250+ TOP MCQs on Stepper Motors and Answers

Control Systems Multiple Choice Questions on “Stepper Motors”.

1. A variable reluctance stepper motor is constructed of ______________ material with salient poles.
A. Paramagnetic
B. Ferromagnetic
C. Diamagnetic
D. Non-magnetic
Answer: B
Clarification: A variable reluctance stepper motor is the motor that has motion in steps with respect to increase in time and constructed of ferromagnetic material with salient poles.

2. In a three-stack 12/8-pole VR motor, the rotor pole pitch is
A. 15º
B. 30º
C. 45º
D. 60º
Answer: C
Clarification: Pole pitch is defined as the number of armature slots to the pole pitch and here this has been converted into degrees.

3. A stepper motor having a resolution of 300 steps/rev and running at 2400 rpm has a pulse rate of- pps.
A. 4000
B. 8000
C. 6000
D. 10,000
Answer: C
Clarification: Pulse per second is mathematically given as PPS = (Rpm/60)*(number of steps per minute).

4. If a hybrid stepper motor has a rotor pitch of 36º and a step angle of 9º, the number of its phases must be
A. 4
B. 2
C. 3
D. 6
Answer: A
Clarification: Step angle is defined as =(N_s-N_r)/(N_s+N_r)*360.

5. The rotor of a stepper motor has no
A. Windings
B. Commutator
C. Brushes
D. All of the mentioned
Answer: D
Clarification: The rotor is the rotatory part of the motor of a stepper motor and has no windings, commutator and brushes.

6. A stepping motor is a ____________ device.
A. Mechanical
B. Electrical
C. Analogue
D. Incremental
Answer: D
Clarification: A stepping motor is a motor in which the motion in the form of steps and is a incremental device i which as the time increases the steps are increased.

7. The rotational speed of a given stepper motor is determined solely by the
A. Shaft load
B. Step pulse frequency
C. Polarity of stator current
D. Magnitude of stator current.
Answer: B
Clarification: The stator part of a motor is the stationary part of the motor and rotational speed of a given stepper motor is given by the step pulse frequency.

8. Which of the following phase switching sequence represents half-step operation of a VR stepper motor ?
A. A, B, C,A……..
B. A, C, B,A…….
C. AB, BC, CA, AB……..
D. A, AB, B, BC……..
Answer: D
Clarification: In the half step operation of a Variable reluctance motor physical step resolution is multiplied by 2 and control signals appear to be digital rather than analog.

9. A stepper motor may be considered as a ____________ converter.
A. Dc to dc
B. Ac to ac
C. Dc to ac
D. Digital-to-analogue
Answer: D
Clarification: A stepper motor is a motor in which the motion is in steps and it is an increemental device and may be considered as a digital to analog converter.

10. What is the step angle of a permanent-magnet stepper motor having 8 stator poles and 4 rotor poles?
A. 60º
B. 45º
C. 30º
D. 15º
Answer: B
Clarification: Step angle is defined as =(Ns-Nr)/(Ns+Nr)*360 where Ns is the number of stator poles and Nr is the number of rotor poles.