[PDF Notes] What do you mean by Fiscal Policy of Inflation?

Fiscal policy is the budgetary policy of the government relating to taxes, public expenditure, public borrowing and deficit financing. The major anti-inflationary fiscal measures include (a) increase in taxation, (b) reduction in public expenditure, (c) increase in public borrowing, and (d) control of deficit financing.

1. Increase in Taxation:

Anti-inflationary tax policy should be directed towards restricting demand without restricting production.

Excise duties and sales tax on various goods, for example, take away the buying power from the consumer goods market without discouraging the expanding productive capacity of the economy.

Some economists, therefore, prefer progressive direct taxes because such taxes on the one hand, reduce the disposable income of the people and, on the other hand, are justified on the basis of social equity.

2. Reduction in Public Expenditure:

During inflation, effective demand is very high due to expansion of public and private spending. In order to check unregulated private spending, the government should first of all reduce its unproductive expenditure.

In fact, during inflation, at the full employment level, the effective demand in relation to the available supply of goods and services is reduced to extend that government expenditure is curtailed.

Public expenditure being autonomous, an initial reduction in it will lead to a multiple reduction in the total expenditure of the economy. But, there are certain limitations of this measure:

(a) It is not possible to reduce public expenditure related to defence needs particularly during war times.

(b) Heavy reduction in government expenditure may come into clash with the planned long-run investment programmes in a developing economy.

3. Public Borrowing:

Public borrowing is another method of controlling inflation. Through public borrow­ing, the government takes away from public excess purchasing power. This will reduce aggregate demand and hence the price level.

Ordinarily public borrowing is voluntary, left to the free will of individuals. But voluntary public borrowing may not bring to the government sufficient funds to effectively control the inflationary pressures.

In such conditions, compulsory public borrowing is necessary. Through compulsory public borrow­ing a certain percentage of wages or salaries is deducted in exchange for saving bonds which become redeemable after a few years.

In this way, purchasing power can be curtailed for a definite period to curb inflation. Compulsory public borrowing has certain limitations,

(a) It involves the element of compulsion on the public,

(b) It results in frustration if the government borrows from the poorer sections of the public, who cannot contribute to this scheme,

(c) The government should avoid paying back die past loans during inflationary period, otherwise it will generate further inflation.

4. Control of Deficit Financing:

Deficit financing means financing the deficit budget (i.e. excess of government expenditure over its revenue) through printing of new currency. In order to control inflation, the government should minimise deficit financing.

The important thing is that, as far as possible, the deficit should be financed through saving or taxation. The government can sell bonds to non-bank investors, like insurance companies, saving banks etc., which will take away the spending power from the public and thus curb inflation.

300+ TOP Single Phase Induction Motors MCQs & Answers

SINGLE PHASE INDUCTION MOTORS Multiple Choice Questions :-

1. In a split phase motor, the running winding should have

A. high resistance and low inductance
B. low resistance and high inductance
C. high resistance as well as high inductance
D. low resistance as well as low inductiance

Answer: B

2. If the capacitor of a single-phase motor is short-circuited

A. the motor will not start
B. the motor will run
C. the motor will run in reverse direction
D. the motor will run in the same direction at reduced r.p.m.

Answer: A

3. In capacitor start single-phase motors

A. current in the starting winding leads the voltage
B. current in the starting winding lags the voltage
C. current in the starting winding is in phase with voltage in running winding
D. none of the above

Answer: A

4. In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to

A. improve power factor
B. increase overload capacity
C. reduce fluctuations in torque
D. to improve torque

Answer: A

5. In a capacitor start motor, the phase displacement between starting and running winding can be nearly

A. 10°
B. 30°
C. 60°
D. 90°

Answer: D

6. In a split phase motor

A. the starting winding is connected through a centrifugal switch
B. the running winding is connected through a centrifugal switch
C. both starting and running windings are connected through a centrifugal switch
D. centrifugal switch is used to control supply voltage

Answer: A

7. The rotor developed by a single-phase motor at starting is

A. more than i.he rated torque
B. rated torque
C. less than the rated torque
D. zero

Answer: D

8. Which of the following motor will give relatively high starting torque ?

A. Capacitor start motor
B. Capacitor run motor
C. Split phase motor
D. Shaded pole motor

Answer: A

9. Which of the following motor will have relatively higher power factor ?

A. Capacitor run motor
B. Shaded pole motor
C. Capacitor start motor
D. Split phase motor

Answer: A

10. In a shaded pole motor, the shading coil usually consist of

A. a single turn of heavy wire which is in parallel with running winding
B. a single turn of heavy copper wire which is short-circuited and carries only induced current
C. a multilayer fine gauge copper wire in parallel with running winding
D. none of the above

Answer: B

11. In a shaded pole single-phase motor, the revolving field is produced by the use of

A. inductor
B. capacitor
C. resistor
D. shading coils

Answer: D

12. A centrifugal switch is used to dis- connect ‘starting winding when motor has

A. run for about 1 minute
B. run for about 5 minutes
C. picked up about 50 to 70 per cent of rated speed
D. picked up about 10 to 25 per cent of rated speed

Answer: C

13. If a particular application needs high speed and high starting torque, then which of the following motor will be preferred ?

A. Universal motor
B. Shaded pole type motor
C. Capacitor start motor
D. Capacitor start and run motor

Answer: A

14. The value of starting capacitor of a fractional horse power motor will be

A. 100 uF
(6) 200 uF
C. 300 uF
D. 400 uF

Answer: C

15. In repulsion motor direction of rotation of motor

A. is opposite to that of brush shift
B. is the same as that of brush shift
C. is independent of brush shift

Answer: B

16. In a single phase motor the centrifugal switch

A. disconnects auxiliary winding of the motor
B. disconnects main winding of the motor
C. reconnects the main winding the motor
D. reconnects the auxiliary winding of the motor

Answer: A

17. The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be

A. at the end connections
B. at the end terminals
C. anywhere on the winding inside a slot
D. at the slot edge where coil enters or comes out of the slot

Answer: D

18. A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will

A. start and then stop
B. start and run slowly
C. start and run at rated speed
D. not start at all

Answer: D

19. Which of the following motors is used in mixies ?

A. Repulsion motor
B. Reluctance motor
C. Hysteresis motor
D. Universal motor

Answer: D

20. Which of the following motors is inherently self starting ?

A. Split motor
B. Shaded-pole motor
C. Reluctance motor
D. None of these

Answer: B

21. The direction of rotation of an hysteresis motor is determined by

A. interchanging the supply leads
B. position of shaded pole with respect to main pole
C. retentivity of the rotor material
D. none of these

Answer: B

22. Burning out of winding is due to

A. short circuited capacitor
B. capacitor value hiving changed
C. open circuiting of capacitor
D. none of the above

Answer: A

23. Direction of rotation of a split phase motor can be reversed by reversing the connection of

A. running winding only
B. starting winding only
C. either
A. or (b)
D. both
A. and (b)

Answer: C

24. Short-circuiter is used in

A. repulsion induction motor
B. repulsion motor
C. repulsion start induction run motor
D. none of the above

Answer: C

25. The range of efficiency for shaded pole motors is

A. 95% to 99%
B. 80% to 90%
C. 50% to 75%
D. 5% to 35%

Answer: D

26. In a capacitor start single-phase motor, when capacitor is replaced by a resistance

A. torque will increase
B. the motor will consume less power
C. motor will run in reverse direction
D. motor will continue to run in same direction

Answer: D

27. The power factor of a single-phase induction motor is usually

A. lagging
B. always leading
C. unity
D. unity to 0.8 leading

Answer: A

28. A shaded pole motor can be used for

A. toys
B. hair dryers
C. circulators
D. any of the above

Answer: D

29. A hysteresis motor works on the principle of

A. hysteresis loss
B. magnetisation of rotor
C. eddy current loss
D. electromagnetic induction

Answer: A

30. Which of the following motor will give the highest starting torque ?

A. D.C. shunt motor
B. Schrage motor
C. Repulsion start and induction run motor
D. Universal motor

Answer: B

31. For which of the applications a reluctance motor is preferred ?

A. Electric shavers
B. Refrigerators
C. Signalling and timing devices
D. Lifts and hoists

Answer: C

32. The motor used on small lathes is usually

A. universal motor
B. D.C. shunt motor
C. single-phase capacitor run motor
D. 3-phase synchronous motor

Answer: C

33. Which of the following motors is preferred for tape-recorders ?

A. Shaded pole motor
B. Hysteresis motor
C. Two value capacitor motor
D. Universal motor

Answer: B

34. A single-phase induction motor is

A. inherently self-starting with high torque
B. inherently self-starting with low torque
C. inherently non-self-starting with low torque
D. inherently non-self-starting with high torque

Answer: C

35. A schrage motor can run on

A. zero slip
B. negative slip
C. positive slip
D. all of the above

Answer: D

36. A universal motor can run on

A. A.C. only
B. D.C. only
C. either A.C. or D.C.
D. none of the above

Answer: C

37. Which of the following single-phase motors is suitable for timing and control purposes ?

A. Reluctance motor
B. Series motor
C. Repulsion motor
D. Universal motor

Answer: A

38. Single phase induction motor usually operates on

A. 0.6 power factor lagging
B. 0.8 power factor lagging
C. 0.8 power factor leading
D. unity power factor

Answer: A

39. In split-phase motor auxiliary winding is of

A. thick wire placed at the bottom of the slots
B. thick wire placed at the top of the slots
C. thin wire placed at the top of the slots
D. thin wire placed at the bottom of the slots

Answer: C

40. Which of the following motors will operate at high power factor ?

A. Shaped pole motor
B. Split phase motor
C. Capacitor start motor
D. Capacitor run motor

Answer: D

41. In a two value capacitor motor, the capacitor used for running purposes is

A. air capacitor
B. paper spaced oil filled type
C. ceramic type
D. a.c. electrolytic type

Answer: B

42. Which of the following motors can be run on AC. as well as D.C. supply ?

A. Universal motor
B. Repulsion motor
C. Synchronous motor
D. Reluctance motor

Answer: A

43. In A.C. series motor compensating winding is employed to

A. reduce the effects of armature reaction
B. increase the torque
C. reduce sparking at the brushes
D. none of the above

Answer: C

44. Which of the following single-phase induction motors is generally used in time phonographs ?

A. Resistance start
B. Capacitor start capacitor run
C. Shaded pole
D. Universal

Answer: C

45. Which of the following motors has highest starting torque ?

A. Repulsion motor
B. Shaped pole motor
C. Capacitor-start motor
D. Split-phase motor

Answer: C

46. The repulsion-start induction-run motor is used because of

A. good power factor
B. high efficiency
C. minimum cost
D. high starting torque

Answer: D

47. In case of a shaded pole motor the direction of rotation of the motor is

A. from main pole to shaded pole
B. from shaded pole to main pole
C. either of the above depending on voltage
D. either of the above depending on power factor

Answer: A

48. In case of high speed universal motor which of the following needs more attention ?

A. End play
B. Air gap
C. Insulation in rotor
D. Balancing of rotor

Answer: D

49. The wattage rating for a ceiling fan motor will be in the range

A. 200 to 250 W
B. 250 to 500 W
C. 50 to 150 W
D. 10 to 20 W

Answer: C

50. The wattage of motor for driving domestic sewing machine will be around

A. 100 to 150 W
B. 40 to 75 W
C. 10 to 30 W
D. 5 to 10 W

Answer: A

51. Which of the following single-phase motors has relatively poor starting torque ?

A. Universal motor
B. Repulsion motor
C. Capacitor motor
D. All single phase motors have zero starting torque

Answer: C

52. Which type of load is offered by cranes and hoists ?

A. Gradually varying load
B. Non-reversing, no-load start
C. Reversing, light start
D. Reversing, heavy start

Answer: D

53. The speed of a universal motor is generally reduced by using

A. gear trains
B. V-belts
C. brakes
D. chains

Answer: A

54. Which of the following motors can be used for unity power factor ?

A. Capacitor run motor
B. Shaded pole motor
C. Hysteresis motor
D. Schrage motor

Answer: D

55. When a D.C. series motor is connected to A.C. supply, the power factor will be low because of

A. high inductance of field and armature circuits
B. induced current in rotor due to variations of flux
C. fine copper wire winding
D. none of the above

Answer: A

56. The direction of rotation of universal motor can be reversed the by reversing the flow of current through

A. armature winding
B. field winding
C. either armature winding or field winding
D. none of the above

Answer: C

57. In which single-phase motor, the rotor has no teeth or winding ?

A. Split phase motor
B. Reluctance motor
C. Hysteresis motor
D. Universal motor

Answer: C

58. Which motor is normally free from mechanical and magnetic vibrations ?

A. Split phase motor
B. Universal motor
C. Hysteresis motor
D. Shaded pole motor

Answer: C

59. As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for

A. fans
B. blowers
C. sound equipment
D. mixer grinders

Answer: C

60. A reluctance motor

A. is self-starting
B. is constant speed motor
C. needs no D.C. excitation
D. all of the above

Answer: D

61. In a hysteresis motor, the rotor must have

A. retentivity
B. resistivity
C. susceptibility
D. none of the above

Answer: A

62. The rotor of a hysteresis motor is made of

A. aluminium
B. cast iron
C. chrome steel
D. copper

Answer: C

63. The electric motor used in portable drills is

A. capacitor run motor
B. hysteresis motor
C. universal motor
D. repulsion motor

Answer: C

64. Which of the following applications always have some load whenever switched on ?

A. Vacuum cleaners
B. Fan motors
C. Pistol drills
D. All of the above

Answer: C

65. The speed control of universal motor used for sewing machines is by

A. friction
B. varying the resistance
C. tapping the field
D. centrifugal mechanism

Answer: B

66. Torque developed by a single phase induction motor at starting is

A. pulsating
B. uniform
C. none of the above
D. nil

Answer: D

67. In split phase motor main winding is of

A. thin wire placed at the top of the slots
B. thin wire placed at the bottom of the slots
C. thick wire placed at the bottom of the slots
D. thick wire placed at the top of the” slots

Answer: C

68. In repulsion motor, maximum torque is developed when

A. brush axis is at 45° electrical to the field axis
B. brush axis coincides with the field axis
C. brush axis is at 90° electrical to the field axis
D. none of the above

Answer: A

69. If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in

A. damage to the starting winding
B. damage to the centrifugal switch
C. overloading of running winding
D. none of the above

Answer: A

70. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C.

A. shunt motor
B. series motor
C. compound motor
D. separately excited motor

Answer: C

71. In a ceilingfan employing capacitor run motor

A. secondary winding surrounds the primary winding
B. primary winding surrounds the secondary winding
C. both are usual arrangements
D. none of the above

Answer: A

72. The shaded pole motor is used for

A. high starting torque
B. low starting torque
C. medium starting torque
D. very high starting torque

Answer: B

73. The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it

A. improves the efficiency
B. helps the rotor teeth to remain under the stator teeth
C. helps in reducing the tendency of the rotor teeth to remain under the stator teeth
D. improves the power factor

Answer: C

74. The speed/load characteristics of a universal motor is same as that of

A. A.C. motor
B. D.C. shunt motor
C. D.C. series motor
D. none of the above

Answer: C

75. The purpose of stator winding in the compensated repulsion motor is to

A. provide mechanical balance
B. improve power factor and provide better speed regulation
C. prevent hunting in the motor
D. eliminate armature reaction

Answer: B

76. Which of the following motors is used for unity power factor ?

A. Hysteresis motor
B. Schrage motor
C. Universal motor
D. Reluctance motor

Answer: B

77. The motor used for the compressors is

A. d.c. series motor
B. shaded pole motor
C. capacitor-start capacitor-run motor
D. reluctance motor

Answer: C

78. Which of the following motors is used in a situation where load increases with speed ?

A. Induction motor
B. Three-phase series motor
C. Schrage motor
D. Hysteresis motor

Answer: B

79. In repulsion motor, zero torque is developed when

A. brush axis is 45° electrical to field axis
B. brush axis coincides with the field axis
C. brush axis is 90° electrical to field axis
D. both B. and (c)

Answer: D

80. Centrifugal switch disconnects the auxiliary winding of the motor at about ____ percent of synchronous speed

A. 30 to 40
B. 70 to 80
C. 80 to 90
D. 100

Answer: B

81. Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a

A. magnetic relay
B. thermal relay
C. centrifugal switch
D. none of the above

Answer: A

82. If a single phase induction motor runs slower than normal, the most likely defect is

A. worn bearings
B. short-circuit in the winding
C. open-circuit in the winding
D. none of the above

Answer: A

83. Which of the following motors is used in tape-recorders ?

A. Hysteresis motor
B. Reluctance motor
C. Capacitor-run motor
D. Universal motor

Answer: A

84. Which of the following statements regarding two value capacitor motor is incorrect ?

A. It is a reversing motor
B. It is preferred to permanent-split single-value capacitor motor where frequent reversals are required
C. It has low starting as well as rushing currents
D. It has high starting torque

Answer: B

85. Two-value capacitor motor finds increased application as compressor motor in small home air-conditioners
because

A. it is comparatively cheaper
B. it has almost non-destructible capacitor
C. it has low starting as well as running currents at relatively high power factor
D. it is quiet in operation

Answer: C

86. If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then

A. motor will not come up to speed
B. motor will not carry the load
C. current drawn by the motor will be excessively high
D. electrolytic capacitor will, in all probability, suffer break down

Answer: D

87. In a universal motor, the most common cause of brush sparking is

A. open armature winding
B. shorted armature winding
C. shorted field winding”
D. high commutator mica
(e) all of the above
Ans: e

88. If starting winding of a single-phase induction motor is left in the circuit, it will

A. run faster
B. spark at light loads
C. draw excessive current and overheat
D. run slower

Answer: C

89. Most of the fractional horsepower motors have either

A. hard and annealed bearings
B. ball or roller bearings
C. soft and porous bearings
D. plain or sleeve bearings

Answer: D

90. Which of the following statements regarding reluctance-start motor is incorrect ?

A. It is similar to reluctance motor
B. It is basically an induction motor and not a synchronous one
C. So far as its basic working principle is concerned, it is similar to shaded pole motor
D. the air-gap between rotor and salient poles is non- uniform

Answer: A

91. To reverse the direction of rotation of acapacitor start motor while it is running we should

A. disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding
B. disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding
C. reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply
D. reverse the direction of connections of the auxiliary winding and immediately connect it to supply

Answer: A

92. In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will

A. become unstable
B. draw excessive armature current and may burn out
C. fall out of synchronism and come to stand still
D. run as induction motor

Answer: D

93. Which of the following motors has two separate windings on the motor ?

A. Repulsion motor
B. Repulsion induction motor
C. Repulsion start induction run motor
D. None of the above

Answer: B

94. A shaded pole motor does not possess

A. centrifugal switch
B. capacitor
C. commutator
D. all of the above

Answer: D

95. In a A.C. series motor armature coils are usually connected to commutator

A. through resistance
B. through reactances
C. through capacitors
D. solidly

Answer: A

96. Which of the following statements regarding a reluctance motor is incorrect ?

A. It cannot be reversed, ordinarily
B. It requires no D.C. field excitation for its operation
C. It is nothing else but a single-phase, salient pole synchronous-induction motor
D. Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path between stator and rotor

Answer: A

97. A universal motor is one which

A. can be operated either on D.C. or A.C. supply at approximately the same speed and output
B. can be marketed internationally
C. runs at dangerously high speed on no-load

Answer: A

98. A repulsion motor is equipped with

A. slip rings
B. commutator
C. both
A. and (b)
D. none of the above

Answer: B

99. The capacitors used in single-phase capacitor motors have no

A. voltage rating
B. dielectric medium
C. polarity marking
D. definite value

Answer: C

100. If a D.C. series motor is operated on A.C. supply, it will

A. spark excessively
B. have poor efficiency
C. have poor power factor
D. all of the above

Answer: D

101. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on

A. running winding
B. rotor winding
C. field winding
D. compensating winding

Answer: A

102. Which of the following statements regarding repulsion-start induction motor is incorrect ?

A. It requires more maintenance of commutator and other mechanical devices
B. It makes quite a bit of noise on starting
C. In fractional horse power motors, it has replaced the capacitor motors
D. It is not easily reversed

Answer: C

103. A.C. series motor as compared to D.C. series motor has

A. smaller brush width
B. less number of field turns
C. more number of armature turns
D. less air gap
(e) all of the above
Ans: e

104. Locked rotor current of a shaded pole motor is

A. equal to full load current
B. less than full load current
C. slightly more than full load current
D. several times the full load current

Answer: C

105. Speed control of a universal motor is achieved by

A. varying field flux with tapped field windings
B. connecting rheostat in series
C. applying variable voltage by means of silicon controlled rectifier
D. applying variable voltage by means of variable auto-transformer
(e) all of the above methods
Ans: e

116. Hysteresis motor is particularly useful for high-quality record players and tape-recorders because

A. it revolves synchronously
B. it is not subject to any magnetic or mechanical vibrations
C. it can be easily manufactured in extremely small sizes of up to 1 W output
D. it develops hysteresis torque which is extremely steady both in amplitude and phase

Answer: D

117. Which of the following statements regarding hysteresis motor is in incorrect ?

A. It is extremely sensitive to fluctuations in supply voltage
B. Its high starting torque is due to its high rotor hysteresis loss
C. It is extremely quiet in operation
D. It accelerates from rest to full-speed almost instantaneously

Answer: A

118. Which of the following statements regarding single-phase induction motoris correct ?

A. It requires only one winding
B. It can rotate in one direction only
C. It is self-starting
D. It is not self-starting

Answer: D

119. The starting winding of a single-phase motor is placed in

A. armature
B. field
C. rotor
D. stator

Answer: D

120. The speed of a universal motor is usually reduced by using

A. gearing
B. belts
C. brakes
D. chains

Answer: A

[PDF Notes] Here is your short essay on Inflation and Reflation

Inflation is different from reflation in exactly the same manner as deflation is different from disinflation. Inflation is a situation of rising prices after the full-employment level is reached.

In other words, it is a phenomenon of rising prices without any increase in output and employment. Reflation, on the other hand, is a situation of moderately rising prices when attempts are made to pull the system out of depths of depression.

In the words of G.D. H. Cole, “Reflation may be defined as inflation deliberately undertaken to relieve a depression.”

Inflation and reflation resemble each other in two respects:

(a) In both, money supply increases,

(b) Both lead to a rise in the price level. But still there are some basic differences between inflation and reflation:

(a) Inflation causes a serious problem of rising prices without any increase in output and employment. Reflation does not create such problem. It rather saves the already shattered economy from the problem of deflation.

(b) Inflation may be due to natural factors or may be the result of deliberate policy of the government. But, reflation is always adopted by the government as a deliberate policy,

(c) Inflation occurs after the level of full employment, whereas, reflation occurs before the level of full employment.

(d) Prices rise very rapidly under inflation, while they rise very slowly under reflation.

300+ TOP Polyphase Induction Motors MCQs and Answers

Polyphase Induction Motors Multiple Choice Questions

1. Which of the following component is usually fabricated out of silicon steel ?
(a) Bearings
(b) Shaft
(c) Statorcore
(d) None of the above
Answer: c

2. The frame of an induction motor is usually made of
(a) silicon steel
(b) cast iron
(c) aluminium
(d) bronze
Answer: b

3. The shaft of an induction motor is made of
(a) stiff
(b) flexible
(c) hollow
(d) any of the above
Answer: a

4. The shaft of an induction motor is made of
(a) high speed steel
(b) stainless steel
(c) carbon steel
(d) cast iron
Answer: c

5. In an induction motor, no-load the slip is generally
(a) less than 1%
(b) 1.5%
(c) 2%
(d) 4%
Answer: a

6. In medium sized induction motors, the slip is generally around
(a) 0.04%
(b) 0.4%
(c) 4%
(d) 14%
Answer: c

7. In squirrel cage induction motors, the rotor slots are usually given slight skew in order to
(a) reduce windage losses
(b) reduce eddy currents
(c) reduce accumulation of dirt and dust
(d) reduce magnetic hum
Answer: d

8. In case the air gap in an induction motor is increased
(a) the magnetising current of the rotor will decrease
(b) the power factor will decrease
(c) speed of motor will increase
(d) the windage losses will increase
Answer: b

9. Slip rings are usually made of
(a) copper
(b) carbon
(c) phospor bronze
(d) aluminium
Answer: c

10. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be
(a) 200 Hz
(b) 50 Hz
(c) 2 Hz
(d) 0.2 Hz
Answer: c

11. In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be
(a) Ns
(b) s.N,
(c) (l-s)Ns
(d) (Ns-l)s
Answer: c

12. The efficiency of an induction motor can be expected to be nearly
(a) 60 to 90%
(b) 80 to 90%
(c) 95 to 98%
(d) 99%
Answer: b

13. The number of slip rings on a squirrel cage induction motor is usually
(a) two
(b) three
(c) four
(d) none
Answer: d

14. The starting torque of a squirrel-cage induction motor is
(a) low
(b) negligible
(c) same as full-load torque
(d) slightly more than full-load torque
Answer: a

15. A double squirrel-cage induction motor has
(a) two rotors moving in oppsite direction
(b) two parallel windings in stator
(c) two parallel windings in rotor
(d) two series windings in stator
Answer: c

16. Star-delta starting of motors is not possible in case of
(a) single phase motors
(b) variable speed motors
(c) low horse power motors
(d) high speed motors
Answer: a

17. The term ‘cogging’ is associated with
(a) three phase transformers
(b) compound generators
(c) D.C. series motors
(d) induction motors
Answer: d

18. In case of the induction motors the torque is
(a) inversely proportional to (Vslip)
(b) directly proportional to (slip)2
(c) inversely proportional to slip
(d) directly proportional to slip
Answer: d

19. An induction motor with 1000 r.p.m. speed will have
(a) 8 poles
(b) 6 poles
(c) 4 poles
(d) 2 poles
Answer: b

20. The good power factor of an induction motor can be achieved if the average flux density in the air gap is
(a) absent
(b) small
(c) large
(d) infinity
Answer: b

21. An induction motor is identical to
(a) D.C. compound motor
(b) D.C. series motor
(c) synchronous motor
(d) asynchronous motor
Answer: d

22. The injected e.m.f. in the rotor of induction motor must have
(a) zero frequency
(b) the same frequency as the slip frequency
(c) the same phase as the rotor e.m.f.
(d) high value for the satisfactory speed control
Answer: b

23. Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor ?
(a) By changing the number of stater poles
(b) Rotor rheostat control
(c) By operating two motors in cascade
(d) By injecting e.m.f. in the rotor circuit
Answer: a

24. The crawling in the induction motor is caused by
(a) low voltage supply
(b) high loads
(c) harmonics developed in the motor
(d) improper design of the machine
(e) none of the above
Answer: c

25. The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type
(a) star connected only
(b) delta connected only
(c) (a) and (b) both
(d) none of the above
Answer: c

26. The torque developed in the cage induction motor with auto starter is
(a) k/torque with direct switching
(6) K x torque with direct switching
(c) K2 x torque with direct switching
(d) k2/torque with direct switching
Answer: c

27. When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered
(a) in series
(b) in parallel
(c) in series-parallel
(d) in parallel with stater
Answer: b

28. It is advisable to avoid line-starting of induction motor and use starter because
(a) motor takes five to seven times its full load current
(b) it will pick-up very high speed and may go out of step
(c) it will run in reverse direction
(d) starting torque is very high
Answer: a

29. Stepless speed control of induction motor is possible by which of the following methods ?
(a) e.m.f. injection in rotor eueuit
(b) Changing the number of poles
(c) Cascade operation
(d) None of the above
Answer: b

30. Rotor rheostat control method of speed control is used for
(a) squirrel-cage induction motors only
(b) slip ring induction motors only
(c) both (a) and (b)
(d) none of the above
Answer: b

31. In the circle diagram for induction motor, the diameter of the circle represents
(a) slip
(b) rotor current
(c) running torque
(d) line voltage
Answer: b

32. For which motor the speed can be controlled from rotor side ?
(a) Squirrel-cage induction motor
(b) Slip-ring induction motor
(c) Both (a) and (b)
(d) None of the above
Answer: b

33. If any two phases for an induction motor are interchanged
(a) the motor will run in reverse direction
(b) the motor will run at reduced speed
(c) the motor will not run
(d) the motor will burn
Answer: a

34. An induction motor is
(a) self-starting with zero torque
(b) self-starting with high torque
(c) self-starting with low torque
(d) non-self starting
Answer: c

35. The maximum torque in an induction motor depends on
(a) frequency
(b) rotor inductive reactance
(c) square of supply voltage
(d) all of the above
Answer: d

36. In three-phase squirrel-cage induction motors
(a) rotor conductor ends are short-circuited through slip rings
(b) rotor conductors are short-circuited through end rings
(c) rotor conductors are kept open
(d) rotor conductors are connected to insulation
Answer: b

37. In a three-phase induction motor, the number of poles in the rotor winding is always
(a) zero
(b) more than the number of poles in stator
(c) less than number of poles in stator
(d) equal to number of poles in stator
Answer: d

38. DOL starting of induction motors is usually restricted to
(a) low horsepower motors
(b) variable speed motors
(c) high horsepower motors
(d) high speed motors
Answer: a

39. The speed of a squirrel-cage induction motor can be controlled by all of the following except
(a) changing supply frequency
(b) changing number of poles
(c) changing winding resistance
(d) reducing supply voltage
Answer: c

40. The ‘crawling” in an induction motor is caused by
(a) high loads
(6) low voltage supply
(c) improper design of machine
(d) harmonics developed in the motor
Answer: d

41. The power factor of an induction motor under no-load conditions will be closer to
(a) 0.2 lagging
(b) 0.2 leading
(c) 0.5 leading
(d) unity
Answer: a

42. The ‘cogging’ of an induction motor can be avoided by
(a) proper ventilation
(b) using DOL starter
(c) auto-transformer starter
(d) having number of rotor slots more or less than the number of stator slots (not equal)
Answer: d

43. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as
(a) humming
(b) hunting
(c) crawling
(d) cogging
Answer: c

44. Slip of an induction motor is negative when
(a) magnetic field and rotor rotate in opposite direction
(b) rotor speed is less than the synchronous speed of the field and are in the same direction
(c) rotor speed is more than the synchronous speed of the field and are in the same direction
(d) none of the above
Answer: c

45. Size of a high speed motor as compared to low speed motor for the same H.P. will be
(a) bigger
(b) smaller
(c) same
(d) any of the above
Answer: b

46. A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor
(a) will continue running burning its one phase
(b) will continue running burning its two phases
(c) will stop and carry heavy current causing permanent damage to its winding
(d) will continue running without any harm to the winding
Answer: a

47. A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the
motor
(a) will continue running burning its one phase
(b) will continue running burning its two phase
(c) will stop and carry heavy current causing permanent damage to its winding
(d) will continue running without any harm to the winding
Answer: c

48. Low voltage at motor terminals is due to
(a) inadequate motor wiring
(b) poorely regulated power supply
(c) any one of the above
(d) none of the above
Answer: c

49. In an induction motor the relationship between stator slots and rotor slots is that
(a) stator slots are equal to rotor slots
(b) stator slots are exact multiple of rotor slots
(c) stator slots are not exact multiple of rotor slots
(d) none of the above
Answer: c

50. Slip ring motor is recommended where
(a) speed control is required
(6) frequent starting, stopping and reversing is required
(c) high starting torque is needed
(d) all above features are required
Answer: d

51. As load on an induction motor goes on increasing
(a) its power factor goes on decreasing
(b) its power factor remains constant
(c) its power factor goes on increasing even after full load
(d) its power factor goes on increasing up to full load and then it falls again
Answer: d

52. If a 3-phase supply is given to the stator and rotor is short circuited rotor will move
(a) in the opposite direction as the direction of the rotating field
(b) in the same direction as the direction of the field
(c) in any direction depending upon phase squence of supply
Answer: b

53. It is advisable to avoid line starting of induction motor and use starter because
(a) it will run in reverse direction
(b) it will pick up very high speed and may go out of step
(c) motor takes five to seven times its full load current
(d) starting torque is very high
Answer: c

54. The speed characteristics of an induction motor closely resemble the speedload characteristics of which of the
following machines
(a) D.C. series motor
(b) D.C. shunt motor
(c) universal motor
(d) none of the above
Answer: b

55. Which type of bearing is provided in small induction motors to support the rotor shaft ?
(a) Ball bearings
(b) Cast iron bearings
(c) Bush bearings
(d) None of the above
Answer: a

56. A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will
eventually happen ? It will
(a) stall after sometime
(b) stall immediately
(c) continue to run at lower speed without damage
(d) get heated and subsequently get damaged
Answer: d

57. 5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the
costliest ?
(a) 730 r.p.m.
(b) 960 r.p.m.
(c) 1440 r.p.m.
(d) 2880 r.p.m.
Answer: a

58. A 3-phase slip ring motor has
(a) double cage rotor
(6) wound rotor
(c) short-circuited rotor
(d) any of the above
Answer: b

59. The starting torque of a 3-phase squirrel cage induction motor is
(a) twice the full load torque
(b) 1.5 times the full load torque
(c) equal to full load torque
Answer: b

60. Short-circuit test on an induction motor cannot be used to determine
(a) windage losses
(b) copper losses
(c) transformation ratio
(d) power scale of circle diagram
Answer: a

61. In a three-phase induction motor
(a) iron losses in stator will be negligible as compared to that in rotor
(6) iron losses in motor will be neg¬ligible as compared to that in rotor
(c) iron losses in stator will be less than that in rotor
(d) iron losses in stator will be more than that in rotor
Answer: d

62. In case of 3-phase induction motors, plugging means
(a) pulling the motor directly on line without a starter
(b) locking of rotor due to harmonics
(c) starting the motor on load which is more than the rated load
(d) interchanging two supply phases for quick stopping
Answer: d

63. Which is of the following data is required to draw the circle diagram for an induction motor ?
(a) Block rotor test only
(b) No load test only
(c) Block rotor test and no-load test
(d) Block rotor test, no-load test and stator resistance test
Answer: d

64. In three-phase induction motors sometimes copper bars are placed deep in the rotor to
(a) improve starting torque
(b) reduce copper losses
(c) improve efficiency
(d) improve power factor
Answer: a

65. In a three-phase induction motor
(a) power factor at starting is high as compared to that while running
(b) power factor at starting is low as compared to that while running
(c) power factor at starting in the same as that while running
Answer: b

66. The vafcie of transformation ratio of an induction motor can be found by
(a) open-circuit test only
(b) short-circuit test only
(c) stator resistance test
(d) none of the above
Answer: b

67. The power scale of circle diagram of an induction motor can be found from
(a) stator resistance test
(6) no-load test only
(c) short-circuit test only
(d) noue of the above
Answer: c

68. The shape of the torque/slip curve of induction motor is
(a) parabola
(b) hyperbola
(c) rectangular parabola
(d) straigth line
Answer: c

69. A change of 4% of supply voltage to an induction motor will produce a change of appromimately
(a) 4% in the rotor torque
(b) 8% in the rotor torque
(c) 12% in the rotor torque
(d) 16% in the rotor torque
Answer: d

70. The stating torque of the slip ring induction motor can be increased by adding
(a) external inductance to the rotor
(b) external resistance to the rotor
(c) external capacitance to the rotor
(d) both resistance and inductance to rotor
Answer: b

71. A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be
(a) 0.01
(b) 0.02
(c) 0.03
(d) 0.04
Answer: d

72. The complete circle diagram of induetion motor can be drawn with the help of data found from
(a) noload test
(6) blocked rotor test
(c) stator resistance test
(d) all of the above
Answer: d

73. In the squirrel-cage induction motor the rotor slots are usually given slight skew
(a) to reduce the magnetic hum and locking tendency of the rotor
(b) to increase the tensile strength of the rotor bars
(c) to ensure easy fabrication
(d) none of the above
Answer: a

74. The torque of a rotor in an induction motor under running condition is maximum
(a) at the unit value of slip
(b) at the zero value of slip
(c) at the value of the slip which makes rotor reactance per phase equal to the resistance per phase
(d) at the value of the slip which makes the rotor reactance half of the rotor
Answer: c

75. What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero ?
(a) The slip of the motor will be 5%
(b) The rotor will not run
(c) The rotor will run at very high speed
(d) The torque produced will be very large
Answer: b

76. The circle diagram for an induction motor cannot be used to determine
(a) efficiency
(b) power factor
(c) frequency
(d) output
Answer: a

77. Blocked rotor test on induction motors is used to find out
(a) leakage reactance
(b) power factor on short circuit
(c) short-circuit current under rated voltage
(d) all of the above
Answer: d

78. Lubricant used for ball bearing is usually
(a) graphite
(b) grease
(c) mineral oil
(d) molasses
Answer: b

79. An induction motor can run at synchronous speed when
(a) it is run on load
(b) it is run in reverse direction
(c) it is run on voltage higher than the rated voltage
(d) e.m.f. is injected in the rotor circuit
Answer: d

80. Which motor is preferred for use in mines where explosive gases exist ?
(a) Air motor
(b) Induction motor
(c) D.C. shunt motor
(d) Synchronous motor
Answer: a

81. The torque developed by a 3-phase induction motor least depends on
(a) rotor current
(b) rotor power factor
(c) rotor e.m.f.
(d) shaft diameter
Answer: d

82. In an induction motor if air-gap is increased
(a) the power factor will be low
(b) windage losses will be more
(c) bearing friction will reduce
(d) copper loss will reduce In an induction motor
Answer: a

83. In induction motor, percentage slip depends on
(a) supply frequency
(b) supply voltage
(c) copper losses in motor
(d) none of the above
Answer: c

84. When /?2 is the rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running conditions will be
(a) sR2X2 = 1
(b) sR2 = X2
(c) R2 = sX2
(d) R2 = s2X2
Answer: c

85. In case of a double cage induction motor, the inner cage has
(a) high inductance arid low resistance
(b) low inductance and high resistance
(c) low inductance and low resistance
(d) high inductance and high resistance
Answer: a

86. The low power factor of induction motor is due to
(a) rotor leakage reactance
(b) stator reactance
(c) the reactive lagging magnetizing current necessary to generate the magnetic flux
(d) all of the above
Answer: d

87. Insertion of reactance in the rotor circuit
(a) reduces starting torque as well as maximum torque
(b) increases starting torque as well as maximum torque
(c) increases starting torque but maxi-mum torque remains unchanged
(d) increases starting torque but maxi-mum torque decreases
Answer: a

88. Insertion of resistance in the rotcir of an induction motor to develop a given torque
(a) decreases the rotor current
(b) increases the rotor current
(c) rotor current becomes zero
(d) rotor current rernains same
Answer: d

89. For driving high inertia loods best type of induction motor suggested is
(a) slip ring type
(b) squirrel cage type
(c) any of the above
(d) none of the above
Answer: a

90. Temperature of the stator winding of a three phase induction motor is obtained by
(a) resistance rise method
(b) thermometer method
(c) embedded temperature method
(d) all above methods
Answer: d

91. The purpose of using short-circuit gear is
(a) to short circuit the rotor at slip rings
(b) to short circuit the starting resistances in the starter
(c) to short circuit the stator phase of motor to form star
(d) none of the above
Answer: a

92. In a squirrel cage motor the induced e.m.f. is
(a) dependent on the shaft loading
(b) dependent on the number of slots
(c) slip times the stand still e.m.f. induced in the rotor
(d) none of the above
Answer: c

93. Less maintenance troubles are experienced in case of
(a) slip ring induction motor
(6) squirrel cage induction motor
(c) both (a) and (b)
(d) none of the above
Answer: b

94. A squirrel cage induction motor is not selected when
(a) initial cost is the main consideration
(b) maintenance cost is to be kept low
(c) higher starting torque is the main consideration
(d) all above considerations are involved
Answer: c

95. Reduced voltage starter can be used with
(a) slip ring motor only but not with squirrel cage induction motor
(b) squirrel cage induction motor only but not with slip ring motor
(c) squirrel cage as well as slip ring induction motor
(d) none of the above
Answer: c

96. Slip ring motor is preferred over squirrel cage induction motor where
(a) high starting torque is required
(b) load torque is heavy
(c) heavy pull out torque is required
(d) all of the above
Answer: a

97. In a star-delta starter of an induction motor
(a) resistance is inserted in the stator
(b) reduced voltage is applied to the stator
(c) resistance is inserted in the rotor
(d) applied voltage perl stator phase is 57.7% of the line voltage
Answer: d

98. The torque of an induction motor is
(a) directly proportional to slip
(b) inversely proportional to slip
(c) proportional to the square of the slip
(d) none of the above
Answer: a

99. The rotor of an induction motor runs at
(a) synchronous speed
(b) below synchronous speed
(c) above synchronous speed
(d) any of the above
Answer: b

100. The starting torque of a three phase induction motor can be increased by
(a) increasing slip
(b) increasing current
(c) both (a) and (b)
(d) none of the above
Answer: c

110. Insertion of resistance in the stater of an induction motor
(a) increases the load torque
(b) decreases the starting torque
(c) increases the starting torque
(d) none of the above
Answer: b

Polyphase Induction Motors Objective Questions with Answers Pdf Download

300+ [UPDATED] Entomology Interview Questions

  1. 1. Can Mosquitoes Transmit Aids Or Hepatitis?

    No, despite testing by several laboratories, no conclusive evidence has been found to suggest that mosquitoes can transmit these diseases. The virus that causes AIDS can not survive in the mosquito like some other viruses such as Ross River virus. The mouthparts of a mosquito (the proboscis) are not like a syringe, i.e with a single channel where blood can go up and down. Rather, the proboscis has separate channels for saliva flow and blood intake, hence these diseases are not likely to be transmitted in the manner they can be with syringes. 

  2. 2. Does Ross River Only Occur In Northern Australia?

    No, the disease occurs right across Australia in all states, including Tasmania. The locations that have little disease include those areas that are very dry such as the deserts (although disease transmission may occur after heavy rains), much of the mountain range of eastern Australia, and the major southern cities (although there may be cases on the outskirts). 


    3. Agricultural Interview Questions

  3. 3. Can I Get Ross River Disease In Sydney?

    The chances are small. Within Sydney there are none of the animals (such as kangaroos) that act as the major host for the virus. However, there are known mosquito vectors present and with infected people returning from country areas where the virus is present, it is possible that human-mosquito-human transmission (normally the cycle is animal host-mosquito-human) may occur, although this has never been documented. Occasionally outbreaks of Ross River virus occur on the fringes of major cities, where both mosquito vector and animal hosts occur together, and this has happened in Perth, Brisbane, and in Sydney in the summer of 1996-97. 

  4. 4. How Do I Prevent Mosquito Bites?

    Prevention of mosquito bites can be achieved either through undertaking active mosquito control or by the use of personal protective measures. A variety of active mosquito control measures are available, including habitat modification in order to reduce water availability for breeding of the larval stage, through to the use of appropriate insecticides for controlling the larval or adult stage. These are large scale control measures which can only be undertaken by government bodies such as local councils. On a small scale, householders can ensure that their own backyard does not contain water holding containers which can provide suitable mosquito larval habitats (e.g. undrained pot plants, blocked gutters, disused bottles, old tyres, etc). Personal protective measures include: avoiding known mosquito infested areas, especially at dawn and dusk when mosquitoes are most active; ensuring that houses are adequately fly screened; using insect repellents that contain the chemical DEET, and reapplying it regularly; and wearing long sleeved shirts and pants. Other preventative measures include government based programs that undertake mosquito monitoring and virus surveillance from mosquitoes. These programs aim to act as an early warning system for virus activity by monitoring weather patterns, mosquito populations and viruses such as Ross River, Barmah Forest, Murray Valley encephalitis and Kunjin. In New South Wales, such a program has been running for several years at the Department of Medical Entomology at Westmead Hospital. 

  5. 5. How Do I Treat Mosquito Bites To Stop The Itch?

    Cold water and ice can be useful, although ice should not be applied directly to the skin. A variety of commercial preparations can be obtained from the chemist including Eurax and Stingose. In severe cases, oral antihistamines may have to be administered and if symptoms persist, a physician should be consulted. 


    6. Asphalt Concrete Paving Interview Questions

  6. 6. How Many Species Of Mosquitoes Are There?

    In Australia there are around 400 species but only approximately 10 are commonly abundant and represent a serious pest threat because of their nuisance biting or their ability to transmit disease. 

  7. 7. How Long Does A Mosquito Live?

    This varies with the mosquito species and the time of the year. Some species may only live for less than a week, while others can live for several months over the winter months. 


    8. Soil Science Interview Questions

  8. 8. Mosquitoes Are Coming Into The House, How Do I Stop Them?

    Intact flyscreens on all windows and doors will prevent mosquitoes entering. The main species that tend to enter houses are those that breed around houses. Thus it is important that any container that can hold water be emptied or removed. 

  9. 9. Will Global Warming (from The Greenhouse Effect) Result In An Increase In Mosquito-borne Diseases?

    This is very difficult to determine. Currently there are different theories as to the level and amount of climate change. Some models predict large changes in rainfall patterns, while other predict small changes. We may expect with increases in rainfall there would be an increase in mosquito numbers and a subsequent increase in mosquito-borne diseases, however this may not be the case. The biology of mosquito-borne diseases is a very complex issue and involves the mosquito vector, reservoir hosts and even sociological factors. In some areas, an increase in rainfall may even lead to a decrease in mosquito numbers! All we can be certain of, with global warming, is that there will be a change in the amount and distribution of disease, but to what extent, it is not known. 


    10. Batch Plant Interview Questions

  10. 10. Are Mosquitoes From Wetlands A Health Or Pest Risk?

    They can be under certain circumstances, this is described in detail in the Fact Sheets on “Mosquito Production and Management – Saline Wetlands, Freshwater and Constructed Wetlands, and Irrigation Wetlands”.

  11. 11. Is There Lyme Disease In Australia?

    There is some debate as to the presence of Lyme disease in Australia. Some workers believe that it is here. However, the most comprehensive tick survey undertaken in Australia to date, found no conclusive evidence for any spirochaete bacteria that may be responsible for the disease (see fact sheet on Lyme Disease for more information). If Lyme Disease is present in Australia, then that it must be very rare. 


    12. Zoology Interview Questions

  12. 12. I Left The Head Of The Tick Behind, What Should I Do Now?

    When a tick is removed, commonly a portion of the head or the mouthparts are left behind. Generally this does not cause any problems as the head of the tick will fall out as the skin sloughs off in time. However, if a local reaction does occur, then a physician should be consulted. 


    13. Agricultural Interview Questions

  13. 13. Is It Ok To Use Kerosene On The Tick To Remove It?

    No, this often causes the tick to inject its saliva into the host and can increase the risk of transmitting disease causing organisms, or increase the risk of death from paralysis. 

  14. 14. How Do I Remove A Tick?

    Insect repellent may be applied to the tick, which will kill it. The tick should be removed with the aid of a pair of fine tipped forceps; the tick needs to be grasped as close the skin of the host as possible, and then forcibly removed. 

  15. 15. How Do I Prevent Tick Bite?

    A variety of methods exist to reduce the possibility of tick bite and prevention is best achieved via some form of personal protection. People who bushwalk in tick infested areas need to use an insect repellent, particularly one containing the chemical DEET, and this should be applied regularly to clothing. Wearing light coloured clothing is useful as ticks can be more easily spotted. Bushland locations which are highly tick infested should be avoided. 


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  16. 16. How Do I Treat Tick Bite?

    Treatment is the same as that for mosquitoes; cold water and ice can be useful to relieve itching, although ice should not be applied directly to the skin. A variety of commercial preparations can be obtained from the chemist including Eurax and Stingose. In severe cases, oral antihistamines may have to be administered and if symptoms persist, a physician should be consulted. 

  17. 17. I Have Ticks In The Backyard, How Can I Get Rid Of Them?

    This is very difficult, if not impossible to achieve. As ticks are very susceptible to desiccation, removing trees and shrubs will increase the amount of light to the ground, thereby decreasing the humidity levels and making conditions unfavourable for tick survival. Often this involves considerable environmental destruction and is not advisable. The presence of ticks in an area indicates that there are native animal hosts present (usually bandicoots) and this suggests that the environment is natural and healthy. If ticks are present, then it is best to undertake tick avoidance measures.

  18. 18. I Had A Severe Reaction After Removing A Tick, What Can I Do?

    If an individual reacts severely to a tick bite, then potentially a life threatening anaphylactic reaction may occur in the future and tick avoidance measures must be a priority. Until recently it was possible for such people to be desensitised, however this is no longer possible do to the non-availability of reagents. 


    19. Asphalt Concrete Paving Interview Questions

  19. 19. Do Ticks Jump?

    No. People often think that because a tick often attaches in the head, that the tick has jumped out of the trees. As ticks are susceptible to desiccation, they tend not to climb very high in the vegetation. Once on a host, the tick may take several hours before finding a site to attach to, which is often on the head. Ticks do not have legs that are adapted for jumping. 

  20. 20. How Long Does A Tick Have To Be Attached Before Paralysis Occurs?

    This varies with individuals and some may not even experience paralysis with a fully engorged tick. Generally symptoms of paralysis start showing 2-4 days after the tick has attached.

  21. 21. What Is Scabies?

    Scabies is a condition caused by the mite Sarcoptes scabiei, which burrows under the sensitive sections of skin, causing severe irritation. Transmission is usually from one infected individual to another. Diagnosis can only be achieved with a skin scraping, which is examined by microscopy, Scabies is easily treated with various readily obtained preparations from chemists.

  22. 22. Do Dogs Carry Human Scabies?

    No, scabies mites are generally host specific and human infections are typically acquired from another infected human. 

  23. 23. Can Bird Mites Burrow Under The Skin?

    No, bird mites do not do this. Bird mites will repeatedly “test bite” but do not feed continuously. 

  24. 24. How Do I Get Rid Of A Bird Mite Infestation?

    Bird mite infestations originate from birds that are nesting within the house. The mites become a problem when the young birds fledge and the mites in the nest search for a new host to feed on. It is thus important that all nesting material is removed, sealed in plastic bags and discarded, and all access points for birds into the roof be sealed to prevent further reinfestations. 


    25. Soil Science Interview Questions

  25. 25. Do Head Lice Only Affect Dirty Children?

    No, all children are equally at risk of acquiring head lice. Transmission occurs very easily through contact from one infected child to another. Being clean does not prevent infection.

  26. 26. Do I Need To Treat All Family Members If One Child Has Head Lice?

    Yes, head lice are very easily transmitted from one family member to another. Not everyone will show signs of an infestation and thus all members should be treated at the same time. Likewise all bed linen should be washed in hot water and left to dry in the sun (or a hot clothes dryer). 

  27. 27. Can I Get Pubic Lice From Dogs, Toilet Seats Or Towels?

    No, pubic lice are host specific and are not a parasite of dogs. Acquiring public lice from toilet seats is unlikely, although sharing towels with an infested person can result in transmission. 


    28. Batch Plant Interview Questions

  28. 28. What Symptoms Result From The Bite Of A White-tailed Spider?

    Generally there is local pain, swelling and itching at the site of the bite. There is some evidence that local skin ulceration can occur although this is appears to be uncommon. 

  29. 29. Something Seems To Be Biting Me And Causing A Severe Itch, What Can It Be?

    This is very difficult to determine as there are many things that can irritate, and individual reactions vary from person to person. Insects may be the problem and there are a large variety that can bite (e.g. fleas, flies, mosquitoes, bird mites, etc) or irritate (various urticating caterpillars). However, humans are typically exposed daily to a huge variety of chemicals and other irritants, and these could be cause of the problem rather than insects or mites. 

  30. 30. What Kinds Of Bugs Can The Entomologist Identify?

    Any insects, spiders, ticks, or mites of medical importance. The health department does not provide identification services for agricultural, urban, or garden pests. Those specimens should be sent to the Cooperative Extension Service.

300+ TOP TRANSFORMERS MCQs and Answers [Latest]

TRANSFORMERS Multiple Choice Questions with Answers

1. Which of the following does not change in a transformer ?
(a) Current
(b) Voltage
(c) Frequency
(d) All of the above
Answer: c

2. In a transformer the energy is conveyed from primary to secondary
(a) through cooling coil
(b) through air
(c) by the flux
(d) none of the above
Answer: c

3. A transformer core is laminated to
(a) reduce hysteresis loss
(b) reduce eddy current losses
(c) reduce copper losses
(d) reduce all above losses
Answer: b

4. The degree of mechanical vibrations produced by the laminations of a transformer depends on
(a) tightness of clamping
(b) gauge of laminations
(c) size of laminations
(d) all of the above
Answer: d

5. The no-load current drawn by transformer is usually what per cent of the full-load current ?
(a) 0.2 to 0.5 per cent
(b) 2 to 5 per cent
(c) 12 to 15 per cent
(d) 20 to 30 per cent
Answer: b

6. The path of a magnetic flux in a transformer should have
(a) high resistance
(b) high reluctance
(c) low resistance
(d) low reluctance
Answer: d

7. No-load on a transformer is carried out to determine
(a) copper loss
(b) magnetising current
(c) magnetising current and loss
(d) efficiency of the transformer
Answer: c

8. The dielectric strength of transformer oil is expected to be
(a) lkV
(b) 33 kV
(c) 100 kV
(d) 330 kV
Answer: b

9. Sumpner’s test is conducted on trans-formers to determine
(a) temperature
(b) stray losses
(c) all-day efficiency
(d) none of the above
Answer: a

10. The permissible flux density in case of cold rolled grain oriented steel is around
(a) 1.7 Wb/m2
(b) 2.7 Wb/m2
(c) 3.7 Wb/m2
(d) 4.7 Wb/m2
Answer: a

11. The efficiency of a transformer will be maximum when
(a) copper losses = hysteresis losses
(b) hysteresis losses = eddy current losses
(c) eddy current losses = copper losses
(d) copper losses = iron losses
Answer: d

12. No-load current in a transformer
(a) lags behind the voltage by about 75°
(b) leads the voltage by about 75°
(c) lags behind the voltage by about 15°
(d) leads the voltage by about 15°
Answer: a

13. The purpose of providing an iron core in a transformer is to
(a) provide support to windings
(b) reduce hysteresis loss
(c) decrease the reluctance of the magnetic path
(d) reduce eddy current losses
Answer: c

14. Which of the following is not a part of transformer installation ?
(a) Conservator
(b) Breather
(c) Buchholz relay
(d) Exciter
Answer: d

15. While conducting short-circuit test on a transformer the following side is short circuited
(a) High voltage side
(b) Low voltage side
(c) Primary side
(d) Secondary side
Answer: b

16. In the transformer following winding has got more cross-sectional area
(a) Low voltage winding
(b) High voltage winding
(c) Primary winding
(d) Secondary winding
Answer: a

17. A transformer transforms
(a) voltage
(b) current
(c) power
(d) frequency
Answer: c

18. A transformer cannot raise or lower the voltage of a D.C. supply because
(a) there is no need to change the D.C. voltage
(b) a D.C. circuit has more losses
(c) Faraday’s laws of electromagnetic induction are not valid since the rate of change of flux is zero
(d) none of the above
Answer: c

19. Primary winding of a transformer
(a) is always a low voltage winding
(b) is always a high voltage winding
(c) could either be a low voltage or high voltage winding
(d) none of the above
Answer: c

20. Which winding in a transformer has more number of turns ?
(a) Low voltage winding
(b) High voltage winding
(c) Primary winding
(d) Secondary winding
Answer: b

21. Efficiency of a power transformer is of the order of
(a) 100 per cent
(b) 98 per cent
(c) 50 per cent
(d) 25 per cent
Answer: b

22. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are
(a) friction and windage losses
(b) copper losses
(c) hysteresis and eddy current losses
(d) none of the above
Answer: c

23. A common method of cooling a power transformer is
(a) natural air cooling
(b) air blast cooling
(c) oil cooling
(d) any of the above
Answer: c

24. The no load current in a transformer lags behind the applied voltage by an angle of about
(a) 180°
(b) 120″
(c) 90°
(d) 75°
Answer: d

25. In a transformer routine efficiency depends upon
(a) supply frequency
(b) load current
(c) power factor of load
(d) both (b) and (c)
Answer: d

26. In the transformer the function of a conservator is to
(a) provide fresh air for cooling the transformer
(b) supply cooling oil to transformer in time of need
(c) protect the transformer from damage when oil expends due to heating
(d) none of the above
Answer: c

27. Natural oil cooling is used for transformers up to a rating of
(a) 3000 kVA
(b) 1000 kVA
(c) 500 kVA
(d) 250 kVA
Answer: a

28. Power transformers are designed to have maximum efficiency at
(a) nearly full load
(b) 70% full load
(c) 50% full load
(d) no load
Answer: a

29. The maximum efficiency of a distribution transformer is
(a) at no load
(b) at 50% full load
(c) at 80% full load
(d) at full load
Answer: b

30. Transformer breaths in when
(a) load on it increases
(b) load on it decreases
(c) load remains constant
(d) none of the above
Answer: b

31. No-load current of a transformer has
(a) has high magnitude and low power factor
(b) has high magnitude and high power factor
(c) has small magnitude and high power factor
(d) has small magnitude and low power factor
Answer: d

32. Spacers are provided between adjacent coils
(a) to provide free passage to the cooling oil
(b) to insulate the coils from each other
(c) both (a) and (b)
(d) none of the above
Answer: a

33. Greater the secondary leakage flux
(a) less will be the secondary induced e.m.f.
(b) less will be the primary induced e.m.f.
(c) less will be the primary terminal voltage
(d) none of the above
Answer: a

34. The purpose of providing iron core in a step-up transformer is
(a) to provide coupling between primary and secondary
(b) to increase the magnitude of mutual flux
(c) to decrease the magnitude of mag-netizing current
(d) to provide all above features
Answer: c

35. The power transformer is a constant
(a) voltage device
(b) current device
(c) power device
(d) main flux device
Answer: d

36. Two transformers operating in parallel will share the load depending upon their
(a) leakage reactance
(b) per unit impedance
(c) efficiencies
(d) ratings
Answer: b

37. If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be
(a) R2/VK
(b) R2IK2
(c) R22!K2
(d) R22/K
Answer: b

38. What will happen if the transformers working in parallel are not connected with regard to polarity ?
(a) The power factor of the two trans-formers will be different from the power factor of common load
(b) Incorrect polarity will result in dead short circuit
(c) The transformers will not share load in proportion to their kVA ratings
(d) none of the above
Answer: b

39. If the percentage impedances of the two transformers working in parallel are different, then
(a) transformers will be overheated
(b) power factors of both the transformers will be same
(c) parallel operation will be not possible
(d) parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load
Answer: d

40. In a transformer the tappings are generally provided on
(a) primary side
(b) secondary side
(c) low voltage side
(d) high voltage side
Answer: c

41. The use of higher flux density in the transformer design
(a) reduces weight per kVA
(6) reduces iron losses
(c) reduces copper losses
(d) increases part load efficiency
Answer: a

42. The chemical used in breather for transformer should have the quality of
(a) ionizing air
(b) absorbing moisture
(c) cleansing the transformer oil
(d) cooling the transformer oil.
Answer: b

43. The chemical used in breather is
(a) asbestos fiber
(b) silica sand
(c) sodium chloride
(d) silica gel
Answer: d

44. An ideal transformer has infinite values of primary and secondary inductances. The statement is
(a) true
(b) false
Answer: b

45. The transformer ratings are usually expressed in terms of
(a) volts
(b) amperes
(c) kW
(d) kVA
Answer: d

46. The noise resulting from vibrations of laminations set by magnetic forces, is termed as
(a) magnetostrication
(b) boo
(c) hum
(d) zoom
Answer: c

47. Hysteresis loss in a transformer varies as CBmax = maximum flux density)
(a) Bmax
(b) Bmax1-6
(C) Bmax1-83
(d) B max
Answer: b

48. Material used for construction of transformer core is usually
(a) wood
(b) copper
(c) aluminium
(d) silicon steel
Answer: d

49. The thickness of laminations used in a transformer is usually
(a) 0.4 mm to 0.5 mm
(b) 4 mm to 5 mm
(c) 14 mm to 15 mm
(d) 25 mm to 40 mm
Answer: a

50. The function of conservator in a transformer is
(a) to project against’internal fault
(b) to reduce copper as well as core losses
(c) to cool the transformer oil
(d) to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings
Answer: d

51. The highest voltage for transmitting electrical power in India is
(a) 33 kV.
(6) 66 kV
(c) 132 kV
(d) 400 kV
Answer: d

52. In a transformer the resistance between its primary and secondary is
(a) zero
(b) 1 ohm
(c) 1000 ohms
(d) infinite
Answer: d

53. A transformer oil must be free from
(a) sludge
(b) odour
(c) gases
(d) moisture
Answer: d

54. A Buchholz relay can be installed on
(a) auto-transformers
(b) air-cooled transformers
(c) welding transformers
(d) oil cooled transformers
Answer: d

55. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds
(a) 50°C
(b) 80°C
(c) 100°C
(d) 150°C
Answer: d

56. The main reason for generation of harmonics in a transformer could be
(a) fluctuating load
(b) poor insulation
(c) mechanical vibrations
(d) saturation of core
Answer: d

57. Distribution transformers are generally designed for maximum efficiency around
(a) 90% load
(b) zero load
(c) 25% load
(d) 50% load
Answer: d

58. Which of the following property is not necessarily desirable in the material for transformer core ?
(a) Mechanical strength
(6) Low hysteresis loss
(c) High thermal conductivity
(d) High permeability
Answer: c

59. Star/star transformers work satisfactorily when
(a) load is unbalanced only
(b) load is balanced only
(c) on balanced as well as unbalanced loads
(d) none of the above
Answer: b

60. Delta/star transformer works satisfactorily when
(a) load is balanced only
(b) load is unbalanced only
(c) on balanced as well as unbalanced loads
(d) none of the above
Answer: c

61. Buchholz’s relay gives warning and protection against
(a) electrical fault inside the transformer itself
(b) electrical fault outside the transformer in outgoing feeder
(c) for both outside and inside faults
(d) none of the above
Answer: a

62. The magnetising current of a transformer is usually small because it has
(a) small air gap
(b) large leakage flux
(c) laminated silicon steel core
(d) fewer rotating parts
Answer: a

63. Which of the following does not change in an ordinary transformer ?
(a) Frequency
(b) Voltage
(c) Current
(d) Any of the above
Answer: a

64. Which of the following properties is not necessarily desirable for the material for transformer core ?
(a) Low hysteresis loss
(b) High permeability
(c) High thermal conductivity
(d) Adequate mechanical strength
Answer: c

65. The leakage flux in a transformer depends upon
(a) load current
(b) load current and voltage
(c) load current, voltage and frequency
(d) load current, voltage, frequency and power factor
Answer: a

66. The path of the magnetic flux in transformer should have
(a) high reluctance
(b) low reactance
(c) high resistance
(d) low resistance
Answer: b

67. Noise level test in a transformer is a
(a) special test
(b) routine test
(c) type test
(d) none of the above
Answer: c

68. Which of the following is not a routine test on transformers ?
(a) Core insulation voltage test
(b) Impedance test
(c) Radio interference test
(d) Polarity test
Answer: c

69. A transformer can have zero voltage regulation at
(a) leading power factor
(b) lagging power factor
(c) unity power factor
(d) zero power factor
Answer: a

70. Helical coils can be used on
(a) low voltage side of high kVA transformers
(b) high frequency transformers
(c) high voltage side of small capacity transformers
(d) high voltage side of high kVA rating transformers
Answer: a

71. Harmonics in transformer result in
(a) increased core losses
(b) increased I2R losses
(c) magnetic interference with communication circuits
(d) all of the above
Answer: d

72. The core used in high frequency transformer is usually
(a) copper core
(b) cost iron core
(c) air core
(d) mild steel core
Answer: c

73. The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be
(a) 6400 W
(b) 1600 W
(c) 800 W
(d) 400 W
Answer: d

1.74. The value of flux involved m the e.m.f. equation of a transformer is
(a) average value
(b) r.m.s. value
(c) maximum value
(d) instantaneous value
Answer: c

L.75. Silicon steel used in laminations mainly reduces
(a) hysteresis loss
(b) eddy current losses
(c) copper losses
(d) all of the above
Answer: a

76. Which winding of the transformer has less cross-sectional area ?
(a) Primary winding
(b) Secondary winding
(c) Low voltage winding
(d) High voltage winding
Answer: d

77. Power transformers are generally designed to have maximum efficiency around
(a) no-load
(b) half-load
(c) near full-load
(d) 10% overload
Answer: c

.78. Which of the following is the main advantage of an auto-transformer over a two winding transformer ?
(a) Hysteresis losses are reduced
(b) Saving in winding material
(c) Copper losses are negligible
(d) Eddy losses are totally eliminated
Answer: b

79. During short circuit test iron losses are negligible because
(a) the current on secondary side is negligible
(b) the voltage on secondary side does not vary
(c) the voltage applied on primary side is low
(d) full-load current is not supplied to the transformer
Answer: c

80. Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
(a) short-circuiting of the secondaries
(b) power factor of one of the transformers is leading while that of the other lagging
(c) transformers having higher copper losses will have negligible core losses
(d) loading of the transformers not in proportion to their kVA ratings
Answer: d

81. The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and
night is taken care of by which part of transformer
(a) Conservator
(b) Breather
(c) Bushings
(d) Buchholz relay
Answer: a

82. An ideal transformer is one which has
(a) no losses and magnetic leakage
(b) interleaved primary and secondary windings
(c) a common core for its primary and secondary windings
(d) core of stainless steel and winding of pure copper metal
(e) none of the above
Answer: a

83. When a given transformer is run at its rated voltage but reduced frequency, its
(a) flux density remains unaffected
(b) iron losses are reduced
(c) core flux density is reduced
(d) core flux density is increased
Answer: d

84. In an actual transformer the iron loss remains practically constant from noload to fullload because
(a) value of transformation ratio remains constant
(b) permeability of transformer core remains constant
(c) core flux remains practically constant
(d) primary voltage remains constant
(c) secondary voltage remains constant
Answer: c

85. An ideal transformer will have maximum efficiency at a load such that
(a) copper loss = iron loss
(b) copper loss < iron loss
(c) copper loss > iron loss
(d) none of the above
Answer: a

86. If the supply frequency to the transformer is increased,”the iron loss will
(a) not change
(b) decrease
(c) increase
(d) any of the above
Answer: c

87. Negative voltage regulation is indicative that the load is
(a) capacitive only
(b) inductive only
(c) inductive or resistive
(d) none of the above
Answer: a

88. Iron loss of a transformer can be measured by
(a) low power factor wattmeter
(b) unity power factor wattmeter
(c) frequency meter
(d) any type of wattmeter
Answer: a

89. When secondary of a current transformer is open-circuited its iron core will be
(a) hot because of heavy iron losses taking place in it due to high flux density
(b) hot because primary will carry heavy current
(c) cool as there is no secondary current
(d) none of above will happen
Answer: a

90. The transformer laminations are insulated from each other by
(a) mica strip
(6) thin coat of varnish
(c) paper
(d) any of the above
Answer: b

91. Which type of winding is used in 3phase shell-type transformer ?
(a) Circular type
(b) Sandwich type
(c) Cylindrical type
(d) Rectangular type
Answer: b

92. During open circuit test of a transformer
(a) primary is supplied rated voltage
(b) primary is supplied full-load current
(c) primary is supplied current at reduced voltage
(d) primary is supplied rated kVA
Answer: a

93. Open circuit test on transformers is conducted to determine
(a) hysteresis losses
(b) copper losses
(c) core losses
(d) eddy current losses
Answer: c

94. Short circuit test on transformers is conducted to determine
(a) hysteresis losses
(b) copper losses
(c) core losses
(d) eddy current losses
Answer: b

95. For the parallel operation of single phase transformers it is necessary that they should have
(a) same efficiency
(b) same polarity
(c) same kVA rating
(d) same number of turns on the secondary side.
Answer: b

96. The transformer oil should have _____ volatility and _____ viscosity.
(a) low,low
(b) high,high
(c) low,high
(d) high,low
Answer: a

97. The function of breather in a transformer is
(a) to provide oxygen inside the tank
(b) to cool the coils during reduced load
(c) to cool the transformer oil
(d) to arrest flow of moisture when outside air enters the transformer
Answer: d

98. The secondary winding of which of the following transformers is always kept closed ?
(a) Step-up transformer
(b) Step-down transformer
(c) Potential transformer
(d) Current transformer
Answer: d

99. The size of a transformer core will depend on
(a) frequency
(b) area of the core
(c) flux density of the core material
(d) (a) and (b) both
Answer: d

100. N atural air coo ling is generally restricted for transformers up to
(a) 1.5 MVA
(b) 5 MVA
(c) 15 MVA
(d) 50 MVA
Answer: a

101. A shell-type transformer has
(a) high eddy current losses
(b) reduced magnetic leakage
(c) negligibly hysteresis losses
(d) none of the above
Answer: b

102. A transformer can have regulation closer to zero
(a) on full-load
(b) on overload
(c) on leading power factor
(d) on zero power factor
Answer: c

103. A transformer transforms
(a) voltage
(b) current
(c) current and voltage
(d) power
Answer: d

104. Which of the following is not the standard voltage for power supply in India ?
(a) llkV
(b) 33kV
(c) 66 kV
(d) 122 kV
Answer: d

105. Reduction in core losses and increase in permeability are obtained with transformer employing
(a) core built-up of laminations of cold rolled grain oriented steel
(b) core built-up of laminations of hot rolled sheet
(c) either of the above
(d) none of the above
Answer: a

106. In a power or distribution transformer about 10 per cent end turns are heavily insulated
(a) to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns
(b) to absorb the line surge voltage and save the winding of transformer from damage
(c) to reflect the line surge and save the winding of a transformer from damage
(d) none of the above
Answer: a

107. For given applied voltage, with the increase in frequency of the applied voltage
(a) eddy current loss will decrease
(b) eddy current loss will increase
(c) eddy current loss will remain unchanged
(d) none of the above
Answer: c

108. Losses which occur in rotating electric machines and do not occur in trans formers are
(a) friction and windage losses
(b) magnetic losses
(c) hysteresis and eddy current losses
(d) copper losses
Answer: a

109. In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are
(a) hysteresis and eddy current losses
(b) friction and windage losses
(c) copper losses
(d) none of the above
Answer: a

110. Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and
drawing a current of 10 A from 200 V A.C. supply is incorrect ?
(a) Its secondary current is 5 A
(b) Its secondary voltage is 400 V
(c) Its rating is 2 kVA
(d) Its secondary current is 20 A
(e) It is a step-up transformer
Answer: d

111. The secondary of a current transformer is always short-circuited under operating conditions because it
(a) avoids core saturation and high voltage induction
(b) is safe to human beings
(c) protects the primary circuit
(d) none of the above
Answer: a

112. In a transformer the resistance between its primary and secondary should be
(a) zero
(b) 10 Q
(c) 1000 Q
(d) infinity
Answer: d

113. A good voltage regulation of a transformer means
(a) output voltage fluctuation from no load to full load is least
(b) output voltage fluctuation with power factor is least
(c) difference between primary and secondary voltage is least
(d) difference between primary and secondary voltage is maximum
Answer: a

114. For a transformer, operating at constant load current, maximum efficiency will occur at
(a) 0.8 leading power factor
(b) 0.8 lagging power factor
(c) zero power factor
(d) unity power factor
Answer: d

115. Which of the following protection is normally not provided on small distribution transformers ?
(a) Overfluxing protection
(b) Buchholz relay
(c) Overcurrent protection
(d) All of the above
Answer: b

116. Which of the following acts as a protection against high voltage surges due to lightning and switching ?
(a) Horn gaps
(b) Thermal overload relays
(c) Breather
(d) Conservator
Answer: a

117. The efficiency of two identical transformers under load conditions can be determined by
(a) short-circuit test
(b) back-to-back test
(c) open circuit test
(d) any of the above
Answer: b

118. Which of the following insulating materials can withstand the highest temperature safely ?
(a) Cellulose
(b) Asbestos
(c) Mica
(d) Glass fibre
Answer: c

119. Which of the following parts of a transformer is visible from outside ?
(a) Bushings
(b) Core
(c) Primary winding
(d) Secondary winding
Answer: a

120. The noise produced by a transformer is termed as
(a) zoom
(b) hum
(c) ringing
(d) buzz
Answer: b

121. Which of the following loss in a transformer is zero even at full load ?
(a) Core loss
(b) Friction loss
(c) Eddy current loss
(d) Hysteresis loss
Answer: b

122. Which of the following is the most likely source of harmonics in a transformer ?
(a) poor insulation
(b) Overload
(c) loose connections
(d) Core saturation
Answer: d

123. If a transformer is continuously operated the maximum temperature rise will occur in
(a) core
(b) windings
(c) tank
(d) any of the above
Answer: b

124. The hum in a transformer is mainly attributed to
(a) load changes
(b) oil in the transformer
(c) magnetostriction
(d) mechanical vibrations
Answer: c

125. The maximum load that a power transformer can carry is limited by its
(a) temperature rise
(b) dielectric strength of oil
(c) voltage ratio
(d) copper loss
Answer: c

126. The efficiency of a transformer, under heavy loads, is comparatively low because
(a) copper loss becomes high in proportion to the output
(b) iron loss is increased considerably
(c) voltage drop both in primary and secondary becomes large
(d) secondary output is much less as compared to primary input
Answer: a

127. An open-circuit test on a transformer is conducted primarily to measure
(a) insulation resistance
(b) copper loss
(c) core loss
(d) total loss
(e) efficiency
(f) none of the above
Answer: c

128. A no-load test is performed on a transformer to determine
(a) core loss
(b) copper loss
(c) efficiency
(d) magnetising current
(e) magnetising current and loss
Ans: e

129. The voltage transformation ratio of a transformer is equal to the ratio of
(a) primary turns to secondary turns
(b) secondary current to primary current
(c) secondary induced e.m.f. to primary induced e.m.f.
(d) secondary terminal voltage to primary applied voltage
Answer: c

130. Part of the transformer which is most subject to damage from overheating is
(a) iron core
(b) copper winding
(c) winding insulation
(d) frame or case
(e) transformer tank
Answer: c

136. If a transformer is switched on to a voltage more than the rated voltage
(a) its power factor will deteriorate
(b) its power factor will increase
(c) its power factor will remain unaffected
(d) its power factor will be zero
Answer: a

137. Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is
(a) approximately equal to one
(b) less than one
(c) great than one
(d) none of the above
Answer: a

138. Minimum voltage regulation occurs when the power factor of the load is
(a) unity
(b) lagging
(c) leading
(d) zero
Answer: c

139. In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of
(a) less than 15 A
(b) more than 15 A
(c) 15 A
(d) none of the above
Answer: a

140. The efficiencies of transformers compared with that of electric motors of the same power are
(a) about the same
(6) much smaller
(c) much higher
(d) somewhat smaller
(e) none of the above
Answer: c

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