1) Which theory explains the mechanism for breakdown under different conditions?
a. Townsend theory
b. Streamer theory
c. Clump theory
d. Only (a) and (b)
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2) Inelastic collisions are those in which internal changes in energy take place within an atom or a molecule at the expenses of total kinetic energy of the colliding particle. Suitable example for inelastic collisions is/are
a. Ionization
b. Attachment
c. Excitation
d. All of these
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3) Druyesteynian distribution applies when the ion energy is much
a. Greater than the thermal energy
b. Lesser than the thermal energy
c. Equal to the thermal energy
d. None of these
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4) A gas in normal state is almost a perfect
a. Conductor
b. Insulator
c. Semi-conductor
d. Dielectric
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5) The Townsend mechanism explains the phenomenon of breakdown
a. Only at low pressure
b. Only at high pressure
c. Only at very high pressure
d. Only bat very low pressure
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6) Liquids dielectrics are mainly used as
a. Impregnants in high voltage cables
b. In capacitors
c. For filling up transformers
d. All of these
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7) For applications in power cables, the dielectrics most commonly used is
a. Polyolefins
b. Mineral oil
c. Benzene
d. Diphenyl
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8) High temperature hydrocarbons have
a. Higher boiling point and low viscosity
b. Lower boiling point and high viscosity
c. Lower boiling point and low viscosity
d. Higher boiling point and high viscosity
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9) Compared to copper and iron losses, dielectric loss in transformer oil is
a. Negligible
b. Equal
c. High
d. Very high
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10) In equipments filled with liquid dielectric, heat is transferred mainly by
a. Conduction
b. Convection
c. Radiation
d. No heat transfers takes place
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11) Which is having higher breakdown strength?
a. Solid dielectrics
b. Liquid dielectrics
c. Gases dielectrics
d. Equal in all
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12) Intrinsic breakdown occurs in time of the order of
a. 10-5 s
b. 105 s
c. 10-8 s
d. 108 s
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13) Within dielectric, an electron starting from the cathode will drift towards the anode and during this motion
a. Gains energy from the field and loses during collision
b. Gains energy during both motion and collision
c. Loses energy during both motion and collision
d. Loses energy from the field and gains during collision
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Answer
Explanation
Related Ques
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ANSWER: Gains energy from the field and loses during collision
Explanation:
No explanation is available for this question!
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14) The thermal breakdown stresses are
a. Lower under ac conditions than under dc condition
b. Greater under ac condition than dc condition
c. Equal in both condition
d. None of these
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Answer
Explanation
Related Ques
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ANSWER: Lower under ac conditions than under dc condition
Explanation:
No explanation is available for this question!
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15) The spreading of spark channels during tracking, in the form of the branches of a tree is called
a. Bunching
b. Treeing
c. sparking
d. none of these
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16) Insulation is necessary for the protection of equipment. Insulation is not necessary between
a. Coils and earth
b. Coils of different phases
c. Turns in a coil
d. None of these
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17) The temperature limit for class F insulation is
a. 105°C
b. 120°C
c. 130°C
d. 155°C
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18) Insulation of dry type transformers is done using prepregs. It is manufactured by using
a. Glass fibres
b. Nomex
c. Aramide papers
d. All of these
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19) SF6 Circuit breakers are manufactured up to the voltage of
a. 33 kV
b. 66kV
c. 480 kV
d. 800 kV
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20) For insulators and bushings of power transformers, circuit breakers and instrument transformers, the suitable materials is
a. Epoxy resin
b. Polyesters resins
c. Porcelain
d. Silicon rubber
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21) In the half wave rectifier, charging current can be limited by using an additional
a. Resistance in series with the secondary of the transformer
b. Inductance in series with the primary of the transformer
c. Inductance in series with the primary of the transformer
d. Capacitance in series with the secondary of the transformer
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Answer
Explanation
Related Ques
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ANSWER: Resistance in series with the secondary of the transformer
Explanation:
No explanation is available for this question!
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22) The ripple voltage for half wave rectifier is
a. Smaller than that of full wave rectifier
b. Larger than that of full wave rectifier
c. Equal to that of full wave rectifier
d. None of these
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23) The voltage doubler circuit is suitable for the voltage up to
a. 2V
b. 4V
c. 6V
d. 8V
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24) A two-pulse circuit requires
a. Double the number of diodes and half of the no. of capacitors required for single-pulse circuits
b. Half of the no. of diodes and double the no. of capacitors required for single-pulse circuits
c. Double the no. of diodes and one and a half times the capacitors required for single-pulse circuits
d. One and a half times the no. of diodes and double the capacitors required for single-pulse circuits
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Answer
Explanation
Related Ques
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ANSWER: Double the no. of diodes and one and a half times the capacitors required for single-pulse circuits
Explanation:
No explanation is available for this question!
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25) In Van de Graaff generators, the shape of high voltage electrode is nearly spherical to avoid
a. High surface field gradients
b. Corona
c. Local discharges
d. All of these
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26) To protect the meter against high voltages in case the series resistance fails, the suitable protective device is
a. Paper gap
b. Neon glow tube
c. Zener diode
d. All of these
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27) A generating voltmeter is a
a. Variable capacitor electrostatic voltage generator
b. Constant capacitor electrostatic voltage generator
c. Variable inductor electrostatic voltage generator
d. Constant inductor electrostatic voltage generator
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Answer
Explanation
Related Ques
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ANSWER: Variable capacitor electrostatic voltage generator
Explanation:
No explanation is available for this question!
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28) The accuracy of the ac field strength depends on
a. Harmonic content
b. Atmospheric conditions
c. Position of meter
d. All of these
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29) For the measurement of ripple voltage in dc systems, the condition to be satisfied is
a. ωCR >> 1
b. ωCR << 1
c. ωCR = 1
d. None of these
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30) Series capacitance voltmeters were used with cascade transformers for measuring rms values up to
a. 100 kV
b. 500 kV
c. 800 kV
d. 1000 kV
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31) The voltage which produces the loss of dielectric strength of insulation is known as
a. Withstand voltage
b. Disruptive discharge voltage
c. Flashover voltage
d. Impulse voltage
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32) The tests which is not performed under power frequency tests is
a. Partial discharge tests
b. Momentary withstand test
c. Visible discharge tests
d. Full wave withstand tests
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33) While performing temperature rise tests, at any part of the bushing the steady temperature rise above the ambient air temperature should not exceed
a. 20 °C
b. 25 °C
c. 35 °C
d. 45 °C
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34) At the instant of contact separation in asymmetrical tests, the dc component is
a. Equal to the ac component
b. Equal to the 50% of ac component
c. Greater than 50% of the ac component
d. Less than the 50% of the ac component
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35) In routine tests, the cable is tested by applying an ac voltage of
a. 2 times the rated value
b. 2.5 times the rated value
c. 3 times the rated value
d. 3.5 times the rated value
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