Heating and Welding Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.   Which of the following is an advantage of heating by electricity ?
(a)     Quicker operation
(b)     Higher efficiency
(c)    Absence of flue gases
(d)    All of the above
Ans: d

2.   ________ has the highest value of thermal conductivity.
(a) Copper   
(b) Aluminium
(c) Brass   
(d) Steel
Ans: a

3. Which of the following heating methods has maximum power factor ?
(a)    Arc heating
(b)    Dielectric heating
(c)    Induction heating
(d)    Resistance heating
Ans: d

4    method has leading power factor
(a)     Resistance heating
(b)     Dielectric heating
(c)    Arc heating
(d)    Induction heating
Ans: b

5    is used for heating non-conducting materials.
(a)     Eddy current heating
(b)     Arc heating
(c)    Induction heating
(d)    Dielectric heating
Ans: d

6.    Which of the following methods of heating is not dependent on the frequency of supply ?
(a)     Induction heating
(b)     Dielectric heating
(c)    Electric resistance heating
(d)    All of the above
Ans: c

7.    When a body reflects entire radiation incident on it, then it is known as
(a)     white body       
(b)     grey body
(c)    black body
(d)    transparent body
Ans: a

8.    For the transmission of heat from one body to another
(a)     temperature of the two bodies must be different
(b)     both bodies must be solids
(c)    both bodies must be in contact
(d)    at least one of the bodies must have some source of heating
Ans: a

9.    Heat transfer by condition will not occur when
(a)     bodies are kept in vacuum
(b)     bodies are immersed in water
(c)    bodies are exposed to thermal radiations
(d)    temperatures of the two bodies are identical
Ans: d

10.    A perfect black body is one that
(a)     transmits all incident radiations
(b)     absorbs all incident radiations
(c)    reflects all incident radiations
(d)    absorbs, reflects and transmits all incident radiations
Ans: b

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Industrial Drives Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    The selection of an electric motor for any application depends on which of the following factors ?
(a)    Electrical characteristics
(b)    Mechanical characteristics
(c)    Size and rating of motors
(d)    Cost
(e)    All of the above
Ans: e

2.    For a particular application the type of electric-and control gear are determined by which of the following considerations ?
(a)    Starting torque
(b)    Conditions of environment
(c)    Limitation on starting current
(d)    Speed control range and its nature
(e)    All of the above
Ans: e

3.    Which ofthefollowingmotors is preferred for traction work ?
(a)     Universal motor
(b)     D.C. series motor
(c)    Synchronous motor
(d)    Three-phase induction motor
Ans:

4   Which of the following motors always starts on load ?
(a)     Conveyor motor
(b)     Floor mill motor
(c)    Fan motor
(d)    All of the above
Ans: d

5    is preferred for automatic drives.
(a)     Squirrel cage induction motor
(b)     Synchronous motors
(c)    Ward-Leonard controlled D.C. motors
(d)    Any of the above
Ans: c

6. When the load is above _____ a synchronous motor is found to be more economical.
(a)     2 kW   
(b)     20 kW
(c)     50 kW   
(d)     100 kW
 Ans: d

7.    The load cycle for a motor driving a power press will be   
(a)     variable load
(b)     continuous
(c)    continuous but periodical
(d)    intermittent and variable load
Ans: d

8.    Light duty cranes are used in which of the following ?
(a)     Power houses
(b)     Pumping stations
(c)    Automobile workshops
(d)    All of the above
Ans: d

9.    While selecting an electric motor for a floor mill, which electrical characteristics will be of least significance ?
(a)    Running characteristics
(b)    Starting characteristics
(c)    Efficiency
(d)    Braking
Ans: d

10.   Which of the following motors are pre-ferred for overhead travelling cranes ?
(a)    Slow speed motors
(b)    Continuous duty motors
(c)    Short time rated motors
(d)    None of the above
Ans: c

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Electric Traction Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    Which of the following is an advantage of electric traction over other methods of traction ?
(a)    Faster acceleration
(b)    No pollution problems   
(c)    Better braking action
(d)    All of the above
Ans: a
2.    Which of the following is the voltage for single phase A.C. system ?
(a)    22 V   
(b)    440 V
(c)    5 kV   
(d)    15 kV
(e)    None of the above
Ans: a

3.    Long distance railways use which of the    following ?
(a)    200 V D.C.
(b)    25 kV single phase A.C.    10.
(c)    25 kV two phase A.C.
(d)    25 kV three phase A.C.
Ans: b
4.    The speed of a locomotive is controlled by
(a)     flywheel   
(b)     gear box
(c)    applying brakes    11.
(d)    regulating steam flow to engine
Ans: b

5.    Main traction systems used in India are, those using
(a)    electric locomotives
(b)    diesel engine locomotives
(c)    steam engine locomotives
(d)    diesel electric locomotives
(e)    all of the above
 Ans: e

6, in India diesel locomotives are manu¬factured at
(a) Ajmer   
(b) Varanasi
(c) Bangalore   
(d) Jamalpur
Ans: b

7. For diesel locomotives the range of horsepower is
(a) 50 to 200   
(b) 500 to 1000
(c) 1500 to 2500     
(d) 3000 to 5000
Ans: c

8. _______ locomotive has the highest operational availability.
(a)    Electric   
(b)    Diesel
(c)    Steam
Ans: a

9. The horsepower of steam locomotives is
(a)      upto 1500   
(b)     1500 to 2000
(c)      2000 to 3000     
(d)     3000 to 4000
Ans: a

10. The overall efficiency of steam locomo¬tive is around
(a)    5 to 10 percent
(b)    15 to 20 percent
(c)    25 to 35 percent
(d)    35 to 45 percent
Ans: a

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Control Systems Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    In an open loop control system
(a)    Output is independent of control input
(b)    Output is dependent on control input
(c)    Only system parameters have effect on the control output
(d)    None of the above
Ans: a

2.    For open control system which of the following statements is incorrect ?
(a)     Less expensive
(b)     Recalibration is not required for maintaining the required quality of the output
(c)    Construction is simple and maintenance easy
(d)    Errors are caused by disturbances
Ans: b

3.    A control system in which the control action is somehow dependent on the output is known as
(a)     Closed loop system
(b)     Semiclosed loop system
(c)     Open system
(d)     None of the above
Ans: a

4.    In closed loop control system, with positive value of feedback gain the overall gain of the system will
(a)    decrease   
(b)     increase
(c)     be unaffected    
(d)     any of the above
Ans: a

5.    Which of the following is an open loop control system ?
(a)     Field controlled D.C. motor
(b)    Ward leonard control
(c)    Metadyne   
(d)     Stroboscope
Ans: a

6.    Which of the following statements is not necessarily correct for open control system ?
(a)     Input command is the sole factor responsible for providing the control action
(b)     Presence of non-linearities causes malfunctioning
(c)    Less expensive
(d)    Generally free from problems of non-linearities
Ans: b

7.   In open loop system
(a)    the control action depends on the size of the system
(b)    the control action depends on system variables
(c)    the control action depends on the input signal
(d)    the control action is independent of the output
Ans: d

8    has tendency to oscillate.
(a)    Open loop system
(b)    Closed loop system
(c)    Both (a) and (b)
(d)    Neither (a) nor (b)
Ans: b

9.   A good control system has all the following features except
(a)     good stability   
(b)     slow response
(c)    good accuracy
(d)    sufficient power handling capacity
Ans: b

10.    A car is rtyining at a constant speed of 50 km/h, which of the following is the feedback element for the driver ?
(a)     Clutch   
(b)     Eyes
(c)    Needle of the speedometer
(d)    Steering wheel
(e)    None of the above
Ans: c

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Measurement and Instrumentation Multiple Choice Questions and Answers Preparation for Competition exams pdf

1. The use of _____ instruments is merely confined within laboratories as stand¬ardizing instruments.
(a)     absolute   
(b)     indicating
(c)     recording
(d)     integrating
(e)     none of the above
Ans: a

2. Which of the following instruments indicate the instantaneous value of the electrical quantity being measured at the time at which it is being measured ?
(a)    Absolute instruments
(b)    Indicating instruments
(c)    Recording instruments
(d)    Integrating instruments
Ans: b

3. _____ instruments are those which measure the total quantity of electricity delivered in a particular time.
(a)     Absolute   
(b)     Indicating
(c)     Recording   
(d)     Integrating
Ans: d

4.    Which of the following are integrating instruments ?
(a)     Ammeters   
(b)     Voltmeters
(c)    Wattmeters
(d)    Ampere-hour and watt-hour meters
Ans: d

5.    Resistances can be measured with the help of
(a)     wattmeters      
(b)     voltmeters
(c)    ammeters
(d)    ohmmeters and resistance bridges
(e)    all of the above
Ans: d

6   According to application, instruments are classified as
(a)     switch board    
(b)     portable
(c)     both (a) and (b)
(d)     moving coil
(e)     moving iron     
(f)     both (d) and (e)
Ans: c

7.    Which of the following essential features is possessed by an indicating instrument ?
(a)     Deflecting device
(b)     Controlling device
(c)    Damping device
(d)    All of the above
Ans: d

8.    A _____    device prevents the oscillation of the moving system and enables the latter to reach its final position quickly
(a)     deflecting   
(b)     controlling
(c)     damping   
(d)     any of the above
Ans: c

9.    The spring material used in a spring control device should have the following property.
(a)     Should be non-magnetic
(b)     Most be of low temperature co-efficient
(c)     Should have low specific resistance
(d)     Should not be subjected to fatigue
(e)     All of the above
Ans: e

10.    Which of the following properties a damping oil must possess ?
(a)    Must be a good insulator
(b)    Should be non-evaporating
(c)    Should not have corrosive action upon the metal of the vane
(d)    The viscosity of the oil should not change with the temperature
(e)    All of the above
Ans: e

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Electrical Machine Design Multiple Choice Questions and Answers Preparation for Competition exams pdf

1. Which of the following is the major consideration to evolve a good design ?
(a)     Cost   
(b)     Durability
(c)    Compliance with performance criteria as laid down in specifications
(d)    All of the above
Ans: d
2    impose limitation on design.
(a)    Saturation
(b)    Temperature rise
(c)    Efficiency   
(d)     Power factor
(e)    All above
Ans: e

3.    The efficiency of a machine should be as ______    as possible to reduce the operating cost.
(a)     high   
(b)     low
(c)    either of the above
(d)    none of the above
Ans: a

4.    If an insulating material is operated beyond the maximum allowable temperature, its life is
(a)     drastically increased
(b)     drastically reduced
(c)      unaffected
(d)      none of the above
Ans: b

5.    The design of mechanical parts is particularly important in case of _____ speed machines.
(a)    low   
(b)    medium
(c)    high   
(d)    any of the above
Ans: c

6.    In induction motors, the length of air gap in kept as small as mechanically possible is order to have
(a)     low power factor
(b)     high power factor
(c)    high over load capacity
(d)    any of the above
Ans: b

7.    In ______ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft.
(a)     small   
(b)     medium
(c)     large   
(d)     any of the above.
Ans: c

8.    The length cf air gap to be provided in ______ is primarily determined by power factor consideration.
(a)     d.c. series motor .
(b)     d.c. shunt motor
(c)     induction motor
(d)    synchronous motor
Ans: c

9.   Electrical machines having a power output upto about 750 W may be called_______machines.
(a)    small size   
(b)    medium size
(c)    large size   
(d)    any of the above
Ans: a

10.    Electrical machines having power outputs ranging from a few kW upto approximately 250 kW may be classified as   
(a)     small size machines
(b)     medium size machines
(c)    large size machines
(d)    any ofthe above
Ans: b

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Electrical Engineering Materials Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    The converse of hardness is known as
(a)     malleability     
(b)     toughness
(c)    softness
(d)    none of the above
Ans: c

2.    On which of the following factors does the resistivity of a material depend ?
(a)    Resistance of the conductor
(b)    Area of the conductor section
(c)    Length of the conductor
(d)    All of the above
Ans: d

3.     is a negatively charged particle present in an atom.
(a)     Proton   
(b)     Neutron
(c)    Electron
(d)    None of the above
Ans: c

4.    The formula ____ determines the number of electrons that can be accommodated in any level.
(a)     2n2   
(6)     4n2
(c)     2n3   
(d)     4ns
Ans: a

5.    The tiny block formed by the arrangement of a small group of atoms is called the
(a)     unit cell   
(b)     space lattice
(c)    either (a) or (b)
(d)    none of the above
Ans: a
6.   The co-ordination number of a simple cubic structure is
(a)     2   
(b)     4
(c)     6   
(d)     8
Ans: c

7.   The covalent bond is formed by
(a)     transfer of electrons between atoms
(b)     sharing of electrons between atoms
(e)     sharing of variable number of electrons by a variable number of atoms
(d)     none of the above
 Ans: b

8.    A perfect conductor has
(a)     zero conductivity
(b)     unity conductivity
(c)    infinite conductivity
(d)    none of the above
Ans: c

9.    The metal having the lowest temperature coefficient of resistance is
(a)     gold   
(b)     copper
(c)     aluminium   
(d)     kanthal
Ans: a

10.    Commonly used conducting materials are
(a)     copper   
(b)     aluminium
(c)    both (a) and (b)
(d)    copper and silver
(e)    platinum and gold
Ans: c

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Cables Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    The insulating material for a cable should have
(a)    low cost   
(b)    high dielectric strength
(c)     high mechanical strength
(d)    all of the above
Ans: d

2.    Which of the following protects a cable against mechanical injury ?
(a)     Bedding   
(b)     Sheath
(c)     Armouring   
(d)     None of the above
Ans: c

3.    Which of the following insulation is used in cables ?
(a)    Varnished cambric   
(b)    Rubber   
(c)     Paper
(d)     Any of the above
Ans: d

4.    Empire tape is
(a)    varnished cambric
(b)    vulcanised rubber
(c)     impregnated paper
(d)     none of the above
Ans: a

5. The thickness of the layer of insulation on the conductor, in cables, depends upon
(a)     reactive power
(b)     power factor
(c)    voltage
(d)    current carrying capacity
Ans: c

6. The bedding on a cable consists of
(a)     hessian cloth    
(b)     jute
(c)    any of the above
(d)    none of the above
Ans: c

7. The insulating material for cables should
(a)     be acid proof
(b)     be non-inflammable
(c)    be non-hygroscopic
(d)    have all above properties
Ans: d

8.    In a cable immediately above metallic sheath _____ is provided.
(a)     earthing connection
(b)     bedding   
(c)     armouring
(d)     none of the above
Ans: b

9.    The current carrying capacity of cables in D.C. is more thanthat in A.C. mainly due to
(a)     absence of harmonics
(b)     non-existence of any stability limit
(c)    smaller dielectric loss
(d)    absence of ripples
(e)    none of the above
Ans: c

10.   In case of three core flexible cable the colour of the neutral is
(a)     blue   
(b)     black
(c)    brown
(d)    none of the above
Ans: a

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Switchgear Protections Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    The main function of a fuse is to
(a)     protect the line
(b)     open the circuit
(c)    protect the appliance
(d)    prevent excessive currents
(e)    none of the above
Ans: d

2.    On which of the following routine tests are conducted ?
(a)    Oil circuit breakers
(b)    Air blast circuit breakers
(c)    Minimum oil circuit breakers
(d)    All of the above
Ans: d
3.    SF6 gas
(a)    is yellow in colour
(b)    is lighter than air
(c)    is nontoxic
(d)    has pungent small
(e)    none of the above
Ans: c
 
4. The arcing contacts in a circuit breaker are made of
(a)     copper tungsten alloy
(b)     porcelain
(c)    electrolytic copper
(d)    aluminium alloy
Ans: a

5. Which  of the following  medium is employed for extinction of arc in air circuit breaker ?
(a) Water   
(b) Oil
(c) Air   
(d) SF6
Ans: c

6. With which of the following, a circuit breaker must be equipped for remote operation ?
(a) Inverse time trip
(b) Time-delay trip
(c) Shunt trip   
(d) None of the above
(e) All of the above
Ans: c

7.    Fault diverters are basically
(a) fuses   
(b) relays
(c) fast switches    
(d) circuit breakers
Ans: c

8.    A thermal protection switch can protect against
(a) short-circuit     
(b) temperature
(c) overload   
(d) over voltage
Ans: c

9.    Arc in a circuit behaves as
(a)     a capackive reactance
(b)     an inductive reactance
(c)    a resistance increasing with voltage rise across the arc
(d)    a resistance decreasing with voltage rise across the arc
Ans: d

10.    Thermal circuit breaker has
(a)    delayed trip action
(b)    instantaneous trip action
(c)    both of the above
(d)    none of the above
Ans: a

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Transmission and Distribution Multiple Choice Questions and Answers Preparation for Competition exams pdf

1. By which of the following systems electric power may be transmitted ?
(a)    Overhead system
(b)    Underground system
(c)    Both (a) and (b)
(d)    None of the above
Ans: c

2    are the conductors, which connect the consumer's terminals to the distribution
(a)     Distributors     
(b)     Service mains
(c)    Feeders
(d)    None of the above
Ans: b

3.    The underground system cannot be operated above
(a)     440 V   
(b)     11 kV
(c)     33 kV   
(d)     66 kV
Ans: d
4.    Overhead system can be designed for operation upto
(a)    11 kV   
(b)    33 kV
(c)    66 kV   
(d)    400 kV
Ans: c

5.    If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the
annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement is known as
(a)    Kelvin's law     
(b)    Ohm's law
(c)    Kirchhoffs law
(d)    Faraday's law
(e)    none of the above
Ans: a

6.    The wooden poles well impregnated with creosite oil or any preservative compound have life
(a)    from 2 to 5 years
(b)    10 to 15 years
(c)    25 to 30 years
(d)    60 to 70 years
Ans: c

7.    Which of the following materials is not used for transmission and distribution of electrical power ?
(a)     Copper   
(b)     Aluminium
(c)     Steel   
(d)     Tungsten
Ans: d

8.    Galvanised steel wire is generally used as
(a)     stay wire   
(b)     earth wire
(c)    structural components
(d)    all of the above
Ans: d

9.    The usual spans with R.C.C. poles are
(a)    40—50 metres
(b)    60—100 metres
(c)    80—100 metres
(d)    300—500 metres
Ans: c

10.    The corona is considerably affected by which of the following ?
(a) Size of the conductor
(b) Shape of the conductor
(c) Surface condition of the conductor
(d) All of the above
Ans: d

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Economics of Power Generation Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    Load factor of a power station is defined as
(a) maximum demand/average load
(b) average load x maximum demand
(c) average load/maximum demand
(d) (average load x maximum demand)172
Ans: c

2.    Load factor of a power station is generally
(a) equal to unity  
(b) less than unity
(c) more than unity
(d) equal to zero Diversity factor is always
Ans: b

3.    The load factor of domestic load is usually
(a) 10 to 15%   
(b) 30 to 40%
(c) 50 to 60%   
(d) 60 to 70%
Ans: a

4.    Annual depreciation cost is calculated by
(a)     sinkingfund method
(b)     straight line method
(c)    both (a) and (b)
(d)    none of the above
Ans: c

5.    Depreciation charges are high in case of
(a) thermal plant  
(b) diesel plant
(c) hydroelectric plant
Ans: a
6.    Demand factor is defined as
(a)     average load/maximum load
(b)     maximum demand/connected load
(c)    connected load/maximum demand
(d)    average load x maximum load
Ans: b

7.    High load factor indicates
(a) cost of generation per unit power is increased
(b) total plant capacity is utilised for most of the time
(c) total plant capacity is not properly utilised for most of the time
(d) none of the above
Ans: b

8.    A load curve indicates
(a) average power used during the period
(b) average kWh (kW) energy consumption during the period
(c) either of the above
(d) none of the above
Ans: b

9.    Approximate estimation of power demand can be made by
(a) load survey method
(b) statistical methods
(c) mathematical method
(d) economic parameters
(e) all of the above
Ans: e

10.    Annual depreciation as per straight line method, is calculated by
(a)     the capital cost divided by number of year of life
(b)     the capital cost minus the salvage value, is divided by the number of years of life
(c)    increasing a uniform sum of money per annum at stipulated rate of interest
(d)    none of the above
Ans: b

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Power Plant Engineering Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    The commercial sources of energy are
(a)     solar, wind and biomass
(b)     fossil fuels, hydropower and nuclear energy
(c)    wood, animal wastes and agriculture wastes
(d)    none of the above
Ans: b

2.
(a)    wood, animal wastes and agriculture wastes
(b)    solar, wind and biomass
(c)    either (a) or (b)
(d)    neither (a) or (b)
Ans: a

3.    In India largest thermal power station is located at
(a)    Kota   
(b)    Sarni
(c)    Chandrapur     
(d)    Neyveli
Ans: c

4.    The percentage O2 by Veight in atmospheric air is
(a)    18%   
(b)    23%
(c)    77%   
(d)    79%
Ans: b

5.    The percentage 02 by volume in atmosphere air is
(a)    21%   
(b)    23%
(c)    77%   
(d)    79%
Ans: a

6.    The proper indication of incomplete combustion is
(a)    high CO content in flue gases at exit
(b)    high CO2 content in flue gases at exit
(c)    high temperature of flue gases
(d)    the smoking exhaust from chimney
Ans: a

7.    The main source of production of biogas is
(a)    human waste   
(b)    wet cow dung
(c)    wet livestock waste
(d)    all above
Ans: d

8.    India's first nuclear power plant was installed at
(a)    Tarapore   
(b)    Kota
(c)    Kalpakkam
(d)    none of the above
Ans: a

9.    In fuel cell, the ______ energy is converted into electrical energy.
(a)    mechanical       
(b)    chemical
(c)    heat   
(d)    sound
Ans: b

10.    Solar thermal power generation can be achieved by
(a)    using focusing collector or heliostates
(b)    using flat plate collectors
(c)    using a solar pond
(d)    any of the above system
Ans: d

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Rectifiers and Converters Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    Which of the following are the applications of D.C. system ?
(a)     Battery charging work
(b)     Arc welding 
(c)    Electrolytic and electro-chemical processes
(d)    Arc lamps for search lights
(e)    All of the above
Ans: e

2.    Which of the following methods may be used to convert A.C. system to D.C. ?
(a)     Rectifiers
(b)     Motor converters
(c)    Motor-generator sets
(d)    Rotary converters
(e)    All of the above
Ans: e

3.    In a single phase rotary converter the number of slip rings will be
(a) two   
(b) three
(c) four   
(d) six
(e) none
Ans: a

4.    A synchronous converter can be started
(a)     by means of a small auxiliary motor
(b)     from AC. side as induction motor
(c)    from D.C. side as D.C. motor
(d)    any of the above methods
(e)    none of the above methods
Ans: d

5.    A rotary converter is a single machine with
(a)     one armature and one field
(b)     two armatures and one field
(c)    one armature and two fields
(d)    none of the above
Ans: a

6.    A rotary converter combines the function of
(a)    an induction motor and a D.C. generator
(b)    a synchronous motor and a D.C. generator.
(c)    a D.C. series motor and a D.C. generator
(d)    none of the above
Ans: b

7.    Which of the following is reversible in action ?
(a)    Motor generator set
(b)    Motor converter
(c)    Rotary converter
(d)    Any of the above
(e)    None of the above
Ans: c

8.    Which of the following metals is generally manufactured by electrolysis process ?
(a) Load   
(b) Aluminium
(c) Copper   
(d) Zinc
(e) None of the above
Ans: b

9.    With a motor converter it is possible to obtain D.C. voltage only upto
(a)     200-100 V
(6)     600—800 V
(c)    1000—1200 V
(d)    1700—2000 V
Ans: d

10.    Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required ?
(a)     Motor-generator set
(b)     Motor converter
(c)    Rotary converter
(d)    Mercury arc rectifier
Ans: d

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Synchronous Motors Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    Synchronous motors are generally not self-starting because
(a)    the direction of rotation is not fixed
(b)    the direction of instantaneous torque reverses after half cycle
(c)    startes cannot be used on these machines
(d)    starting winding is not provided on the machines
Ans: b

2.    In case one phase of a three-phase synchronous motor is short-circuited the motor will
(a)     not start
(b)     run at 2/3 of synchronous speed
(c)    run with excessive vibrations
(d)    take less than the rated load
Ans: a

3.    A pony motor is basically a
(a)    small induction motor
(b)    D.C. series motor
(c)    D.C. shunt motor
(d)    double winding A.C./D.C. motor
Ans: a

4.    A synchronous motor can develop synchronous torque
(a)    when under loaded
(b)    while over-excited
(c)    only at synchronous speed
(d)    below or above synchronous speed
Ans: c

5.   A synchronous motor can be started by
(a)    pony motor
(b)    D.C. compound motor
(c)    providing damper winding
(d)    any of the above
Ans: d
6. A three-phase synchronous motor will have
(a) no slip-rings     
(b) one slip-ring
(c) two slip-rings   
(d) three slip-rings
Ans: c

7. Under which of the following conditions hunting of synchronous motor is likely to occur ?
(a)    Periodic variation of load
(b)    Over-excitation
(c)    Over-loading for long periods
(d)    Small and constant load
Ans: a

8.    When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected
(a)    the motor stops
(b)    it runs as a reluctance motor at the same speed
(c)    it runs as a reluctance motor at a lower speed
(d)    none of the above
Ans: a

9.    When V is the applied voltage, then the breakdown torque of a synchronous motor varies as
(a) V   
(b) V312
(c) V2   
(d) 1/V
Ans: a

10.    The power developed by a synchronous motor will be maximum when the load angle is
(a) zero   
(b) 45°
(c) 90°   
(d) 120°
Ans: c

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Single Phase Induction Motors Multiple Choice Questions and Answers Preparation for Competition exams pdf

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
Ans: 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.
Ans: 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
 Ans: 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
Ans: 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°
Ans: 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
Ans: 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
Ans: 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
Ans: 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
Ans: 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
Ans: b

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Polyphase Induction Motors Multiple Choice Questions and Answers Preparation for Competition exams pdf

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

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

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

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

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

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

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

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Transformers Multiple Choice Questions and Answers Preparation for Competition exams pdf

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

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

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D.C Motors Multiple Choice Questions and Answers Preparation for Competition exams pdf

1.    No-load speed of which of the following motor will be highest ?
(a)     Shunt motor    
(b)     Series motor
(c)    Cumulative compound motor
(d)    Differentiate compound motor
Ans: b
2.    The direction of rotation of a D.C. series motor can be changed by
(a)     interchanging supply terminals
(b)     interchanging field terminals
(c)    either of (a) and (b) above
(d)    None of the above
Ans: b

3. Which of the following application requires high starting torque ?
(a) Lathe machine
(b) Centrifugal pump
(c) Locomotive
(d) Air blower
Ans: c

4.    If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?
(a)     Series motor
(b)     Shunt motor
(c)    Differentially compound motor
(d)    Cumulative compound motor
Ans: a

5.    Which D.C. motor will be preferred for machine tools ?
(a)    Series motor
(b)    Shunt motor   
(c)    Cumulative compound motor
(d)    Differential compound motor
Ans: b

6.    Differentially compound D.C. motors can find applications requiring
(a)    high starting torque
(b)    low starting torque
(c)     variable speed
(d)    frequent on-off cycles
Ans: b

7.    Which D.C. motor is preferred for elevators ?
(a)    Shunt motor
(b)    Series motor
(c)    Differential compound motor
(d)    Cumulative compound motor
Ans: d

8.    According to Fleming's left-hand rule, when the forefinger points in the direction of the field or flux, the middle finger will point in the direction of
(a)     current in the conductor aovtaat of conductor
(c)    resultant force on conductor
(d)    none of the above
Ans: a

9.    If the field of a D.C. shunt motor gets opened while motor is running
(a) the speed of motor will be reduced %
(b) the armature current will reduce
(c)  the motor will attain dangerously high speed 1     
(d) the motor will continue to nuvat constant speed
Ans: c

10.    Starters are used with D.C. motors because
(a)    these motors have high starting torque
(b)    these motors are not self-starting
(c)    back e.m.f. of these motors is zero initially
(d)    to restrict armature current as there is no back e.m.f. while starting
Ans: d

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D.C. Generators - Electrical engineering multiple choice questions and answers for competitive exams

1. Laminations of core are generally made of 
(a)     case iron
(b)     carbon
(c) silicon steel
(d) stainless steel

Ans: c

2. Which of the following could be lamina-proximately the thickness of lamina-tions of a D.C. machine ?
(a) 0.005 mm
(b) 0.05 mm
(c) 0.5 m
(d) 5 m

Ans: c

3. The armature of D.C. generator is laminated to 
(a)     reduce the bulk
(b)     provide the bulk
(c) insulate the core
(d) reduce eddy current loss

Ans: d

4. The resistance of armature winding depends on
(a)     length of conductor
(b)     cross-sectional area of the conductor
(c) number of conductors
(d) all of the above

Ans: d

5. The field coils of D.C. generator are usually made of
(a) mica
(b) copper
(c) cast iron
(d) carbon

Ans: b

6. The commutator segments are connected to the armature conductors by means of
(a) copper lugs    
(b) resistance wires
(c) insulation pads
(d) brazing

Ans: a

7. In a commutator
(a)  copper is harder than mica
(b)  mica and copper are equally hard
(c) mica is harder than copper
(d) none of the above

Ans: c

8. In D.C. generators the pole shoes are fastened to the pole core by
(a) rivets
(b) counter sunk screws
(c) brazing
(d) welding

Ans: b

9. According to Fleming's right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of
(a) motion of conductor
(b) lines of force
(c) either of the above
(d) none of the above

Ans: b

10. Fleming's right-hand rule regarding direction of induced e.m.f., correlates
(a) magnetic flux, direction of current flow and resultant force
(b) magnetic flux, direction of motion and the direction of e.m.f. induced
(c) magnetic field strength, induced voltage and current
(d) magnetic flux, direction of force and direction of motion of conductor

Ans: b

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A.C. Fundamentals, Circuits and Circuit Theory - Electrical engineering multiple choice questions and answers for competitive exams

1. A sine wave has a frequency of 50 Hz. Its angular frequency is _______ radian/second.
(a) 100 n
(b) 50 jt
(c) 25 jt
(d) 5 n

Ans: a

2. The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes_____ohms.
(a) 2.5
(b) 5
(c) 10
(d) 15

Ans: c

3. The period of a wave is
(a)    the same as frequency
(6)    time required to complete one cycle
(c) expressed in amperes
(d) none of the above

Ans: b

4. The form factor is the ratio of
(a)    peak value to r.m.s. value
(6)    r.m.s. value to average value
(c) average value to r.m.s. value
(d) none of the above

Ans: b

5. The period of a sine wave is _____ seconds.
Its frequency is
(a) 20 Hz
(b) 30 Hz
(c) 40 Hz
(d) 50 Hz

Ans: d

6. A heater is rated as 230 V, 10 kW, A.C. The value 230 V refers to
(a)  average voltage
(b)  r.m.s. voltage  
(c)     peak voltage
(d)  none of the above
Ans: b

7. If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is
(a) a sinusoid of the same frequency
(b) a sinusoid of half the original frequency
(c) a sinusoid of double the frequency
(d) not a sinusoid
Ans: a

8.   The peak value of a sine wave is 200 V. Its average value is
(a) 127.4 V
(b) 141.4 V
(c) 282.8 V
(d)200V
Ans: a

9. If two sine waves of the same frequency have a phase difference of JT radians, then
(a) both will reach their minimum values at the same instant
(b) both will reach their maximum values at the same instant
(c) when one wave reaches its maximum value, the other will reach its minimum value
(d) none of the above
Ans: c

10. The voltage of domestic supply is 220V. This figure represents
(a) mean value    
(b) r.m.s. value
(c) peak value
(d) average value
Ans: a

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