Skip to main content

Multiple Choice Interview Questions On Special Motor Part 1

Ques.[1] A variable reluctance stepper motor is constructed of .................. material with salient poles.

(a) paramagnetic
(b) ferromagnetic
(c) diamagnetic
(d) non-magnetic
Answer: B

Ques.[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

Ques.[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

Ques.[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

Ques.[5] The rotor of a stepper motor has no

(a) windings
(b) commutator
(c) brushes
(d) all of the above.
Answer: D

Ques.[6] A stepping motor is a .................. device.

(a) mechanical
(b) electrical
(c) analogue
(d) incremental
Answer: D

Ques.[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

Ques.[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

Ques.[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

Ques.[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

Ques.[11] Wave excitation of a stepper motor results in

(a) microstepping
(b) half-stepping
(c) increased step angle
(d) reduced resolution.
Answer: B

Ques.[12] The torque exerted by the rotor magnetic field of a PM stepping motor with unexcited stator is called ..................torque.

(a) reluctance
(b) detent
(c) holding
(d) either (b) or (c)
Answer: D

Ques.[13] A single-stack, 4-phase, 6-pole VR stepper motor will have a step angle of

(a) 15º
(b) 30º
(c) 45º
(d) 90º
Answer: A
Labels:

Comments

Post a Comment

Comment Policy
We’re eager to see your comment. However, Please Keep in mind that all comments are moderated manually by our human reviewers according to our comment policy, and all the links are nofollow. Using Keywords in the name field area is forbidden. Let’s enjoy a personal and evocative conversation.

Popular posts from this blog

Transformer multiple choice questions part 1

Hello Engineer's Q.[1] A transformer transforms (a) frequency (b) voltage (c) current (d) voltage and current Ans : D Q.[2] Which of the following is not a basic element of a transformer ? (a) core (b) primary winding (c) secondary winding (d) mutual flux. Ans : D Q.[3] In an ideal transformer, (a) windings have no resistance (b) core has no losses (c) core has infinite permeability (d) all of the above. Ans : D Q.[4] The main purpose of using core in a transformer is to (a) decrease iron losses (b) prevent eddy current loss (c) eliminate magnetic hysteresis (d) decrease reluctance of the common magnetic circuit. Ans :D Q.[5] Transformer cores are laminated in order to (a) simplify its construction (b) minimize eddy current loss (c) reduce cost (d) reduce hysteresis loss. Ans : B Q.[6] A transformer having 1000 primary turns is connected to a 250-V a.c. supply. For a secondary voltage of 400 V, the number of secondary turns should be (a) 1600 (b) 250 (c) 400 (d) 1250 A...
4 comments
Read more

Condition for Maximum Power Developed In Synchronous Motor

The value of δ for which the mechanical power developed is maximum can be obtained as, Note : Thus when R a is negligible, θ = 90 o for maximum power developed. The corresponding torque is called pull out torque. 1.1 The Value of Maximum Power Developed        The value of maximum power developed can be obtained by substituting θ = δ in the equation of P m .        When R a is negligible,     θ = 90 o  and cos (θ) = 0 hence, . . .               R a = Z s cosθ   and X s = Z s sinθ        Substituting   cosθ = R a /Z s in equation (6b) we get,         Solving the above quadratic in E b we get,        As E b is completely dependent on excitation, the equation (8) gives the excitation limits for a...
Post a Comment
Read more

Effect of Slip on Rotor Parameters : Part2

Effect of Slip on Rotor Parameters 2. Effect of Slip on Magnitude of Rotor Induced E.M.F        We have seen that when rotor is standstill, s  = 1, relative speed is maximum and maximum e.m.f. gets induced in the rotor. Let this e.m.f. be,                 E 2 = Rotor induced e.m.f. per phase on standstill condition         As rotor gains speed, the relative speed between rotor and rotating magnetic field decreases and hence induced e.m.f. in rotor also decreases as it is proportional to the relative speed N s - N. Let this e.m.f. be,                E 2r = Rotor induced e.m.f. per phase in running condition  Now        E 2r α N s while E 2r α N s - N        Di...
Post a Comment
Read more