Electrical Theory Ii Mod 2

Front 1

When a DC motor started, the initial current is lower than the full load current.

Back 1

False

Front 2

Most large DC machines use wave wound armatures.

Back 2

False frog leg

Front 3

When a generator supplies current to a load counter torque is produced which makes the armature easier to turn.

Back 3

False

Front 4

The terminal voltage of a generator is slightly higher with a load connected, Than no load connected.

Back 4

False

Front 5

DC series motors run at close to a constant speed from a no load to a full load.

Back 5

False

Front 6

Lap wound armatures are used in machines designed for....

Back 6

Low voltage and high current

Front 7

Frog leg wound armatures are used in machines designed for...

Back 7

Moderate current and moderate voltage

Front 8

Interpoles are connected in ______with the______.

Back 8

Series

Armature

Front 9

Provide basic schematic and wiring diagram for a shunt DC motor

Back 9

Draw

Front 10

Provide schematic and wiring diagram for cumulative compound DC motor (long shunt).

Back 10

Draw

Front 11

Provide basic schematic and wiring diagram for DC series motor.

Back 11

DRAW

Front 12

A decrease in load on a DC motor does what?

Back 12

Increase armature speed

Increase cutting action

Increase counter EMF

decreases net voltage

Decrease armature current

Decrease torque

Front 13

Brush armature should be _____ than cummutator segments

Back 13

Softer

Front 14

What DC motors often refer to as a constant speed motor?

Back 14

Shunt

Front 15

Why is the armature core of a DC motor made with steel laminations as opposed to a solid piece of steel?

Back 15

Reduce eddy currents

Front 16

Which kind of d c generators windings are connected in a parallel configuration?

Back 16

Lap wound

Front 17

The conductors on which voltage is induced in a generator or alternator are collectively called the?

Back 17

Armature

Front 18

Which DC machine field winding is made with many turns of smaller gauge wire?

Back 18

Shunt

Front 19

What function does a commutator provide on a DC generator?

Back 19

Mechanical rectifier changing AC to DC

Front 20

If we are providing separate excitation to the rotating electromagnet on a large alternator what must be mounted on the rotor shaft?

Back 20

Two slip rings

Front 21

In a DC generator what term is given to the twisting or bending of the magnetic flux lines between the Pole pieces and what causes this to happen?

Back 21

Armature reaction from magnetic field around armature windings

Front 22

How to calculate net voltage?

Back 22

Volts-counter EMF

Front 23

Inter poles are used to correct________which in turn will help to reduce_________.

Back 23

Armature reaction

Arcing at the brushes

Front 24

In a DC generator what type of compounding results when the shunt in the series fields are connected in a manner whereby they aid in the production of a magnetic field?

Back 24

Cumulative

Front 25

With an increase in speed of a DC motor:

Back 25

cEMF increases

Line current decreases

Front 26

What connections would we be most likely to reverse to change the direction of a DC motor?

Back 26

A1 and A2

Front 27

In a large compound DC motor what is the purpose of the field loss relay?

Back 27

Remove powered motor if shuntfield is lost or current drops below a threshold.

Front 28

Before an automatic transfer switch supplies generator power to a building. What 2 quantities must be close to exact?

Back 28

Voltage

Frequency

Front 29

If we apply full voltage to the armature of the DC motor and reduce voltage is applied to the shuntfield, what will happen to the speed of the motor?

Back 29

Speed increases above base speed

Front 30

What type of DC motor may self-destruct if operated with no connected load?

Back 30

Series

Front 31

Complete diagram for cumulative compound long shunt dc motor with dynamic braking

Back 31

Draw

Front 32

a decrease in load to a DC motor does what to armature rotational speed

Back 32

Increases

Front 33

a decrease in load to a DC motor does what to cutting action?

Back 33

Increases

Front 34

a decrease in load to a DC motor does what to counter EMF?

Back 34

Increases

Front 35

a decrease in load to a DC motor does what to net voltage?

Back 35

Decreases

Front 36

a decrease in load to a DC motor does what to armature current?

Back 36

Decreases

Front 37

a decrease in load to a DC motor does what to torque?

Back 37

Decreases