DC Motors

Question 1

T or F:
Direct current does not change direction and always moves in the same direction?

Answer 1

True

Question 2

What determines the direction of flow in a DC motor?

Answer 2

The polarity of the source

Question 3

T or F:
DC motors are more complex and costly than AC motors?

Answer 3

True

Question 4

What are the 2 basic types of DC motors?

Answer 4

1) Brushed
2) Brushless

Question 5

Name the 2 categories of DC brush type motors:

Answer 5

1) Permanent magnet
2) Field wound

Question 6

Which type of DC motors use permanent magnets as the stator?

Answer 6

Permanent magnet motor

Question 7

The magnetic field that permanent magnet motors create are _____ and _____.

Answer 7

Fixed and constant

Question 8

What is the rotating portion of a DC motor called?

Answer 8

Armature

Question 9

What part of a DC motor has windings that are attached to a segmented copper cylinder?

Answer 9

Commutator

Question 10

What is the typical HP range available for permanent magnet motors?

Answer 10

1/4 - 5HP

Question 11

What are the 3 types of field wound DC motors:

Answer 11

1) Series
2) Shunt
3) Compound

Question 12

Which 2 Field wound DC motors should require a lockout in 2 different places?

Answer 12

1) Shunt
2) Compound

Question 13

When the magnetic field for brushed type DC motors is produced by wire-wound poles on the stator, this is called?

Answer 13

Field wound

Question 14

What type of motor has field windings connected in series with the armature windings?

Answer 14

Series wound

Question 15

What DC motor type has field windings that are generally connected in shunt or parallel with the armature?

Answer 15

Shunt wound

Question 16

Which field wound DC motor has high starting torque, but can over speed when unloaded?

Answer 16

Series wound

Question 17

Which field wound DC motor does not over speed when lightly loaded, but may run away upon loss of shunt field power?

Answer 17

Shunt-wound

Question 18

Which field wound DC motor has both shunt and series windings?

Answer 18

Compound motor

Question 19

Which field wound DC motor has both great torque and speed control?

Answer 19

Compound shunt

Question 20

Which type of DC motor has the magnets mounted on the rotor and the windings are in the stator?

Answer 20

Brushless motor

Question 21

Which type of DC motor has neither a commutator nor brushes?

Answer 21

Brushless motor

Question 22

T or F:
Brushless DC motors deliver more torque at higher speeds than conventional permanent magnet motors?

Answer 22

True

Question 23

General purpose brushless DC motors are widely available with ratings up to about _____ HP at _____ RPM’s.

Answer 23

20
1800

Question 24

What is used to turn AC to DC?

Answer 24

Rectifier

Question 25

What is used to turn DC to AC?

Answer 25

Inverter

Question 26

What is used to turn high voltage AC into lower AC voltage?

Answer 26

Transformer

Question 27

Name 5 types of DC motors:

Answer 27

1) Permanent magnet 2) Series 3) Shunt 4) Compound-shunt 5) Brushless