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°✔