjusting screw
(D) Light spring

94. Which of the following is a dependant factor on fluid flow rate of a variable flow control valve ?
(A) Pressure difference
(B) The size of throttle gap
(C) Viscosity of oil
(D) All of these

95. Which of the following is not true about pneumatic systems ?
(A) FRL assembly also add small quantities of oil into the compressed air systems
(B) The expansion of PRV is Pressure Return Valve
(C) Pressure switch can restart the compressor motor when the pressure drops below a pre-set value
(D) Spool valve is a type of slide valve

96. Which of the following is false about Orifices ?
(A) An orifice is the simplest method for controlling fluid flow
(B) The orifice is always connected in parallel with the pump
(C) Variable orifice is a calibrated needle valve
(D) Orifices create a pressure drop

97. Which of the following is not associated with hydraulic actuator speed control ?
(A) Meter in speed control
(B) Meter out speed control
(C) Bleed off speed control
(D) Bleed out speed control

98. Which one of the following terms is associated with positive displacement pumps ?
(A) Volute casing
(B) Semi open impeller
(C) Turbine pump
(D) Screw rotors

99. Which of the following is not related with pipe joints ?
(A) Eccentric reducer
(B) Concentric reducer
(C) Short nipple
(D) Flanged bush

100. Which of the following is not true about pumps ?
(A) Rotary pumps don’t need to be primed
(B) Increase in fluid temperature causes cavitation
(C) Foot valves are non-return valves
(D) Self priming devices are connected between discharge pipe and pump

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