MCQs on Electrical Actuating Systems – Stepper Motors
1 - Question
Which type of device is a stepper motor?
a) Electromechanical
b) Electrochemical
c) Embedded system
d) Electromagnetic
View Answer
Explanation: A stepper motor is an electromagnetic device which converts the electrical pulses into discrete mechanical movements. The shaft of the electrical motor.
2 - Question
The speed of the rotation of the stepper motor depends on ____
a) torque
b) number of input pulses
c) frequency of input pulses
d) solenoid
View Answer
Explanation: The speed of rotation of input pulses is directly related to the frequency of input pulses. In the other options, the motor has full torque at standstill. The length of rotation is directly proportional to the number of input pulses applied. Solenoids are used as electrical actuators.
3 - Question
Stepper motors are extremely reliable.
a) True
b) False
View Answer
Explanation: There are no contact brushes in the motor, therefore, the Stepper motors are extremely reliable. The life of the motor depends only upon the life of the bearings. Wide ranges of rotational speed are possible. advertisement
4 - Question
Length of rotation is directly related to to ____
a) torque
b) number of input pulses
c) frequency of input pulses
d) solenoid
View Answer
Explanation: The length of rotation is directly proportional to the number of input pulses applied. In the other options, the speed of rotation of input pulses is directly related to the frequency of input pulses, the motor has full torque at standstill. Solenoids are used as electrical actuators.
5 - Question
Which among the following is not the type of a stepper motor?
a) Variable reluctance
b) Permanent magnet
c) Hybrid
d) Variable magnet
View Answer
Explanation: Variable magnet is not the type of a stepper motor. Variable reluctance stepper motor consists of a soft iron multi-toothed rotor and a wound stator. Permanent magnet stepper motors have a rotor made up of the permanent magnet. Hybrid stepper motor provides better performance with respect to step resolution, torque and speed.
6 - Question
A stepper motor is a bad choice whenever control movement is required.
a) True
b) False
View Answer
Explanation: A stepper motor is a good choice whenever control movement is required. They can be used in the applications where there is a need to control rotation angle, speed, position and synchronism. Due to all these reasons, stepper motors are used in many different applications.
7 - Question
A soft iron multi-toothed rotor and wound stator is present in _______
a) permanent magnet stepper motor
b) variable reluctance stepper motor
c) hybrid stepper motor
d) DC motor
View Answer
Explanation: Variable reluctance stepper motor consists of a soft iron multi-toothed rotor and a wound stator. When the stator windings are energized with DC current, the poles become magnetized, and the teeth of the rotor are attracted towards the energized stator poles, and hence the rotor rotates. The other motors present in the options do not consist of such elements.
8 - Question
Which type of stepper motors have low cost and low-resolution motor?
a) Permanent magnet stepper motor
b) Variable reluctance stepper motor
c) Hybrid stepper motor
d) DC motor
View Answer
Explanation: The permanent magnet stepper motor has low cost and low-resolution type motor with the step angle of 7.5% to 15%. This type of stepper motor has a rotor made up of the permanent magnet. The other motors mentioned in the option do not have low cost as well as low redundancy.
9 - Question
Which among the following is a property of hybrid stepper motor?
a) Contains a soft iron multi-toothed rotor
b) Low cost and low-resolution motor
c) The better performance provided with respect to step resolution
d) Provides an increased magnetic flux
View Answer
Explanation: A hybrid stepper motor provides better performance with respect to step resolution, torque and speed, and this is more expensive than the other two stepper motors. This motor has advantages of both variable reluctance and permanent magnet stepper motors. The other functions mentioned in the options are the functions of other types of the stepper motor.
10 - Question
Which of the following is not the main selection criterion of a stepper motor?
a) Resolution required
b) Drive mechanism component required
c) Torque required
d) Speed
View Answer
Explanation: Speed is not the main selection criteria of a stepper motor. The selection criteria of a stepper motor include resolution required, drive mechanism component, operating pattern required such as sequencing, accelerationetc. and torque required.
11 - Question
What is the formula to calculate the step angle of a stepper motor?
a) (360*ph.)/nph
b) (ph/nph)
c) (nph/ph)
d) (360*nph)/ph
View Answer
Explanation: The step angle is given by (360*ph)/nph where ‘nph’ is the number of equivalent poles per phase or number of rotor poles, ‘ ph ‘ is the number of phases and ‘ n ‘ is the total number of poles in all phases.
12 - Question
What is the step angle of a hybrid stepper motor?
a) 0.9 degree to 3.6 degree
b) 0.9 degree to 7.0 degree
c) 0.1 degree to 1.0 degree
d) 1.0 degree to 0.9 degree
View Answer
Explanation: Typical step angle of a hybrid stepper motor ranges from 0.9 degrees 3.6 degree that is (100 to 400) steps per revolution. The step angle is given by (360*ph)/nph where ‘nph’ is the number of equivalent poles per phase or number of rotor poles, ‘ ph ‘ is the number of phases and ‘ n ‘ is the total number of poles in all phases.