Deck 20: Electrical Machinery

Question 1

The purpose of the start-capacitor in the capacitor-start motor is ____.

A) to allow the motor to operate as well on DC as it does on AC
B) to save wear and tear on the brushes and commutator
C) to smooth out the 120 Hz vibrations
D) to produce a higher starting torque than that found in the split-phase motor

Answer 1

D

Question 2

On a DC generator, the shunt field is typically labeled ____.

A) S₁ and S₂
C) A₁ and A₂
B) F₁ and F₂
D) T₁ and T₂

Answer 2

B

Question 3

Which of the following is not true of permanent-magnet motors?

A) The main field flux is produced by permanent magnets.
B) An electromagnet is used for the secondary field or armature flux.
C) They has many of the characteristics of a wound rotor induction motor.
D) They consist of permanent magnets mounted on a frame with a rotating armature placed between them.

Answer 3

C

Question 4

Which single-phase AC motor contains a start winding, run winding, and a centrifugal switch?

A) repulsion-start/induction-run
C) split-phase
B) capacitor run
D) universal

Question 5

To change the direction of rotation of a series wound DC generator, the general rule is to ____.

A) reverse the connections to the armature
B) reverse the connections to the field
C) reverse the connections to both the armature and the field
D) this motor cannot be reversed

Question 6

The rotating part of a DC motor that is mounted to the shaft is called ____.

A) field windings
C) armature
B) brushes
D) magnets

Question 7

Which single-phase motor has the highest starting torque?

A) The split-phase motor
C) The capacitor-run motor
B) The capacitor-start motor
D) The universal motor

Question 8

What would be the effect of the loss of load connected to a series wound motor?

A) The motor speed can increase to dangerous levels.
B) The motor will stop rotating.
C) The motor will continue to operate with no adverse effects.
D) The motor will continue to operate but at a reduced speed.

Question 9

On a DC motor, the armature is typically labeled ____.

A) S₁ and S₂
C) A₁ and A₂
B) F₁ and F₂
D) T₁ and T₂

Question 10

The name of the device that provides a surface on which the brush assembly makes electrical contact in DC generator is a(n) ____.

A) armature
C) brush assembly
B) commutator
D) field windings

Question 11

Which of the following statements is true when comparing the series and shunt field windings of a DC motor?

A) The shunt winding must handle more current than the series winding.
B) The shunt winding handles an equal amount of current as the series winding.
C) The series winding handles more current than the shunt winding.
D) The series winding handles less current than the shunt winding.

Question 12

Which of the following is an advantage of the squirrel-cage induction motor over the wound-rotor induction motor?

A) lower cost
C) better speed regulation
B) variable speed
D) smaller size

Question 13

The stationary windings or magnets of a DC motor are called the ____.

A) field windings
C) armature
B) brushes
D) commutator

Question 14

To reverse the direction of rotation of a squirrel-cage motor, you would ____.

A) interchange T₁ and T₂
C) connect T₁ to T₂
B) interchange T₁ and T₃
D) connect T₁ to T₃

Question 15

On a DC motor, the series field is typically labeled ____.

A) S₁ and S₂
C) A₁ and A₂
B) F₁ and F₂
D) T₁ and T₂