Hi friends, this is post about objectives of electrical engineering with emphasis on dc motor check out and comment...
1) In a dc motor if the brushes are given a back shift, then
A) commutation is improved
B) commutation is worsened
C) speed increases
D) speed decreases
E) speed remains unaffected
F) both (A) and (C)
Ans:F
2) In comparison to shunt and compound motors, a dc series motor develops high torque at start. It is due to its comparatively
A) few series turns
B) stronger series field
C) larger armature current
D) smaller armature resistance
Ans:B
3) In a dc motor, the shaft torque is less than armature torque. This is due to
A) eddy current loss
B) hysteresis loss
C) stray loss
D) all of the above
Ans:C
4) For smaller values of armature current Ia, the torque developed by a dc series motor is proportional to
A) Ia
B) Ia^2
C) √Ia
D) 1/Ia
Ans:B
5) For higher values of armature current Ia, the torque developed by a dc series motor is proportional to
A) Ia
B) Ia^2
C) √Ia
D) 1/Ia
Ans:A
6) The dc motor, which can provide zero speed regulation at full load without any controller is
A) series
B) shunt
C) cumulatively compound
D) differential compound
Ans:B
7) A series motor drawing an armature current of Ia is operating under saturated magnetic conditions. The torque developed in the motor is proportional to
A) 1/Ia
B) 1/Ia^2
C) Ia^2
D) Ia
Ans:D
8) If N is the speed of a dc series motor and Ia is the armature current then
A) N∝(1/Ia)
B) N∝Ia
C) N∝Ia^2
D) N∝(1/Ia^2)
Ans:A
9) For higher values of armature current, the speed of a dc series motor is
A) proportional to armature current
B) proportional to the square of armature current
C) inversely proportional to armature current
D) constant
Ans:D
10) A 240 V dc series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 Ω. The value of resistance which must be added to obtain rated torque at 1000 rpm is
A) 6 Ω
B) 5.7 Ω
C) 2.2 Ω
D) 1.9 Ω
Ans:D
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1) In a dc motor if the brushes are given a back shift, then
A) commutation is improved
B) commutation is worsened
C) speed increases
D) speed decreases
E) speed remains unaffected
F) both (A) and (C)
Ans:F
2) In comparison to shunt and compound motors, a dc series motor develops high torque at start. It is due to its comparatively
A) few series turns
B) stronger series field
C) larger armature current
D) smaller armature resistance
Ans:B
3) In a dc motor, the shaft torque is less than armature torque. This is due to
A) eddy current loss
B) hysteresis loss
C) stray loss
D) all of the above
Ans:C
4) For smaller values of armature current Ia, the torque developed by a dc series motor is proportional to
A) Ia
B) Ia^2
C) √Ia
D) 1/Ia
Ans:B
5) For higher values of armature current Ia, the torque developed by a dc series motor is proportional to
A) Ia
B) Ia^2
C) √Ia
D) 1/Ia
Ans:A
6) The dc motor, which can provide zero speed regulation at full load without any controller is
A) series
B) shunt
C) cumulatively compound
D) differential compound
Ans:B
7) A series motor drawing an armature current of Ia is operating under saturated magnetic conditions. The torque developed in the motor is proportional to
A) 1/Ia
B) 1/Ia^2
C) Ia^2
D) Ia
Ans:D
8) If N is the speed of a dc series motor and Ia is the armature current then
A) N∝(1/Ia)
B) N∝Ia
C) N∝Ia^2
D) N∝(1/Ia^2)
Ans:A
9) For higher values of armature current, the speed of a dc series motor is
A) proportional to armature current
B) proportional to the square of armature current
C) inversely proportional to armature current
D) constant
Ans:D
10) A 240 V dc series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 Ω. The value of resistance which must be added to obtain rated torque at 1000 rpm is
A) 6 Ω
B) 5.7 Ω
C) 2.2 Ω
D) 1.9 Ω
Ans:D
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