Explore topic-wise MCQs in Design Electrical Machines.

This section includes 19 Mcqs, each offering curated multiple-choice questions to sharpen your Design Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.

1.

For good performance the small dc motor should have magnetic to electrical boarding ratio greater than 70.

A. true
B. false
Answer» C.
Discussion
2.

What is the formula of the magnetic to electrical boarding ratio?

A. magnetic to electrical boarding ratio = number of poles * permeance coefficient * flux per pole/number of conductors * armature current
B. magnetic to electrical boarding ratio = number of poles / permeance coefficient * flux per pole*number of conductors * armature current
C. magnetic to electrical boarding ratio = number of poles + permeance coefficient * flux per pole/number of conductors * armature current
D. magnetic to electrical boarding ratio = number of poles * permeance coefficient / flux per pole*number of conductors * armature current
Answer» B. magnetic to electrical boarding ratio = number of poles / permeance coefficient * flux per pole*number of conductors * armature current
Discussion
3.

What is the value of the reluctance factor in the calculation of the intensity of magnetic field?

A. 1
B. 2
C. 1.15
D. 1,45
Answer» D. 1,45
Discussion
4.

What is the value of the demagnetizing coefficient if the total number of teeth is greater than 107?

A. d = angle/360
B. d = angle/240
C. d = angle/540
D. d = angle/720
Answer» E.
Discussion
5.

The field current flowing in the conductor’s acts as demagnetizing force on the fraction tips of the magnet.

A. true
B. false
Answer» C.
Discussion
6.

WHAT_IS_THE_VALUE_OF_THE_DEMAGNETIZING_COEFFICIENT_IF_THE_TOTAL_NUMBER_OF_TEETH_IS_GREATER_THAN_107??$

A. d = angle/360
B. d = angle/240
C. d = angle/540
D. d = angle/720
Answer» E.
Discussion
7.

What is the formula of the magnetic to electrical boarding ratio?$

A. magnetic to electrical boarding ratio = number of poles * permeance coefficient * flux per pole/number of conductors * armature current
B. magnetic to electrical boarding ratio = number of poles / permeance coefficient * flux per pole*number of conductors * armature current
C. magnetic to electrical boarding ratio = number of poles + permeance coefficient * flux per pole/number of conductors * armature current
D. magnetic to electrical boarding ratio = number of poles * permeance coefficient / flux per pole*number of conductors * armature current
Answer» B. magnetic to electrical boarding ratio = number of poles / permeance coefficient * flux per pole*number of conductors * armature current
Discussion
8.

What_is_the_value_of_the_reluctance_factor_in_the_calculation_of_the_intensity_of_magnetic_field?$

A. 1
B. 2
C. 1.15
D. 1,45
Answer» D. 1,45
Discussion
9.

What is the formula for the flux density for the PM motors?

A. flux density = residual flux density / 1 + (1.11/permeance coefficient)
B. flux density = residual flux density * 1 + (1.11/permeance coefficient)
C. flux density = residual flux density / 1 + (1.11*permeance coefficient)
D. flux density = residual flux density * 1 + (1.11*permeance coefficient)
Answer» B. flux density = residual flux density * 1 + (1.11/permeance coefficient)
Discussion
10.

For good performance the small dc motor should have magnetic to electrical boarding ratio greater than 70?

A. true
B. false
Answer» C.
Discussion
11.

How is the value of the magnetic to electrical boarding ratio related with the volume of iron and volume of copper?

A. high magnetic to electrical boarding ratio gives high copper volume and high iron volume
B. high magnetic to electrical boarding ratio gives low copper volume and high iron volume
C. low magnetic to electrical boarding ratio gives low copper volume and low iron volume
D. low magnetic to electrical boarding ratio gives low copper volume and high iron volume
Answer» C. low magnetic to electrical boarding ratio gives low copper volume and low iron volume
Discussion
12.

The field current flowing in the conductor’s acts as demagnetizing force on the fraction tips of the magnet?#

A. true
B. false
Answer» C.
Discussion
13.

What is the usual value of the permeance coefficient of the PMDC motor?

A. 4
B. 5
C. 6
D. 7
Answer» D. 7
Discussion
14.

What is the range of the permeance coefficient in the PMDC motors?

A. 3-5
B. 4-9
C. 4-8
D. 3-9
Answer» D. 3-9
Discussion
15.

What factor does the permeance coefficient depend upon?

A. geometry of the magnet
B. geometry of the magnet, airgap, associated non-portions of the magnetic circuit
C. airgap
D. associated non-portions of the magnetic circuit
Answer» C. airgap
Discussion
16.

What happens to the diameter when the poles are more than 2?

A. diameter = 2 * diameter * (number of armature teeth embraced by one coil/total number of armature teeth)
B. diameter = 2.32 * diameter * (number of armature teeth embraced by one coil/total number of armature teeth)
C. diameter = 2.32 * diameter * (number of armature teeth embraced by one coil * total number of armature teeth)
D. diameter = 2 * diameter / (number of armature teeth embraced by one coil/total number of armature teeth)
Answer» C. diameter = 2.32 * diameter * (number of armature teeth embraced by one coil * total number of armature teeth)
Discussion
17.

What is the formula for the armature resistance in PMDC motor?

A. armature resistance = (Diameter + length)*total number of armature conductors/1.2 * 104 * number of parallel paths in the armature2
B. armature resistance = (Diameter + length)*total number of armature conductors*1.2 * 104 * number of parallel paths in the armature2
C. armature resistance = (Diameter + length)*total number of armature conductors/1.2 * 104 + number of parallel paths in the armature2
D. armature resistance = (Diameter + length)+total number of armature conductors/1.2 * 104 * number of parallel paths in the armature2
Answer» B. armature resistance = (Diameter + length)*total number of armature conductors*1.2 * 104 * number of parallel paths in the armature2
Discussion
18.

What is the range of the copper factor in PMDC motors?

A. 0.1-0.3
B. 0.1-0.2
C. 0.1-0.4
D. 0.2-0.4
Answer» C. 0.1-0.4
Discussion
19.

What does the copper factor in PMDC motors represent?

A. it represents the armature circular area for conductors
B. it represents the field circular area for conductors
C. it represents the fraction of the armature circular area for conductors
D. it represents the fraction of the field circular area for conductors
Answer» D. it represents the fraction of the field circular area for conductors
Discussion