Control system mcq part -2

1.--- increases the steady state accuracy.
(a) Integrator
(b) Differentiator
(c) Phase lead compensator
(d) Phase lag compensator

Ans: a

2. A.C. servomotor resembles
(a) two phase induction motor
(b) Three phase induction motor
(c) direct current series motor
(d) universal motor

Ans: a

3. As a result of introduction of negative feedback which of the following will not decrease ?
(a) Band width
(b) Overall gain
(c) Distortion
(d) Instability

Ans: a

4. Regenerative feedback implies feedback with
(a) oscillations
(b) step input
(c) negative sign
(d) positive sign

Ans: d

5. The output of a feedback control system must be a function of
(a) reference and output
(b) reference and input
(e) input and feedback signal
(d) output and feedback signal

Ans: a

6.--- is an open loop control system.
(a) Ward Leonard control
(b) Field controlled D.C. motor
(c) Stroboscope
(d) Metadyne

Ans: b

7. A control system with excessive noise, is likely to suffer from
(a) saturation in amplifying stages
(b) loss of gain
(c) vibrations
(d) oscillations

Ans: a

8. Zero initial condition for a system means
(a) input reference signal is zero
(b) zero stored energy
(c) ne initial movement of moving parts
(d) system is at rest and no energy is stored in any of its components

Ans: d

9. Transfer function of a system is used to calculate which of the following ?
(a) The order of the system
(b) The time constant
(c) The output for any given input
(d) The steady state gain

Ans: c

10. The band width, in a feedback amplifier.
(a) remains unaffected
(b) decreases by the same amount as the gain increase
(c) increases by the sane saaaajajt as the gain decrease
(d) decreases by the same amount as the gain decrease

Ans: c

11. On which of the following factors does the sensitivity of a closed
loop system to gain changes and
load disturbances depend ?
(a) Frequency
(b) Loop gain
(c) Forward gain
(d) All of the above

Ans: d

12. The transient response, with feedback system
(a) rises slowly
(b) rises quickly
(c) decays slowly
(d) decays quickly

Ans: d

13. The second derivative input signals modify which of the following ?
(a) The time constant of the system
(b) Damping of the system
(c) The gain of the system
(d) The time constant and suppress the oscillations
(e) None of the above
Ans: d

14. Which of the following statements is correct for any closed loop system ?
(a) All the co-efficients can have zero value
(6) All the co-efficients are always non-zero
(c) Only one of the static error co-efficients has a finite non-zero value
(d) None of the above

Ans: c

15. Which of the following statements is correct for a system with gain
margin close to unity or a phase margin close to zero ?
(a) The system is relatively stable
(b) The system is highly stable
(c) The system is highly oscillatory
(d) None of the above

Ans: c

16. Due to which of the following reasons excessive bond width in control systems should be avoided ?
(a) It leads to slow speed of response
(b) It leads to low relative stabilit
(c) Noise is proportional to band width
(d) None of the above

Ans: c

17. In a stable control system backlash can cause which of the following
?
(a) Underdamping
(b) Overdamping
(c) Poor stability at reduced values of open loop gain
(d) Low-level oscillations

Ans: d

18. In an automatic control system which of the following elements is not used ?
(a) Error detector
(b) Final control element
(c) Sensor
(d) Oscillator

Ans: d

19. In a control system the output of the controller is given to
(a) final control element
(b) amplifier
(c) comparator
(d) sensor
(e) none of the above

Ans: a

40. A controller, essentially, is a
(a) sensor
(b) clipper
(c) comparator
(d) amplifier

Ans: c

Cable mcq part -3

1. The advantage of cables over overhead transmission lines is
(a) easy maintenance
(b) low cost
(c) can be used in congested areas
(d) can be used in high voltage circuits

Ans: c

2. The thickness of metallic shielding on cables is usually
(a) 0.04 mm
(b) 0.2 to 0.4 mm
(e) 3 to 5 mm
(d) 40 to 60 mm

Ans: a

3. Cables for 220 kV lines are invariably
(a) mica insulated
(b) paper insulated
(c) compressed oil or compressed gas insulated
(d) rubber insulated
(e) none of the above

Ans: c

14. Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ?
(a) Polyvinyle chloride
(b) Vulcanised rubber
(c) Impregnated paper
(d) Compressed SFe gas
(e) none of the above

Ans: d

5. If a power cable and a communication cable are to run parallel the minimum distance
between the two, to avoid interference, should be
(a) 2 cm
(b) 10 cm
(c) 50 cm
(d) 400 cm

Ans: c

6. Copper as conductor for cables is used as
(a) annealed
(b) hardened and tempered
(c) hard drawn
(d) alloy with chromium
Ans: a

7. The insulating material should have
(a) low permittivity
(b) high resistivity
(c) high dielectric strength
(d) all of the above

Ans: d

8. The advantage of oil filled cables is
(a) more perfect impregnation
(b) smaller overall size
(c) no ionisation, oxidation and formation of voids
(d) all of the above
Ans: d

9. The disadvantage with paper as insulating material is
(a) it is hygroscopic
(6) it has high capacitance
(c) it is an organic material
(d) none of the above

Ans: a

10. The breakdown voltage of a cable depends on
(a) presence of moisture
(b) working temperature
(c) time of application of the voltage
(d) all of the above

Ans: d

11. It is difficult to maintain oil filled cables.
(a) Yes
(b) No

Ans: a

11. In capacitance grading a homogeneous dielectric is used.
(a) Yes
(b) No

Ans: b

12. In congested areas where excavation is expensive and inconvenient 'draw in system'
of laying of underground cables is often adopted.
(a) Yes
(b) No

Ans: a

13. Natural rubber is obtained from milky sap of tropical trees.
(a) Yes
(b) No

Ans: a

14. Rubber is most commonly used insulation in cables.
(a) Yes
(b) No

Ans: a

15. Polyethylene has very poor dielectric and ageing properties.
(a) Yes
(b) No
Ans: b

16. The metallic sheath may be made of lead or lead alloy or of aluminium.
(a) Yes
(b) No
Ans: b

Cable mcq part -2

1.In the cables, the location of fault is usually found out by comparing
(a) the resistance of the conductor
(b) the inductance of conductors
(c) the capacitances of insulated conductors
(d) all above parameters

Ans: c

2. In capacitance grading of cables we use a dielectric.
(a) composite
(b) porous
(c) homogeneous
(d) hygroscopic

Ans: a

3. Pressure cables are generally not used beyond
(a) 11 kV
(b) 33 kV
(c) 66 kV
(d) 132 kV

Ans: c

4. The material for armouring on cable is usually
(a) steel tape
(b) galvanised steel wire
(c) any of the above
(d) none of the above

Ans: c

5. Cables, generally used beyond 66 kV are
(a) oil filled
(b) S.L. type
(c) belted
(d) armoured

Ans: a

6. The relative permittivity of rubber is
(a) between 2 and 3
(b) between 5 and 6
(c) between 8 and 10
(d) between 12 and 14

Ans: a

7. Solid type cables are considered unreliable beyond 66 kV because
(a) insulation may melt due to higher temperature
(b) skin effect dominates on the conduc¬tor
(c) of corona loss between conductor and sheath material
(d) there is a danger of breakdown of insulation due to the presence of voids

Ans: d

8. If the length of a cable is doubled, its capacitance
(a) becomes one-fourth
(b) becomes one-half
(c) becomes double
(d) remains unchanged
Ans: c

9. In cables the charging current
(a) lags the voltage by 90°
(b) leads the voltage by 90°
(c) lags the voltage by 180°
(d) leads the voltage by 180°

Ans: b

10. A certain cable has an insulation of relative permittivity 4. If the insulation is replaced
by one of relative permittivity 2, the capacitance of the cable will become
(a) one half
(6) double
(c) four times
(d) none of the above

Ans: a

11. If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the
dielectric strength of insulation should be
(a) 5 kV/mm
(b) 10 kV/mm
(a) 15 kV/mm
(d) 30 kV/mm

Ans: b

12. In the cables, sheaths are used to
(a) prevent the moisture from entering the cable
(b) provide enough strength
(e) provide proper insulation
(d) none of the above

Ans: a

13. The intersheaths in the cables are used to
(a) minimize the stress
(b) avoid the requirement of good insulation
(c) provide proper stress distribution
(d) none of the above

Ans: c

14. The electrostatic stress in underground cables is
(a) same at the conductor and the sheath
(b) minimum at the conductor and maximum at the sheath
(c) maximum at the conductor and minimum at the sheath
(d) zero at the conductor as well as on the sheath
(e) none of the above

Ans: c

15. The breakdown of insulation of the cable can be avoided economically by the use of
(a) inter-sheaths
(b) insulating materials with different dielectric constants
(c) both (a) and (b)
(d) none of the above

Ans: c

16. The insulation of the cable decreases with
(a) the increase in length of the insulation
(b) the decrease in the length of the insulation
(c) either (a) or (b)
(d) none of the above

Ans: a

17. A cable carrying alternating current has
(a) hysteresis losses only
(b) hysteresis and leakage losses only
(c) hysteresis, leakage and copper losses only
(d) hysteresis, leakage, copper and friction losses

Ans: b

18. In a cable the voltage stress is maximum at
(a) sheath
(6) insulator
(e) surface of the conductor
(d) core of the conductor

Ans: d

19. Capacitance grading of cable implies
(a) use of dielectrics of different permeabilities
(b) grading according to capacitance of cables per km length
(c) cables using single dielectric in different concentrations
(d) capacitance required to be introduced at different lengths to counter the effect of
inductance
(e) none of the above

Ans: a

20. Underground cables are laid at sufficient depth
(a) to minimise temperature stresses
(b) to avoid being unearthed easily due to removal of soil
(c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc.
(d) for all of the above reasons

Ans: c

Transmission and distribution mcq part - 3

1. Transmission line insulators are made of
(a) glass
(b) porcelain
(c) iron
(d) P.V.C.

Ans: b

2. The material commonly used for sheaths of underground cables is
(a) lead
(b) rubber
(c) copper
(d) iron

Ans: a

3. The minimum clearance between the ground and a 220 kV line is about
(a) 4.3 m
(b) 5.5 m
(c) 7.0 m
(d) 10.5 m

Ans: c

4. The spacing between phase conductors of a 220 kV line is approximately equal to
(a) 2 m
(b) 3.5 m
(c) 6 m
(d) 8.5 m

Ans: c

5. Large industrial consumers are supplied electrical energy at
(a) 400 V
(b) 11 kV
(c) 66 kV
(d) 400 kV

Ans: c

6. In a D.C. 3-wire distribution system, balancer fields are cross-connected in order to
(a) boost the generated voltage
(b) balance loads on both sides of the neutral
(c) make both machine^ run as unloaded motors
(d) equalize voltages on the positive and negative outers
Ans: d

7. In a D.C. 3-wire distributor using balancers and having unequal loads on the two sides
(a) both balancers run as generators
(b) both balancers run as motors
(c) balancer connected to lightly- loaded side runs as a motor
(d) balancer connected to heavily- loaded side runs as a motor

Ans: c

8. Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is
increased 100 percent, saving in copper is
(a) 25 percent
(b) 50 percent
(c) 75 percent
(d) 100 percent

Ans: b

9. A uniformly-loaded D.C. distributor is fed at both ends with equal voltages. As
compared to a similar distributor fed at one end only, the drop at the middle point is
(a) one-fourth
(b) one-third
(c) one-half
(d) twice
(e) none of the above

Ans: a

10. As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum
voltage to earth uses only
(a) 31.25 percent of copper
(b) 33.3 percent of copper
(c) 66.7 percent of copper
(d) 125 percent of copper

Ans: a

11. Which of the following is usually not the generating voltage ?
(a) 6.6 kV
(b) 8.8 kV
(c) 11 kV
(d) 13.2 kV

Ans: b

12. For an overhead line, the surge impedance is taken as
(a) 20-30 ohms
(b) 70—80 ohms
(c) 100—200 ohms
(d) 500—1000 ohms
(e) none of the above

Ans: c

13. The presence of ozone due to corona is harmful because it
(a) reduces power factor
(b) corrodes the material
(c) gives odour
(d) transfer energy to the ground
(e) none of the above

Ans: b

14. A feeder, in a transmission system, feeds power to
(a) distributors
(b) generating stations
(c) service mains
(d) all of the above

Ans: a

15. The power transmitted will be maximum when
(a) corona losses are minimum
(b) reactance is high
(c) sending end voltage is more
(d) receiving end voltage is more

Ans: c

16. A 3-phase 4 wire system is commonly used on
(a) primary transmission
(b) secondary transmission
(c) primary distribution
(d) secondary distribution

Ans: d

17. Which of the following materials is used for overhead transmission lines ?
(a) Steel cored aluminium
(b) Galvanised steel
(c) Cadmium copper
(d) Any of the above

Ans: d

18. Which of the following is not a constituent for making porcelain insulators ?
(a) Quartz
(b) Kaolin
(c) Felspar
(d) Silica

Ans: d

19. There is a greater possibility of occurence of corona during
(a) dry weather
(b) winter
(c) summer heat
(d) humid weather
(e) none of the above

Ans: d

20. Which of the following relays is used on long transmission lines ?
(a) Impedance relay
(b) Mho's relay
(c) Reactance relay
(d) None of the above

Ans: b

Transmission and distribution mcq part -2

1. Which of the following is the source of heat generation in the cables ?
(a) Dielectric losses in cable insulation
(b) losses in the conductor
(c) Losses in the metallic sheathings and armourings
(d) All of the above

Ans: d

2. Due to which of the following reasons the cables should not be operated too hot ?
(a) The oil may loose its viscosity and it may start drawing off from higher levels
(b) Expansion of the oil may cause the sheath to burst
(c) Unequal expansion may create voids in the insulation which will lead to ionization
(d) The thermal instability may rise due to the rapid increase of dielectric losses with
temperature
(e) All of the above

Ans: e

3. Which of the following D.C. distribution system is the simplest and lowest in first cost
?
(a) Radial system
(b) Ring system
(c) Inter-connected system
(d) None of the above
Ans: a

4. A booster is a
(a) series wound generator
(b) shunt wound generator
(c) synchronous generator
(d) none of the above

Ans: a

5. Besides a method of trial and error, which of the following methods is employed for
solution of network problems in interconnected system ?
(a) Circulating current method
(b) Thevenin's theorem
(c) Superposition of currents
(d) Direct application of Kirehhoffs laws
(e) All of the above

Ans: e

6. Which of the following faults is most likely to occur in cables ?
(a) Cross or short-circuit fault
(b) Open circuit fault
(c) Breakdown of cable insulation
(d) All of the above

Ans: d

7. The cause of damage to the lead sheath of a cable is
(a) crystallisation of the lead through vibration
(b) chemical action on the lead when buried in the earth
(c) mechanical damage
(d) all of the above

Ans: d

8. The voltage of the single phase supply to residential consumers is
(a) 110 V
(b) 210 V
(c) 230 V
(d) 400 V

Ans: c

9. Most of the high voltage transmission lines in India are
(a) underground
(b) overhead
(c) either of the above
(d) none of the above

Ans: b

10. The distributors for residential areas are
(a) single phase
(b) three-phase three wire
(c) three-phase four wire
(d) none of the above

Ans: c

11. The conductors of the overhead lines are
(a) solid
(b) stranded
(c) both solid and stranded
(d) none of the above

Ans: b

12. High voltage transmission lines use
(a) suspension insulators
(b) pin insulators
(c) both (a) and (b)
(d) none of the above

Ans: a

13. Multicore cables generally use
(a) square conductors
(b) circular conductors
(c) rectangular conductors
(d) sector-shaped conductors
(e) none of the above

Ans: d

14. Distribution lines in India generally use
(a) wooden poles
(b) R.C.C. poles
(c) steel towers
(d) none of the above

Ans: b

15. The material commonly used for insulation in high voltage cables is
(a) lead
(b) paper
(c) rubber
(d) none of the above

Ans: b

16. The loads on distributors systems are generally
(a) balanced
(b) unbalanced
(c) either of the above
(d) none of the above

Ans: b

17. The power factor of industrial loads is generally
(a) unity
(b) lagging
(c) leading
(d) zero

Ans: b

18. Overhead lines generally use
(a) copper conductors
(b) all aluminium conductors
(c) A.C.S.R. conductors
(d) none of these

Ans: c

19. In transmission lines the cross-arms are made of
(a) copper
(b) wood
(c) R.C.C.
(d) steel

Ans: d

20. The material generally used for armour of high voltage cables is
(a) aluminium
(b) steel
(c) brass
(d) copper

Ans: b

Synchronous motor mcq part-3

1. Synchronous motors are
(a) not-self starting
(b) self-starting
(c) essentially self-starting
(d) none of the above

Ans: a

2. The standard full-load power factor ratings for synchronous motors are
(a) zero or 0.8 leading
(b) unity or 0.8 lagging
(c) unity or 0.8 leading
(d) unity or zero

Ans: c

3. A synchronous motor running with normal excitation adjusts to load increases essentially by increase in
(a) back e.m.f.
(b) armature current
(c) power factor
(d) torque angle

Ans: b

4. A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because
(a) synchronous motor has no slip
(b) stator supply is not required to produce magnetic field
(c) mechanical load on the rotor remains constant
(d) synchronous motor has large airgap

Ans: b

5. A synchronous motor working at leading power factor can be used as
(a) voltage booster
(b) phase advancer
(c) noise generator
(d) mechanical synchronizer

Ans: b

6. Slip rings are usually made of
(a) carbon or graphite
(b) brass or steel
(c) silver or gold
(d) copper or aluminium

Ans: b

7. An over excited synchronous motor is used for
(a) fluctuating loads
(b) variable speed loads
(c) low torque loads
(d) power factor corrections

Ans: d

8. When the voltage applied to a synchronous motor is increased, which of the following will reduce ?
(a) Stator flux
(b) Pull in torque
(c) Both (a) and (b)
(d) None of the above

Ans: d

11. The efficiency of a properly designed synchronous motor will usually fall in range
(a) 60 to 70% (6) 75 to 80%
(c) 85 to 95% (d) 99 to 99.5%

Ans: c

12. To limit the operating temperature an electrical machine should have proper
(a) voltage rating
(b) current rating
(c) power factor
(d) speed

Ans: b

13. Slip-rings in a synchronous motor carry
(a) direct current
(b) alternating current
(c) no current
(d) all of the above

Ans: a

14. A synchronous machine with large air gap has
(a) a higher value of stability limit
(6) a small value of inherent regulation
(c) a higher synchronizing power which makes the machine less sensitive to load variations
(d) all of the above

Ans: d

15. The armature current of the synchronous motor has higher values for
(a) high excitation only
(b) low excitation only
(c) both (a) and (b)
(d) none of the above

Ans: c

16. In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately
(a) one-third
(b) twice
(c) thrice
(d) six times
(e) nine times

Ans: c

17. The angle between the rotating stator flux and rotor poles is called angle.
(a) torque
(b) obtuse
(c) synchronizing
(d) power factor

Ans: a

18. Which of the following methods is used to start a synchronous motor ?
(a) Damper winding
(b) Star-delta starter
(c) Damper winding in conjunction with star-delta starter
(d) Resistance starter in the armature circuit

Ans: c

19. When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
(a) inductor motor torque
(b) induction generator torque
(c) synchronous motor torque
(d) d.c. motor toque
(e) none of the above

Ans: b

20. An important advantage of a synchronous motor over wound round induction motor is that
(a) its power factor may be varied at will
(b) its speed is independent of supply frequency
(c) its speed may be controlled more easily
(d) none of the above

Ans: a

Synchronous motor mcq part -2

1. If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is
(a) 2
(b) 3
(c) 4
(d) 6

Ans: b

2. For V-curves for a synchronous motor the graph is drawn between
(a) field current and armature current
(b) terminal voltage and load factor
(c) power factor and field current
(d) armature current and power factor

Ans: a

3. The back e.m.f. of a synchronous motor depends on
(a) speed
(b) load
(c) load angle
(d) all of the above

Ans: c

4. A synchronous motor can operate at
(a) lagging power factor only
(6) leading power factor only
(c) unity power factor only
(d) lagging, leading and unity power factors

Ans: d

5. In a synchronous motor which loss varies with load ?
(a) Windage loss
(b) Bearing friction loss
(c) Copper loss
(d) Core loss

Ans: c

6. A synchronous motor can be made self starting by providing
(a) damper winding on rotor poles
(b) damper winding on stator
(c) damper winding on stator as well as rotor poles
(d) none of the above

Ans: d

7. The oscillations in a synchronous motor can be damped out by
(a) maintaining constant excitation
(b) running the motor on leading power factors
(c) providing damper bars in the rotor pole faces
(d) oscillations cannot be damped

Ans: c

8. The shaft of synchronous motor is made of
(a) mild steel
(b) chrome steel
(c) alnico
(d) stainless steel

Ans: a

9. When the field of a synchronous motor is under-excited, the power factor will be
(a) leading
(b) lagging
(c) unity
(d) zero

Ans: b

10. The speed regulation of a synchronous motor is always
(a) 1%                                                                                                                                (b) 0.5%
(c) positive
(d) zero

Ans: d

11. The percentage slip in case of a synchronous motor is
(a) 1%                                                                                                                               (b) 100%                                                                                                                             (c) 0.5%
(d) zero

Ans: d

12. The operating speed of a synchronous motor can be changed to new fixed value by
(a) changing the load
(b) changing the supply voltage
(c) changing frequency
(d) using brakes

Ans: c

13. A synchronous motor will always stop when
(a) supply voltage fluctuates
(b) load in motor varies
(c) excitation winding gets disconnected
(d) supply voltage frequency changes

Ans: c

14. riunting in a synchronous motor takes place
(a) when supply voltage fluctuates
(b) when load varies
(c) when power factor is unity
(d) motor is under loaded

Ans: b

15. When load on an over-excited or under excited synchronous*motor is increased, rate of change of its armature current as compared with that of power factor is
(a) more
(b) less
(c) equal
(d) twice

Ans: b

16. The rotor copper losses, in a synchronous motor, are met by
(a) d.c. source
(b) armature input
(c) motor input
(d) supply lines

Ans: a

17. The maximum power developed in a synchronous motor occurs at a coupling angle of
(a) 30°
(b) 60°
(c) 90°                                                                                                                                   (d) 180°

Ans: c

18. When the stator windings are connected in such a fashion that the number of poles are made half, the speed of
the rotor of a synchronous motor
(a) remains same as the original value
(b) decreases to half the original value
(c) tends to becomes zero
(d) increases to two times the original value

Ans: d

19. In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
(a) Universal motor
(b) Synchronous motor
(c) Induction motor
(d) Reluctance motor

Ans: b

20. Synchronsizingpower of a synchronous machine is
(a) direcly proportional to the synchronous reactance
(6) inversely proportional to the synchronous reactance
(a) equal to the synchronous reactance
(d) none of the above

Ans: b

Singal phase induction motor mcq part -3

1. In a two value capacitor motor, the capacitor used for running purposes is
(a) air capacitor
(b) paper spaced oilfilled type
(c) ceramic type
(d) a.c. electrolytic type

Ans: b

2. 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

Ans: a

3. 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

Ans: c

4. 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

Ans: c

5. Which of the following motors has highest starting torque ?
(a) Repulsion motor
(b) Shaped pole motor
(c) Capacitor-start motor
(d) Split-phase motor

Ans: c

6. The repulsion-start induction-run motor is used because of
(a) good power factor
(b) high efficiency
(c) minimum cost
(d) high starting torque

Ans: d

7. 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

Ans: a

8. 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

Ans: d

9. 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

Ans: c

10. 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

Ans: a

11. 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

Ans: c

12. 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

Ans: d

13. The speed of a universal motor is generally reduced by using
(a) gear trains
(b) V-belts
(c) brakes
(d) chains

Ans: a

14. 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

Ans: d

15. 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

Ans: a

16. 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

Ans: c

17. 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

Ans: c

18. Which motor is normally free from mechanical and magnetic vibrations ?
(a) Split phase motor
(b) Universal motor
(c) Hysteresis motor
(d) Shaded pole motor

Ans: c

19. 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

Ans: c

20. A reluctance motor
(a) is self-starting
(b) is constant speed motor
(c) needs no D.C. excitation
(d) all of the above

Ans: d

Singal phase induction motor mcq part-2

1. 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

Ans: b

2. Burning out of windings is due to
(a) short circuited capacitor
(b) capacitor value hiving changed
(c) open circuiting of capacitor
(d) none of the above

Ans: a

3. 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)

Ans: c

4. Short-circuiter is used in
(a) repulsion induction motor
(b) repulsion motor
(c) repulsion start induction run motor
(d) none of the above

Ans: c

5. 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%

Ans: d

6. 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

Ans: d

7. The power factor of a single-phase induction motor is usually
(a) lagging
(b) always leading
(c) unity
(d) unity to 0.8 leading

Ans: a

8. A shaded pole motor can be used for
(a) toys
(b) hair dryers
(c) circulators
(d) any of the above

Ans: d

9. A hysteresis motor works on the principle of
(a) hysteresis loss
(b) magnetisation of rotor
(c) eddy current loss
(d) electromagnetic induction

Ans: a

10. 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

Ans: b

11. For which of the applications a reluctance motor is preferred ?
(a) Electric shavers
(b) Refrigerators
(c) Signalling and timing devices
(d) Lifts and hoists

Ans: c

12. 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

Ans: c

13. 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

Ans: b

14. 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

Ans: c

15. A schrage motor can run on
(a) zero slip
(b) negative slip
(c) positive slip
(d) all of the above

Ans: d

16. A universal motor can run on
(a) A.C. only
(6) D.C. only
(c) either A.C. or D.C.
(d) none of the above

Ans: c

17. 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

Ans: a

18. 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

Ans: a

19. In split-phase motor iauxiliary 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

Ans: c

20. 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

Ans: d