Preview Question paper 1 (121to153)

Q.121 The function of snubber circuit is 
a.)Suppress dv/dt✔
b.)Increase dv/dt
c.)Decrease dv/dt
d.)None of these

Q.122 What is the dielectric of mica?
a.)200
b.)100
c.)3-8✔
d.)1-2

Q.123 What is the name of fluorscent material that give red colour fluorscent
a.)Zinc silicate
b.)Calcium silicate
c.)Zic silphide
d.)Magnesium silicate✔

Q.124 The noise resulting from vibration of lamination set by magnetic force is termed as 
a.) Magneto striction
b.)Boom
c.)Hum✔
d.)Zoom

Q.125 Galvanised steel is generally used as
a.)Stray wire
b.)Earth wire
c.)Structural component
d.)All of the above✔

Q.126 When R2 is rotor resistance , X2 the rotor reactance at supply frequency and s the slip, then the condition for the maximum torque under running codition will be 
a.)sR2=X2
b.)R2=s2X2
c.)R2=s2X22
d.)R2=Sx2✔

Q.127 Which of the following method are suitble for the speed control of squirrel cage induction motor
i.)Voltage contorl
ii.)Frequency control
iii.)Pole changing method
iv.)Rotor resistance control
Select the correct answer using the code given below
a.)2,3 and 4
b.)1,2 and 3✔
c.)1,3 and 4
d.)2 and 4

Q.128 In star delta starting  of an induction motor
a.)Reduce voltage is applied to the rotor
b.)Applied voltage per stator phas is 57.7% of the line voltage✔
c.)Line voltage is 57.7% of stator voltage
d.)resistance is inserted in the rotor

Q.139 Which is following methods of speed control is not affected through stator side
a.)Change of rotor resistance
b.)Change of number of pole
c.)Change of supply voltage
d.)Change of supply frequency✔

Q.130 The wound rotor type induction motor is used for ________speed operation
a.)Constant
b.)Maximum
c.)Minimum
d.)Variable✔

Q.131 Pole changing method is suitable for ______type induction motor
a.)Wound rotor
b.)squirrel cage✔
c.)linear
d.)None of these

Q.132 Buchholz's relay protect from
a.)Winding to winding fault
b.)All type of internal fault✔
c.)Turn to turn fault
d.)None of these

Q.133 A capacity of cranes is expressed in
a.)Span
b.)Type of drive
c.)Tonnes✔
d.)any of the above

Q.134 A saturable core reactor is basically a
a.)Variable resistor
b.)Step down transformer
c.)Thermal relay
d.)Variable impedence✔

Q.135 In case of contactor , overheating of contact is caused from any of the following except
a.)Excess pressure✔
b.)High induction load
c.)Copper oxide on contact
d.)Carrying load for long time

Q.136 In case of low and medium voltage circuit permissible voltage variation is 
a.)1%
b.)5%✔
c.)10%
d.)15%

Q.137 The earth potential is taken as
a.)Infinite
b.)Supply voltage
C.)1Volt
d.)Zero✔

Q.138 MIG welding is 
a.)Mild steel inert gas
b.)Medium inert gas
c.)Mximum inner depth gas welding✔
d.)Matel inert gas

Q.149 For both lap and wave windings, there are a many commutator bars as the number of 
a.)Poles
b.)Slots
c.)Armature conductor
d.)Winding element✔

Q.140 A wir of rsisitance R has its length and cross-section both doubled. Its resistance will become
a.)0.5R
b.)R✔
c.)2R
d.)4R

Q.141 5×1016 electron pass across the section of a conductor in 1 minute and 20 seconds. the current following is
a.) 0.1 mA✔
b.) 1 mA
c.) 10 mA
d.) 100 mA

Q.142 Three element having conductance G1, G2 and G3 are connected in parallel. Their combined conductance will be 
a.) (G1+G2+G3)-1
b.) G1+G2+G3✔
c.)1/G1+1/G2+1/G3
D.)(1/G1+1/G2+1/G3)-1

Q.143 Which of the following has negative temperature coefficient
a.)Electrolytes✔
b.)Brass
c.)Copper
d.)Silver

Q.144 Which of the following has positive temperature coefficient
a.)Germanium
b.)Gold✔
c.)Paper
d.)Rubber

Q.145 The substance used to slow down the speed of neutrons in a nuclear reactor during fission reaction is called
a.)Coolant
b.)Liquid
c.)Moderator✔
d.)Control element

Q.146 Stator core of an induction motor is made of
a.)Laminated cast iron
b.)mild steel
c.)Silicon steel stamping✔
d.)Softwood

Q.147 Slipring of a face wound induction motor are made of
a)Wood
b.)Steel
c.)copper✔
d.)cast iron

Q.148 There is no electrical connection between stator and rotor, still power is transferred from stator to rotor through
a.)Magnetic flux✔
b.)Air
c.)Water
d.)Magnet

Q.149 The plates of lead acid battery is made of 
a.)Rolled zic copper alloy
b.)Perforated nickel-cadmium alloy✔
c.)Cast animonial lead alloy
d.)None of these

Q.150 The lead acit battery , during charging
a.)Anod become whitish in color
b.)Voltage drop
c.)The cell give out energy
d.)Specific gravity of acid increases✔

Q.151 The condition of fully charged lead acid battery can be ascertained by
a.)Specific gravity of electrolyte
b.)Voltage
c.)Gassing
d.)Any of the above✔

Q.152 A circuit that operate in such a way thats output is high when all ita input are high
a.)OR
b.)NAND
c.)NOR
d.)AND✔

Q.153 How many input does a full adder have 
a.) 2
b.) 4
c.) 8
d.) 3✔

Preview Question paper 1 (101-120)

Q.101. A. alternator is supplying a load of 300kW of a power factor of 0.6 lagging . If the power factor is raised to unity , how many kilowatts can alternator supply for the same kVA loading
a.)100kW
b.)200kW✔
c.)300kW
d.)500kW

Q.102. for transmission line which of the following relation is correct  ?
a.)AD-BC=1✔
b.)AC-BD=1
c.)BA-CD=1
d.)BC-AD=1

Q.103. match the following
Types of transmission line types of relay
 preferred
i. Short line               1. Ohm relay
ii. Medium line          2. Reactance relay
iii. Long line.               3. Mho relay
a.) a-1, b-2,c-3
b.)a-2,b-1,c-1✔
c.)a-3, b-2,c-1
d.)a-1,b-1,c-1

Q.104. High Voltage Transmission (HVDC transmission) is mainly used for
a.)Bulk power transmission for very long distance ✔
b.)Interconnecting to system with the same nominal frequency
c.)Eliminating reactive power requirement in the operation
d.)Minimizing harmonics at the converter station

Q.105. Ferranti effect is seen in which transmission line?
a.)Long transmission line ✔
b.)Medium transmission line
c.)short transmission line
d.) Both A and B

Q.106. SCR is a device
a.)Semi-controlled✔
b.)Full-controlled
c.)Uncontrolled
d.)None of these

Q107. For a 3Φ transmission line transmission efficiency of a line decrease with
a.)Increase in load power factor
b.)Decrease in load power factor✔
c.)Does not vary with power factor
d.)Increase in Load current

Q.108. 3Φ synchronous  motor has
a.)High starting torque
b.)Low starting torque
c.)No starting torque✔
d )Low starting current

Q.109. In a synchronous motor
a.)The rotor mmf and stator mmf are stationary with respect to each other ✔
b.)Stator mmf rotates slightly faster then rotor mmf
c.)Rotor mmf rotates slightly faster in comparison to stator mmf
d.)None of these

Q.110. When does a synchronous motor operate with leading power factor electric current?
a.)While it is under excited
b.)While it is over excited✔
c.)While it is critically excited
d.)While it is heavily loaded

Q.111. The use of _____instrument is merely confined within laboratories as standardizing instrument
a.)Indicating
b.)Absolute✔
c.)Recording
d.)Integrating

Q.112. Slip of induction motor is 0.02 and the stator supply frequency is 50Hz . The frequency of rotor induced e.m.f. will be
a.)10Hz
b.)50Hz
c.)1Hz✔
d.)25Hz

Q.113. The watt meter reads 30.34W. The absolute error in the measurement is 2.22W . What is the true value of power
a.)32.56W✔
b.)28.12
c.)25.45
d.)None of these

Q.114.A resistor and an  inductor are connected in series across a voltage source. which two parameter in that circuit decreases if the frequency of source increase
a.)VL and Z
b.)Z and I
c.)VR and I✔
d.)VL and VR

Q.115. Diatance relays operation is depend upon
a.)Ratio of current to current
b.)Ratio of voltage to current✔
c.)Ratio of voltage to voltage
d )Ratio of voltage to resistance

Q.116. Harmonic distortion of signal is produced in RC  coupled amplifier . The probable  cause is
a.)Transistor itself✔
b.)Power supply Vcc
c.)Coupling capacitor Cc
d.)Biasing resistor R1 & R2

Q117. When 't' is thickness of sheet , the top diameter of spot welding is usually
a.) 2t
b.) t
c.) √t✔
d.) 1/t

Q.118. For tramways, the return circuit is through
 a.)Cable
b.)Rails✔
c.)Neutral
d.)Common earthing

Q 119. The rectifier which require the minimum amout of filtering is
a.)Half wave rectifier
b.)Full wave rectifier
c.)Voltage doubler
d.)SCR half wave rectifier✔

Q. 120. A device whose chercterstics are close to ideal voltage source
a.) Diode
b.) FET
C.)Transistor in CB
d.)Zener diode✔

Preview Question paper (1) 81to 100

Q.81. The voltage of super tension cable is up to
a.) 132kV
b.) 66kV
c.) 33kV✔
d.) 220kV

Q.82. Which distribution scheme is employed in metropolitan areas
a.)Radial system
b.)Interconnected system✔
c.)Ring system
d.)None of these

Q.83. A line which connect between substation and distribution transformer
a.)Secondary feeder
b.)Primary feeder✔
c.)Sub transmission feeder
d.)None of these

Q.84. A ratio of average load to maximum load is called.
a.)Plant use factor✔
b.)Diversity factor
c )Load factor
d.)Operation factor

Q.85. In 3Φ Induction motor in order to eliminate cogging the number of stator slot must be
a.)Unequal to number of totor slot and skewed in shape✔
b.)Equal to number of rotor slot
c.)An integral multiple of number of rotor slots
d.)Either B or C

Q.86. A slipring motor run at 290 rpm at full load, when connected to 50Hz supplym Determine the number of pole and slip
a.)P=20, S=3.33%✔
b.)P=40, S=5.79%
c.)P=60, S=0.96%
d.)P=50, S=4.43

Q.87. The rotor of 3Φ induction motor has an impedance of 0.4+j4 ohm per phase at stand still the maximum torque occur at a slip of ______
a.) 10%✔
b.) 15%
c.) 25%
d.) 50%

Q.88. Select the wave that has the least value of form factor
a.)Square wave ✔
b.)Rectangular wave
c.)Triangular wave
d.)Sine wave

Q.89. In a commutation circuit employed to turn off the SCR , satisfactory turn off is obtained when
a.)Circuit turn off time < device turn off time
b.)Circuit turn off time > device turn off time✔
c.)Circuit time constant > device turn off time
d.) Circuit time constant < device turn off time

Q.90. Which of the flowing is true SCR ?
a.)It can block forward voltage and conduct in forward direction
b.)It can block both forward and reverse voltage but conduct in reverse
c.)It can block reverse voltage and conduct in both direction
d.)It can block both forward and reverse voltage but conduct in forward direction✔

Q.91. Holding current is
a.)The minimum current which must pass through the device to remain in th 'ON' stage ✔
b.)Maximum current below which anode current must fall for turning 'ON'
c.)Minimum anode current above which thyristor gets turn 'OFF'
d.)Minimum current below which anode current must fall for turning 'ON'

Q.92. The trapped energy of an inductive load can be feedback to the input supply through a diode known as
a.)Zener diode
b.)Free wheeling diode✔
c.)Power diode
d.)None of these

Q.93. Insulated cable are usually rated by their
a.)Operating Voltage
b.)Operating Voltage and Highest operating temperature✔
c.)Operating temperature
d.)Cost

Q.94.Synchronous machine
a.)Can operate at unity power factor
b.)Can operate at leading power factor
c.)Can operate at lagging  power factor
d.)Can operate at any power factor✔

Q.95. A winding having number of slots equal to number of poles then this winding is called
a.)Concentrated winding✔
b.)Short pitch winding
c.) Full winding
d.)distributed winding

Q.96 Which alternator are more suitable for high speed system
a.)Salient pole
b.) Non salient pole✔
c.)Both A and B
d.)None of these

Q.97.In a Δ connected generator , all of the phase voltage are
a.)Zero
b.)Equal in magnitude✔
c.)One third of total
d.)One sixth of total

Q.98. A ohmmeter is connected across an inductor and the pointer indicate zero ohms .The inductor is
a.)Good
b.)Open
c.)Shorted✔
d.)Partially shorted

Q.99.Moving iron instrument is used
a.)AC and DC both✔
b.)AC only
c.)DC only
d.)None of these

Q 100. For increasing the range of an ammeter, connect
a.)A high voltage resistance in series with the ammeter coil.
b.)A high valur resistance in parallel with the ammeter coil.
c.)A low value resistance in parallel with the ammeter coil.✔
d.)A low value resistance in series with the ammeter coil.

Preview Question paper (1) 41-80

Q.41. The pressure coil of an induction type energy metre is
a.) Highly resistive
b.) Highly inductive✔
c.) Less resistive
d.) Less inductive

Q.42. Beam of electrons in a CRT emanates because of
a.) Secondary emission
b.) Diffusion
c.) Post acceleration
d.) Thermoionic emission✔

Q.43. When conductor are in horizontal formation type of Guard used is are
a.)Cradle Guard✔
b.) Cage guard
c.) Both A and B
d.) Box Guard

Q.44 in cloth washing machine and refrigerator which motor are preferred
a.) DC cumulative compound motor
b.) Slip ring induction motor
c.) Stepper motor
d.) Universal motor✔

Q.45 in DC transmission line
a.) There are no effects due to Inductive and capacitive reactance✔
b.) The effects of Inductive and capacitive reactance are greater than in an AC transmission line of the same rating
c.) It is necessary for the sending end and receiving and to be operated in synchronism
d.) Power transfer capability is limited by stability consideration

Q.46. How many relays are used to detect the inner phase fault
a.) One
b.) Two
c.) Three✔
d.) six

Q.47 the Corona loss on particular system at 50 Hz is 1 kW/km per phase. what is the corona loss at 60Hz in kW/km per phase
a.) 0.83
b.) 1.0
c.) 1.13✔
d.) 1.2

Q.48. A single phase transformer when supplied from 220 V 50Hz Eddy current loss of 50W, if transformer is connected to voltage 430V 50Hz then Eddy current loss will be
a.) 112.50Watt
b.) 191.01Watt✔
c.) 181.56Watt
d.) 205.67Watt

Q.49. Strain insulator is used for voltage level of
a.) >33kV
b.) <11kV✔
c.) >66kV
d.) 132kV

Q.50. Sensitivity factor of a strain gauge is normally of the order of
a.) 1.5-2.0✔
b.) 1-1.5
c.) 0.5-1
d.) 5-10

Q.51. The decimal equivalent of hexadecimal number of2AOF is
a.)17670
b.)17607
c.)10767✔
d.)17068

Q.52.when the magnetic flux and the area under its influence are known, how can one calculate the magnetic flux density
a.)B= Φ×A
b.)B= Φ/A✔
c.)B=A/ Φ
d.) B= Φ×A2

Q.53. the lifting power of an electromagnet can be increased by
a.) Increasing the flux density✔
b.) Decreasing the core area
c.)Decreasing the core length
d.)All of these

Q.54. When the current flow in a conductor, heat is produce because
a.)Heat ∝I2✔
b.)Of electronic collision
c.)Of interatomic collision
d.)Of Joule's Law

Q.55. Conductance is analogous to
a.)Flux
b.)Reluctance
c.)Permeance✔
d.)None of these

Q.56.Transformer is a
a.)Rotating device
b.)Static device✔
c.)Magnetic device
d.)None of these

Q.57. The voltage transformation ratio is
a.)E1/E2
b.)N1/N2
c.)E2/E1✔
d.)None of these

Q.58. Every instant the direction of secondary current in a transformer must be such as to oppose any change in flux. This is in accordance with
a.)faraday's law
b.)Joule's law
c.)Lenz's law✔
d.)Coulomb's law

Q.59. What is the efficiency of transformer compared with that of electrical motor of same rating
a.)Much smaller
b.)Somewhat smaller
c.)About the same
d.)Much higher✔

Q.60.What is typical used of an auto transformer
a.)Isolating transformer
b.)Toy transformer
c.)Control transformer
d.)Variable transformer✔

Q.61. The commercial efficiency of a transformer while a open circuit
a.)Zero✔
b.)Maximum
c.)Either zero or 100%
d.)None of these

Q.62. The special silicon steel is used for lamination because
a.)Eddy current loss are reduced
b.)Hysteresis loss are reduced ✔
c.)Both loss are reduced
d.)None of these

Q.63.Which parameter does not change during transformation action in transformer
a.)Voltage
b.)Frequency✔
c.)Current
d.)None of these

Q.64. An ideal transformer is one which has
a.)No winding resistance
b.)No leakage reactance
c.)No losses
d )All of above✔

Q.65. The input power under no load condition of transformer consist of
a.)Core losses in transformer✔
b.)Core losses and very small amount of copper loss in primary
c.)Copper loss in transformer
d.)Significant copper loss along with negligible core losses

Q.66. In one 132/33kV transformer, the LV resistance is 0.02 per unit . The resistance referred to HV side is 
a.)0.08pu
b.)0.02pu✔
c.)0.16pu
d )0.01pu

Q.67. Lamination of transformer core is made of
a.)Cast iron
b.)Silicon steel✔
c.)Wrought iron
d.)Cast steel

Q.68. Oil is provided in an oil filled transformer
a.)Both cooling and insulation✔
b.)Insulating
c.)Lubrication
d.)Cooling

Q.69. Air core transformer as compared to iron core transformer has
a.)More copper loss
b.)Less magnetic core loss
c.)More magnetic core loss
d.)No magnetic core loss✔

Q.70. CRGO steel is used in the transformer to reduce
a.)Eddy current loss
b.)Ohmic loss
c.)Both eddy current and hysteresis loss
d.)Hysteresis loss✔

Q.71.If input of a ttansformer is square wave the output will be
a.)Pulsed wave✔
b.)Square wave
c.)Triangular wave
d.)Sine wave

Q.72. Two transformer with identical rating are designed with flux densities of 1.2 and 1.4Wb/m2 respectively. The weight of the first transformer per kVA is
a.)Less then that of second transformer
b.)Equal to that of second transformer
c.)More then that of second transformer✔
d.) None of these

Q.73. The flux involved in the emf equation of a transformer has
a.)RMS value
b.)Maximum.value✔
c.)Averge value
d.)Total value

Q.74. The no load current in a transformer lags the applied voltage
a.) 75°✔
b.) 0°
c.) 90°
d.) 115°

Q.75. The leakage flux in a transformer depends upon
a.)The applied voltage
b.)The load current✔
c.)The frequency
d.)The mutual flux

Q.76. For satisfactory parallel operation of two transformer which of the following condition is most essential
a.) Polarities of all transformer operated in parallel must be connected properly ✔
b.) Percentage of impedence of transformer operated in parallel must be same
c.) Voltage ratio of all transformer operated in parallel must be same
d.) MVA rating of all transformer operated in parallel must be same

Q.77. If a transformer has turn ratio K the primary and secondary current I1 and I2 respectively and magnetizing  current and core loss component of no load current Iu and  Iw respectively then
a.) I1=K.I2+Iw
b.) I1=K.I2+Iw+Iu✔
c ) I1=K.I2+Iu
d.  I1=K.I2

Q.78. Which of the follwing  transformer insulating oil generally used in india
a.)Paraffin based insulating oil✔
b.)Naphtha based insulating oil
c.)Aromatic based insulating oik
d.)Olefin based insulating oil

Q 79.Winding conductor of an electrical power transformer are mainly insulated by
a.)Cotton insulating
b.)Rubber insulating
c.)Paper insulating✔
d.)Wooden insulating

Q.80 The charging current in a cable
a.)Lead voltage by 120°
b.)Lag voltage by 90°
c.)Lag voltage by 120°
d.)Lead voltage by 90°✔

Preview Question paper (1) 01-40

Q.1. At what frequency corona loss is more 

a.) 50Hz
b.) 60Hz
c.) 25Hz
d.) 100Hz✔

Q .2.  Insulated cable are usually rated by their
a.) Operating voltage
b.) Operating voltage and highest operating temperature✔
c.) Operating temperature
d.) Cost

Q.3. Class B insulation can bear a temperature ( in degree centigrade) up to
a.)130✔
b.)120
c.)105
d.)90

Q.4. Excess 3 code is known as
a.) Weighted code
b.) Cyclic redundancy code
c.) Self complementing✔
d.) Algebric code

Q.5. To convert a moving coil galvanometer into an ammeter we must connect a
a.) Low resistance in series
b.) High resistance in series
c.) Low resistance in parallel✔
d.) High resistance in parallel

Q.6. Specific resistance of a conductor depend upon
a.) Length of conductor
b.) Nature of conductor material✔
c.) Diameter of conductor
d.) All A B and C

Q.7. A wire length R is half the length of a wire S of similar material.The resistance of R to that S is
a.) 8:1
b.) 1:1
c.) 2:1✔
d.) 4:1

Q.8. The type of slots used in armature of a High Voltage DC motor is
a.) Closed type
b.) Semi closed type✔
c.) Open type with dovetail
d.) Open type with tapered slot

Q.9. m-cells each of emf E are connected in series . The effective emf of combination will be
a.)E
b.)mE✔
c.)E/m
d.)m/E

Q.10. Watt hour is the unit of
a.) Electric power
b.) Electric capacity
c.) Electric energy✔
d.) Electric charge

Q.11. The unit of electrical energy is
a.) Watt-sec
b.)Joule
c.)kWh
d.)All A,B and C✔
Q.12. Atmospheric pressure is measured with a
a.) Hydrometer
b.) Barometer✔
c.) Hygrometer
d.) Altimeter

Q.13. When the speed of a body is doubled its kinetic energy becomes
a.) Double
b.) Half
c.) 4 time✔
d.) 1/4

Q.14. Rocket works on the principle of conservation of
a.) Mass
b.) Energy
c ) Momentum✔
d.) Velocity

Q.15. Bleaching action of chlorine is due to
a.) Reduction
b.) Hydrogenation
c.) Chlorination
d.) Oxidation✔

Q.16. The Solar Eclipse occur when
a.) The sun comes in between the moon and the earth
b.) The earth comes in between the sun and the moon
c.) The moon comes in between the sun and the earth✔
d.) None of the above

Q.17. Material which store energy are classified as
a.) Dielectric material✔
b.) Insulating material
c.) Magnetic material
d.) None of these

Q.18. Variable resistor are
a.) Carbon resistor
b.) Thin film resistor
c.) Nichrome resistor
d.) Wire wound resistor✔

Q.19. The dielectric strength of Transformer oil should be
a.) 5kV
b.) 30kV✔
c.)100kV
d.)132kV

Q.20. Register with negative temperature coefficient are
a.) Ballast resistor
b.) Wire wound resistor
c.) Thermistors✔
d.) None of these

Q.21. In a diode the cut in voltage and forward voltage drop are
a.)0.7,07V
b.)0.7, 1V✔
c.)0.7, 0.6V
d.)1, 0.7V

Q.22. In BJT
a. β= α/ α+1
b.) α= β/ β -1
c.) α= β+1/ β
d.) β= α/ α -1✔

Q.23. The function of a filter in rectifier is to
a.) Limit the total current in the rectifier
b.) Limit the peak voltage of the rectifier
c.) Limit the DC current
d.) Reduce the ripple voltage in the output✔

Q.24. Thyristor can be termed as
a.) DC switch✔
b.) AC switch
c.) Either A or B
d.) Square wave switch

Q.25. An 0-10A ammeter  has a guaranteed accuracy of 1% of full scale deflection the limiting error while reading 2.5 A is
a.)1%
b.)4%✔
c.)2%
d.)none of these

Q.26. Frequency can be measured using
a.) Wein's Bridge✔
b.) Schering Bridge
c.) Heaviside Campbell's Bridge
d.) Maxwell's Bridge

Q.27. A strip Chart recorder is
a.) An active transducer
b.) An inverse transducer
c.) An output transducer
d.) Both B and C✔

Q.28. A photoconductive cell may be called
a.) Photoresistive cells
b.) Photo resistor
c.) Light dependent resistor
d.) All of above ✔

Q.29. In how many different modes a universal shift resistor operate
a.) 2
b.) 3
c.) 4✔
d.) 5

Q.30 In the CMOS inverter the power dessiption is
a.) Low only when Vin is low
b.) Low only when Vin is high
c.) High during dynamic operation
d.) Low during dynamic operation✔

Q. 31. A Boolean algebra F= (A+B) (Ā+C) then
a.) F=AB+ĀC
b.)F= AB+ĀB
c.)F=AC+ĀC✔
d.)F=AA+ĀB

Q.32. The 555 timer has _______ number of modes of operations
a.) 2
b.) 3✔
c.) 4
d.) 5

Q.33. The current drawn by a 220 V DC motor of armature resistance 0.5 Ω and back e.m.f. 200V is
a.) 40A✔
b.) 44A
c.) 400A
d.) 440A

Q.34. Crawling in induction motor is caused by
a.) Improper design of stator lamination
b.) Low voltage supply
c.) High load
d.) Harmonics developed in motor✔

Q.35. A 500 MW, 13.8 kV  star Connect synchronous generator at 0.8 PF will deliver a full load current of
a.) 12.1 kA
b.) 21.0kA
c.)26.15kA✔
d.)46.5kA

Q.36. What is the approximate efficiency of a normal thermal power station
a.)30-40%✔
b.)45-55%
c.)20-25
d.)60-70%

Q.37. Generating station has maximum demand of 30 MW load factor of 60% and plant capacity 50% the reverse capacity of plant is
a.) 5MW
b.) 4MW
c.) 6MW✔
d.) 10MW

Q.38. Bundled conductor are used for EHV transmission this primarily for reducing
a.) Corona loss✔
b.) Surge impedance of line
c.) Voltage drop across line
d.)I2R Losses

Q.39. Which one of the following is to most suitable device for a DC-DC converter
a.)BJT
b.)GTO✔
c.)MOSFET
d.)Thyristor

Q.40. Superposition theorem is not applicable for
a.) Voltage calculation
b.) Bilateral elements
c.) Power calculation✔
d.) passive element

GAS TURBINE

                       Gas Turbine

A gas turbine, also called a combustion turbine , is types of internal combustion engine.
》fresh atmosphere air flow through a compressor that brings in to higher pressure.
》Energy is then added by spraying fuel into the air and igniting it so the combustion generates a high pressure flow .
》Gas turbine are used to power aircraft, train, ships , electrical generator or even tanks.

Kinetic Turbine

Kinetic Turbine

》Kinetic energy turbines, also called free-flow turbines, generator electricity from kinetic energy present in flowing water.

》The systems may operate in river, man-made channels, tidal water, or ocean current.

》 Kinetic systems utilize the water stream's natural path way.

》They do not require the diversion of water through man made channels riverbeds, or pipes.

》They might have applications in such conduits.

》Kinetic systems do not require large civil work; however , they can use existing structure such as bridges , tailraces and channel and do not require any dam or reservoir.

Steam Turbine

                               Steam Turbine

》 A steam turbine is a device that exracts thermal energy frompressurized steam and use it to do mechanical work on rotating output shaft.
》This turbine was invented by Sir Charles Parsons in 1884
》Steam turbines are used for the generation of electricity in thermal power plants, such as plants using coal fuel oil or nuclear fuel.
》Steam turbines are made in a variety of size ranging from small to large . used as mechanical drives for pump , compressor and other shaft driven equipment, used to generate electricity up to 1.5GW.

Applications
》Fuel used are biomass ,coal etc.
》Modern  steam turbine has automatic control system.
》Steam heated process in plant and factories.
》Steam driven turbines in electric power plant.
》Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator bout 90% of all electricity generation in the United State  (1996) 

Kinetic Turbine

                       Kinetic Turbine

》Kinetic energy turbines, also called free-flow turbines, generator electricity from kinetic energy present in flowing water.

》The systems may operate in river, man-made channels, tidal water, or ocean current.

》 Kinetic systems utilize the water stream's natural path way.

》They do not require the diversion of water through man made channels riverbeds, or pipes.

》They might have applications in such conduits.

》Kinetic systems do not require large civil work; however , they can use existing structure such as bridges , tailraces and channel and do not require any dam or reservoir.

Wind Turbine

   

                       

                       Wind turbine

》A turbine is a device that convert kinetic energy from the wind into electrical power.
》Conventional horizontal axis turbine can be divided into three component
a) The rotor component, includes the Blade for converting wind energy to low speed rotational energy.
b) The generatorcomponent, includes the electrical generator the control electronics , and most likely a gearbox
c) The structural support component , includes the tower etc.
》Wind turbine used for charging batteries may be referred to as a wind charger 

Types of Wind turbines

Horizontal axis Wind Turbine :- that turbines are being parallel to the ground, the axis of blade rotation is parallel to the wind flow.

Vertical axis Wind turbines :- Its blades rotating on an axis perpendicular the ground.

Applications

》 Our small wind turbines are used in a variety of industries and applications , including marine application , off grid systems.
》Industrial application including road signage, remote telemetry , mobile base station and for houses , school and farms .

Francis Turbine

Francis Turbine

》The Francis turbine is a type of water turbine that was developed by James B. Franceis and are used for medium head (45-400m) and medium discharge. (10-700m3/s)
》The Francis turbine is a type of reaction turbine, a category of turbine in which the working fluid comes to the turbine under immense pressure and the energy is extracted by the turbine blades from the working fluid .
》the turbine's exit tube is shaped to help deccelerate the water flow and recover the pressure.
》Water flow in radial from exterior to interior .

Applications

》Francis type unit cover a head range from 40-600m (130-2000ft)
》Its efficiency decrease as flow decrease.
》They may be used for pumped storage, where a reservoir is filled by the turbine (acting as a pump) driven by the generator acting as a large electrical motor during period of low power demand .

Crossflow Turbine

Cross flow Turbine 

It is developed by Anthony Michel , in 1903 and is used for low heads (10-70meters) 

》As with water wheel, the water is admitted at the turbine's edge. After passing the runner, it leave on the opposite side .
》Going through the runner twice provides additional efficiency.
》The cross-flow turbine is a low speed machine that is well suited for location with a low a head but high flow.
Applications
》The peak efficeincy af a cross-flow trubine is somewhat less then a kaplon ,francis or pelton tirbine
》It has a low price ,and good regulation.
》As water going through the runner twice ,provide additional efficiency.
》Cross-flow turbine are mostly used in mini and micro hydropower units .
》Its good point as when the water leave the runner, it also help clean the runner of small debris and pollution.

Reaction turbine
》 In a reaction turbine , forces driving the rotor are achieved by the reaction of an accelerating water flow in the runner while the pressure drops. the reaction principle can be observed in a  rotary  lawn sprinkler where the emerging jet drive the rotor in the opposite direction .
》In the reaction turbine torque developed by reacting to the fluids pressure. The pressure of the fluid changes as it passes through the turbine rotor blades.

Types of Reaction Turbines
¤ Kaplan Turbine
¤ Francis Turbine
¤ Kinetic Turbine

》The Kaplan turbine is a water turbine which has adjustable blades and is used for low head and high discharges.
》It was developed in 1913 by the Austrian professor Viktor Kaplan .
》The Kaplan turbine is an inward flow reaction turbine, which means that the working fluid changes pressure as it moves through the turbine and give up its energy .
》The inlet is a scroll-shaped tube that wraps around the turbine's wicket gate. water is directed tangentially through the wicket gate and spiral on to a propeller shaped runner, causing it to spin.
The Kaplan  turbine having drop height 10-700m and flow rate 4-55m3/s

Applications
》 Kaplan turbine are widely used throughout the world for electrical power production . They cover the lowest head hydro sites and are especially suited for high flow conditions
》Inexpensive micro turbines on the kaplan turbine model are manufactured for individual power production with as little as two feet of head.
》Large Kaplan turbine are individually designed for each site to operate at the highest possible efficiency, typically over 90%. They are very expensive to design , manufacture and install, but operate for decades.