Question is ⇒ In D.C. machines the residual magnetism is of the order of, Options are ⇒ (A) 2 to 3 per cent, (B) 10 to 15 per cent -, (C) 20 to 25 per cent, (D) 50 to 75 per cent, (E) , Leave your comments or Download question paper.

Question is ⇒ In D.C. machines the residual magnetism is of the order of, Options are ⇒ (A) 2 to 3 per cent, (B) 10 to 15 per cent -, (C) 20 to 25 per cent, (D) 50 to 75 per cent, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	In D.C. machines the residual magnetism is of the order of
A.	2 to 3 per cent [Correct Answer]
B.	10 to 15 per cent - [Wrong Answer]
C.	20 to 25 per cent [Wrong Answer]
D.	50 to 75 per cent [Wrong Answer]
View Answer 3 -2 Explanation:- Answer : A Discuss it below : !! OOPS Login [Click here] is required to post your answer/result Help other students, write article, leave your comments

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⇒ Which of the following motors have almost constant speed over their full load range ?
A.C. series motors
D.C. series motors
D.C. shunt motors
Low resistance squirrel cage motors

⇒ At the instant of starting when a D.C. motor is put on supply, it behaves like
a highly resistive circuit
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⇒ Between Field's test and Hopkinson's test the main common thing is that both
use negligible power
are regenerative tests
need two similar mechanicallycoupled motors
need two electrically coupled series motors

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Swinburne's test
Hopkinson's test
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⇒ Which of the following motors one will choose to drive the rotary compressor ?
D.C. shunt motor
D.C. series motor
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a weaker commutating field is needed at low speed than at higt speed
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⇒ A shearing machine has cyclic load consisting of intermittent light and henry loads. Which of the following D.C. motor will be suitable for this purpose?
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starting torque of the motor
efficiency of the motor
speed regulation of the motor

⇒ Torque developed by a D.C. motor depends upon
active length of the conductor
current flow through the conductors
number of conductors
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hysteresis loss
field copper loss
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⇒ If a D.C. motor is connected across the A.C. supply it will
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⇒ If the field of a D.C. shunt motor gets opened while motor is running
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the motor will attain dangerously high speed
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⇒ A series motor is started without load. The effect is that
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⇒ Which of the following tests can be conducted on all types of D.C. machines ?
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⇒ A D.C. series motor, as compared to shunt and compound motors, has the highest torque at the start because of its comparatively
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lower armature resistance
large armature current
fewer series turns

⇒ The series parallel system of speed control of D.C. series motors widely used in traction work gives a speed range of about
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1 : 8
1 : 6
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⇒ D.C. generators are installed near the load centres to reduce
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sparking
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