Motors Final Review pt 1/4

Question 1

The ability of a material to conduct magnetic flux is called ____.

Answer 1

Permeability

Question 2

The ability of a material to retain residual magnetism is called ____.

Answer 2

Permeance

Question 3

With a DC motor, a ____ is used to reverse the current direction, therefore, keeping the current flowing in on direction (DC) through the windings to keep the polarity correct in order to interact with the main fields.

Answer 3

Commutator

Question 4

Mutual Inductance is the ability of an inductor in one circuit to ____ a voltage in another circuit or conductor.

Answer 4

Induce

Question 5

Similar to an AC motor, a _____ is the fixed part of an alternator that supplies a magnetic field though the field windings.

Answer 5

Stator

Question 6

A DC ____ operates on the principle that voltage is induced in a coil of wire when the coil is rotated in a magnetic field.

Answer 6

Generator

Question 7

The three factors that control the output of an alternator are :

Answer 7

1. length of the wire2. speed of the rotor3. strength of the magnetic field

Question 8

The ____ output of an alternator or generator must be between +5% & -10% of the requirements for the load(s).

Answer 8

voltage

Question 9

If the total number of coils wound in a three phase stator is 36, then each phase contains ____ coils.

Answer 9

12

Question 10

The ____ us a cylindrical bar used to carry the revolving rotor and transfer power from the motor to the load.

Answer 10

Motor shaft

Question 11

The synchronous speed of a 60-Hz, 4 pole motor is ____ .

Answer 11

1,800 RPM120 x 60 / 4; 120 x Hz / P (# of poles)

Question 12

____ torque is also referred to as breakaway torque or starting torque.

Answer 12

Locked Rotor

Question 13

Motor power is rated in ____ or ____.

Answer 13

Horsepower / watts

Question 14

____ is calculated by dividing output power by input power.

Answer 14

Motor efficiency

Question 15

____ and ____ are used to connect the rotor of a wound-rotor motor to an external set of secondary resistors.

Answer 15

Brushes & slip rings

Question 16

When the speed of a motor changes, the horsepower and torque required at the new speed may be ____.

Answer 16

Higher/Lower/The same

Question 17

The construction of the ____ in a wound rotor motor is identical to that of the ____ motor.

Answer 17

Stator / squirrel cage

Question 18

The rotor is mounted on a ____ that is used to transfer power to the load.

Answer 18

shaft

Question 19

Three phase AC power is generated by rotating coils through the ____.

Answer 19

Magnetic field

Question 20

The rotor’s magnetic field and the stator’s magnetic field interact to create ____.

Answer 20

torque

Question 21

The ____ is the stationary part of an AC motor. It consists of a laminated iron core and windings that convert electrical energy to the energy of a magnetic field.

Answer 21

Stator

Question 22

The speed of a wound rotor motor may be reduced by increasing the ____ of the rotor circuit while the motor is running, in order to reduce the current in the rotor windings.

Answer 22

resistance

Question 23

The windings of a 3-phase wound rotor motor are located ____ electrical degrees apart in the slots of the stator.

Answer 23

120360 / # of phases

Question 24

The rotor winding coils of a wound rotor motor are made up of ____.

Answer 24

insulated copper conductors.

Question 25

When troubleshooting a three phase motor, the motor windings should be checked for any opens or shorts by using a DMM (digital multi-meter) set to measure ____.

Answer 25

resistance