mod 5

Question 1

are electrical components that convert mechanical energy into electrical energy by electromagnetic induction. It supplies the needed electrical energy for the operation of most electrical equipment on aircrafts.

Answer 1

GENERATORS

Question 2

might be supplied by a waterfall, steam, wind, gasoline or diesel engine, or an electric motor.

Answer 2

THE MECHANICAL ENERGY

Question 3

Also known as dynamo, it is an electrical generator that creates direct current, converts the alternating current to a direct current, using a commutator; it allows the current flow in one direction only.

Answer 3

DC GENERATOR

Question 4

Also known as alternators, it is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. In an alternator, the electrical current periodically reverses its direction.

Answer 4

AC GENERATOR

Question 5

In 1831, he demonstrated that this, in fact, could be accomplished. This discovery is the basis for the operation of the generator.

Answer 5

MICHAEL FARADAY (an english scientist)

Question 6

One end of a single armature coil attaches to one commutator segment, while the other end is soldered to the adjacent segment.

Answer 6

LAP WINDING

Question 7

In a _____ lap winding, the ends of each coil are connected to adjacent commutator segments. In this way all the coils are connected in series.

Answer 7

SIMPLEX

Question 8

In a _____ lap winding, there are in effect two separate sets of coils, each set connected in series. The two sets of coils are connected to each other only by the brushes.

Answer 8

DUPLEX

Question 9

A _____ lap winding is in effect three separate sets of series-connected coils.

Answer 9

TRIPLEX

Question 10

In a _____, the ends of each coil are connected to commutator segments two pole spans apart. Instead of short-circuiting a single coil, a brush will short-circuit a small group of coils in series.

Answer 10

WAVE WINDING

Question 11

The generator’s field coils are energized or excited from an independent external dc source, such as a battery.

Answer 11

SEPARATELY EXCITED

Question 12

When a generator supplies its own excitation; field coils are energized from the current produced by the generator itself.

Answer 12

SELF-EXCITED

Question 13

Where the field winding in series with armature winding.

Answer 13

SERIES-WOUND

Question 14

Where the field winding in parallel with armature winding.

Answer 14

SHUNT-WOUND

Question 15

Combination of series and shunt winding. It is used more extensively than other types of generators because it can be designed so that it has a wide variety of characteristics.

Answer 15

COMPOUND-WOUND

Question 16

When the shunt field is in parallel only with the armature.

Answer 16

SHORT-SHUNT

Question 17

When the shunt field is in parallel with both the armature and series field.

Answer 17

LONG-SHUNT

Question 18

consist of copper losses in the electric circuits and mechanical losses due to the rotation of the machine.

Answer 18

THE LOSSES OF GENERATORS AND MOTORS

Question 19

Used to carry the field winding and poles. It is a hollow cylinder and together with the rotor constitutes the magnetic circuit or core of the machine.

Answer 19

STATOR

Question 20

Used to carry the armature winding. It is cylindrical in shape. The armature is the load carrying member.

Answer 20

ROTOR

Question 21

Used as a load carrying member mounted on the rotor. This winding rotates in the magnetic field set up at the stationary winding (Field winding). An _____ is a continuous winding; that is, it has no beginning or end. It is composed of a number of coils in series.

Answer 21

ARMATURE WINDING

Question 22

An exciting system which may be an electrical winding or a permanent magnet and which is located on the stator.

Answer 22

FIELD WINDING

Question 23

Rotates with the rotor and serves to rectify the induced voltage and the current in the armature, both of which are alternating current. The coils on the armature are terminated and interconnected through the _____ which comprises a number of bars or _____ segments which are insulated from each other.

Answer 23

COMMUTATOR

Question 24

Conducting carbon graphite spring loaded to ride on the commutator and act as interface between the external circuit and the armature winding.

Answer 24

BRUSHES

Question 25

Provided to place field winding. The number of ______ is determined by the voltage and current ratings of the machine.

Answer 25

POLES

Question 26

A magnetic material used for mechanical support, protection from abrasion, and further electrical insulation. Also, it is used to avoid non-conducting _____ liners wedged between the coils and the _____ walls.

Answer 26

SLOT/TEETH

Question 27

Provided to support the iron core, the brushes and the bearings.

Answer 27

MOTOR HOUSING

Question 28

is the starting twist or force that produces rotation in a motor. This rotation is necessary to get motors started.

Answer 28

TORQUE

Question 29

Necessary to produce its rated horsepower (hp) at full-load speed.

Answer 29

FULL-LOAD TORQUE

Question 30

Required to bring the motor up to rated speed.

Answer 30

PULL-UP TORQUE

Question 31

Maximum torque the motor will develop with rated voltage applied at rated frequency without an abrupt drop in speed.

Answer 31

BREAKDOWN TORQUE

Question 32

Developed when full power is applied when the rotor is stationary; the starting torque or twist that gets the rotor running. _____ is by far the most common type of torque considered by electric installers when wiring electric motors.

Answer 32

LOCKED-ROTOR TORQUE

Question 33

This is the most common type of dc motor. It is connected in the same way as the shunt generator. Its characteristic speed-load and torque-load curves show that the torque increases linearly with an increase in armature current, while the speed drops slightly as the armature current is increased.

Answer 33

SHUNT MOTOR

Question 34

The field of this type of motor is connected in series with the armature. The speed varies from a very high speed at light load to a lower speed at full load. The _____ is suitable for starting with heavy, connected loads (driving cranes and winches) because at high armature currents, it develops a high torque and operates at low speed.

Answer 34

SERIES MOTOR

Question 35

It combines the operating characteristics of the shunt and series motors. The _____ may be operated safely at no load. As load is added, its speed decreases, and torque is greater compared with that of a shunt motor

Answer 35

COMPOUND MOTOR

Question 36

is designated by the number of revolutions of the shaft with respect to time and is expressed in units of revolutions per minute (rpm).

Answer 36

SPEED