1) If the armature current of dc series motor has become twice then the torque will become
a. Twice of the former
b. Four times of the former
c. One fourth of the former
d. Remains same
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Answer
Explanation
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ANSWER: Four times of the former
Explanation:
No explanation is available for this question!
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2) For low reluctance path for the flux in armature, the permeability of the material should be
a. High
b. Low
c. Both (a) and (b)
d. None of these
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Answer
Explanation
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ANSWER: Low
Explanation:
No explanation is available for this question!
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3) In a d.c. machine, the form of armature reaction mmf is
a. Triangular
b. Sinusoidal
c. Saw tooth
d. Rectangular
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Answer
Explanation
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ANSWER: Triangular
Explanation:
No explanation is available for this question!
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4) A 120 V shunt generator running at 850 rpm has its armature and shunt field resistance of 0.15 ohm and 50 ohm respectively. It supplies 200 lamps each rated at 60 W, 100 V. The friction and windage and core loss of the machine is 400 W. its armature copper loss on full load and shunt field loss is
a. 2156.7 W, 200 W
b. 2232.6 W, 200 W
c. 2156.7 W, 240 W
d. 2232.6 W, 240 W
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Answer
Explanation
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ANSWER: 2232.6 W, 200 W
Explanation:
No explanation is available for this question!
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5) If A is the number of parallel paths and P is the number of poles, then the number of parallel path in lap winding and in wave winding is
a. A = P, A = 2
b. A = 2P, A = P
c. A = 2, A = P
d. A = P, A = 2P
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Answer
Explanation
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ANSWER: A = P, A = 2
Explanation:
No explanation is available for this question!
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6) If % ηm is the mechanical efficiency of a DC machine and % ηe is the electrical efficiency. Then the overall efficiency of DC machine is given by
a. % η m + % η e
b. % η m X % η e
c. (% η m + % η e) / % η m
d. (% η m + % η e) / % η e
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Answer
Explanation
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ANSWER: % η m X % η e
Explanation:
No explanation is available for this question!
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7) In a self excited generator, if the series field opposes the shunt field, then the generator is
a. Cumulatively compounded
b. Differentially compounded
c. Series generator
d. None of these
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Answer
Explanation
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ANSWER: Differentially compounded
Explanation:
No explanation is available for this question!
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8) Laminations or stampings are used to reduce the eddy current losses. The direction of laminations should be such that
a. They are perpendicular to the paths of eddy current and flux both
b. They are parallel to the paths of eddy current and flux both
c. They are perpendicular to the paths of eddy current and parallel to the flux
d. They are parallel to the path of eddy current and perpendicular to the flux
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Answer
Explanation
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ANSWER: They are perpendicular to the paths of eddy current and parallel to the flux
Explanation:
No explanation is available for this question!
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9) With the increase in temperature, the speed of series and shunt motor will
a. Increase, decrease
b. Decrease, increase
c. Increase, increase
d. Decrease, decrease
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Answer
Explanation
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ANSWER: Decrease, increase
Explanation:
No explanation is available for this question!
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10) If Eb is the back emf of d.c. motor and V is the terminal voltage, then the condition for maximum power is
a. E b = V
b. E b = 2V
c. E b = ( V / 2 )
d. E b = V ∧ 2
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Answer
Explanation
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ANSWER: Eb = ( V / 2 )
Explanation:
No explanation is available for this question!
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