Defenitions And More

Question 1

Electron flow theory flow from:
-negative to positive
-positive to negative

Answer 1

Negative to positive

Question 2

Do lines of flux flow from:
-north to south poles
- south to north poles

Answer 2

North to south

Question 3

Where are magnetic lines of flux most densely concentrated at?

Answer 3

North and south poles

Question 4

What is electromagnetism?

Answer 4

Current flowing through a conductor creates a magnetic field

Question 5

What are three factors that determine the strength of an electromagnet?

Answer 5

-amount and type of conductor
-magnetic strength of core material
-Amount of current flow

Question 6

What is a materials ability to become magnetized known as?

Answer 6

Permeability

Question 7

What is a materials resistance to become magnetized knows as?

Answer 7

Reluctance

Question 8

What is magnetism left in a material known as?

Answer 8

Residual magnetism

Question 9

What are two types of magnets?

Answer 9

Permanent magnet
Electromagnet

Question 10

What type of DC machine converts, electrical energy to mechanical energy?

Answer 10

Dc Motor

Question 11

What type of DC machine converts, mechanical energy to electrical energy?

Answer 11

DC generator

Question 12

What are six common DC machine components?

Answer 12

Enclosure
Pole pieces
Field windings
Armature assembly
Brushes
Terminals

Question 13

What is the rotating assembly of a DC machine called?

Answer 13

Armature

Question 14

What type of field windings have many terms of small gauge wire?

Answer 14

Shunt field windings

Question 15

What type of field windings have fewer turns of large gauge wire

Answer 15

Series field winding

Question 16

What components of a DC generator converts AC to DC?

Answer 16

Commutator

Question 17

What is the purpose of field windings in a DC machine?

Answer 17

To create magnetic lines of flux

Question 18

What are three basic types of amateur windings?

Answer 18

-Lap wound (low voltage, high current)
-Wave wound (high voltage, low current)
-Frog leg wound (moderate voltage and current)

Question 19

What are two types of bearings?

Answer 19

Sleeve and ball
Roller

Question 20

What keeps the brushes pressed against the commutator?

Answer 20

Brush holder and springs

Question 21

What part of a DC machine supports the shaft and allows it to rotate?

Answer 21

Bearings

Question 22

Why are some pole pieces curved?

Answer 22

To allow for a wider and more even flux distribution

Question 23

What two materials can brushes be made of?

Answer 23

Carbon or graphite

Question 24

What are three types of field windings in DC machines?

Answer 24

-Series
-shunt
-compound

Question 25

What are the shunt field winding terminals labeled?

Answer 25

F1 and F2

Question 26

What are the series field winding terminals labeled?

Answer 26

S1 and S2

Question 27

What is the mechanical force used to turn a generator?

Answer 27

Prime mover

Question 28

What are four components of an armature assembly?

Answer 28

-Shaft -Iron core -commutator -armature windings

Question 29

What separates the sections of copper on a commutator?

Answer 29

Mica insulation

Question 30

What are four types of enclosures?

Answer 30

Open type Weatherproof Drip proof Totally enclosed

Question 31

According to electron theory, does current flow through an energy source from the positive to the negative terminal?

Answer 31

Yes

Question 32

What’s a DC generator that uses permanent magnets as its field known as?

Answer 32

Magneto

Question 33

What is the portion of the pole piece closest to the armature called?

Answer 33

Pole shoe

Question 34

When proper commutation is taking place, what colour is the commutator?

Answer 34

A dark chocolate colour

Question 35

Typically, which three terminal leads are positive in polarity?

Answer 35

A1 S1 F1

Question 36

How can the ripple effect be smooth in the output of a DC generator?

Answer 36

Increasing the number of windings in the armature

Question 37

What are three types of DC machine field structures?

Answer 37

Permanent magnet Separately excited Self excited

Question 38

When a DC generator contains both series and shunt field windings, what is it called?

Answer 38

A compound generator

Question 39

What are three factor factors that determine the output of a generator?

Answer 39

Magnetic field strength Number of conductors in the armature The speed at which the armature is driven

Question 40

When a conductor cuts through magnetic lines of flux, a voltage is induced into the conductor. What is the principal called?

Answer 40

Electromagnetic induction

Question 41

What is the position at which the armature windings are parallel to the lines of flux and there are no induced voltage called?

Answer 41

Neutral plane

Question 42

What two magnetic fields interact to cause the amateur to rotate in a DC motor?

Answer 42

One created by the current in the amateur winding One created by the current in the field windings

Question 43

What is the force that causes a motor to rotate known as?

Answer 43

Lorentz force

Question 44

What are the windings embedded in slots or holes in the main pole faces called?

Answer 44

Compensating windings

Question 45

Is the voltage induced into the armature windings of a DC generator AC or DC?

Answer 45

AC

Question 46

What is the distortion, or bending, of the main magnetic field of a DC machine, caused by its interaction with the magnetic flux developed by the armature current called?

Answer 46

Armature reaction

Question 47

How is the windings of an Interpol connected in relation to the armature?

Answer 47

In series with the armature

Question 48

When a generator supplies current to a load, what is produced, which makes the armature assembly harder to turn?

Answer 48

Counter torque or motion action

Question 49

What happens to counter EMF generated as a load is added to a series motor?

Answer 49

CEMF increases

Question 50

What are three ways armour reaction can be corrected?

Answer 50

Rotate the brushes Interpose and commutating windings Compensating windings

Question 51

True or false The interpose of a DC motor will have the same polarity as the main field poles directly behind them in the direction of rotation ?

Answer 51

True

Question 52

What are two main factors that affect the amount of torque developed in a DC motor?

Answer 52

Strength of the magnetic field Amount of current flow

Question 53

Do series motors have extremely low or extremely high starting to torque?

Answer 53

Extremely high

Question 54

When a conductor cuts through magnetic lines of flux, voltage is induced in the conductor. What is this principal called?

Answer 54

Electromagnetic induction

Question 55

What happens to the torque of DC series motor as the load is increased?

Answer 55

Torque increases

Question 56

What happens to the speed of a DC series motor as a load increases

Answer 56

Speed decreases

Question 57

In a compound generator, there are two different ways in which shunt windings can be connected to the armature series winding. What are they called?

Answer 57

Long shunt Short shunt

Question 58

What type of compound motor has its field windings wound in such a manner that they oppose each other in the production of magnetism?

Answer 58

Differential compound

Question 59

What type of compound motor has its field windings wound in such a manner that they hate each other and production of magnetism?

Answer 59

Cumulative compound

Question 60

What are the three characteristic voltage curves for cumulative compound generators called?

Answer 60

Over compounded Flat compounded Under compounded

Question 61

How is compounding controlled in a compound dc motor or generator?

Answer 61

Series field rheostat

Question 62

What happens to torque of a dc series motor as the load is increased?

Answer 62

Increases

Question 63

If resistance is added to the shunt field winding circuit, what will happen to the magnetic field?

Answer 63

It will decrease

Question 64

If resistance is removed from the shunt field winding circuit of a Dec shunt motor, what will happen to the motor speed?

Answer 64

It slows down

Question 65

What type of devices is used for speed control of a dv shunt motor?

Answer 65

Shunt field rheostat

Question 66

How can the speed of a dc shunt motor be controlled?

Answer 66

By changing the resistance of the shunt field circuit.

Question 67

What is the best way to slow or stop a dc motor under normal operation?

Answer 67

Dynamic braking with mechanical brakes

Question 68

The relationship of the Series and shunt fields in a compound generator determines the amount of _____________ for the machine.

Answer 68

Compounding

Question 69

What type of compounding is used when constant voltage or speed is required?

Answer 69

Flat-compounding

Question 70

How can the output voltage of a dc shunt generator be controlled?

Answer 70

Change the resistance of the shunt field circuit

Question 71

How should the direction of rotation of a dc motor be reversed?

Answer 71

Interchange A1 and A2

Question 72

What protective device connected in series with the shunt field do most large compound motors have?

Answer 72

Field loss relay

Question 73

How is the windings of a interpole connected in relation to the armature?

Answer 73

In series

Question 74

What happens to the speed of a dc series motor as the load is increased?

Answer 74

Speed decreases

Question 75

What type of compounding occurred when a cumulative long-shunt compound motors full-load speed is greater than its no-load speed?

Answer 75

Over compounding

Question 76

What type of compounding occurs when a differential short shunt compound generators full load voltage is less than no load voltage?

Answer 76

Under compounding

Question 77

What is the function of the shunt field rheostat?

Answer 77

Voltage control for generators and speed control motors

Question 78

What is the function of the series rheostat

Answer 78

To control the amount of compounding

Question 79

A motor can be operated as a generator when the motor needs to be slowed or stopped quickly. What is this type of DC motor control called?

Answer 79

Dynamic breaking

Question 80

Is resistance and voltage directly or inversely proportional in a DC shunt generator?

Answer 80

Inversely proportional

Question 81

Is resistance and speed directly or inversely proportional in a DC shunt motor?

Answer 81

Directly proportional

Question 82

What type of armature windings provide high voltage and low current?

Answer 82

Wave wound

Question 83

What type of generator is considered a constant voltage generator?

Answer 83

Shunt generator or flat compounded

Question 84

In a compound motor, there are two ways in which a shunt winding can be connected to the armature and series windings. What are they called?

Answer 84

Long shunt Short shunt

Question 85

If the current through the shunt field of a large compound motor decreases below a certain level, what protective device disconnects power to the armature?

Answer 85

Field loss relay

Question 86

Does an increase in current flow in a conductor result in an increase of magnetic field around the conductor?

Answer 86

Yes

Question 87

What causes the shift of the neutral plane on a DC motor under load?

Answer 87

Armature reaction

Question 88

If resistance is added to the shunt field, winding circuit of a DC generator, what will happen to the output voltage?

Answer 88

It will decrease

Question 89

If resistance is added to the shunt field, winding circuit of a DC generator, what will happen to the output voltage?

Answer 89

It will decrease