Practice Test: Question Set - 10
1. Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
- (A) Series motor
- (B) Shunt motor
- (C) Cumulatively compounded motor
- (D) Differentially compounded motor
2. Which D.C. motor is generally preferred for cranes and hoists?
- (A) Series motor
- (B) Shunt motor
- (C) Cumulatively compounded motor
- (D) Differentially compounded motor
3. For a D.C. shunt motor if the excitation is changed
- (A) Torque will remain constant
- (B) Torque will change but power will remain
constant
- (C) Torque and power both will change
- (D) Torque, power and speed, all will change
4. The hysteresis loss in a D.C. machine least depends on
- (A) Frequency of magnetic reversals
- (B) Maximum value of flux density
- (C) Volume and grade of iron
- (D) Rate of flow of ventilating air
5. D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the
- (A) Series motor
- (B) Shunt motor
- (C) Compound motor
- (D) Any of the above
6. If the field of a D.C. shunt motor gets opened while motor is running
- (A) The speed of motor will be reduced %
- (B) The armature current will reduce
- (C) The motor will attain dangerously high speed
1
- (D) The motor will continue to run at constant
speed
7. The ratio of starting torque to full-load torque is least in case of
- (A) Series motors
- (B) Shunt motors
- (C) Compound motors
- (D) None of the above
8. For which of the following applications a D.C. motor is preferred over an A.C. motor?
- (A) Low speed operation
- (B) High speed operation
- (C) Variable speed operation
- (D) Fixed speed operation
9. The armature voltage control of D.C. motor provides
- (A) Constant voltage drive
- (B) Constant current drive
- (C) Constant torque drive
- (D) None of the above
10. The condition for maximum efficiency for a D.C. generator is
- (A) Eddy current losses = stray losses
- (B) Hysteresis losses = eddy current losses
- (C) Copper losses = 0
- (D) Variable losses = constant losses
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