Powerplant Systems & Components: Engine Electrical Systems 🔊

Question 1

How would you seat newly installed generator brushes to the commutator?

Answer 1

When new brushes are in a generator the faces must be shaped to provide maximum contact with commutator. To seat brushes, wrap sandpaper around the commutator, turn the armature in the normal direction of rotation until the face of the brushes is properly contoured. Remove the sandpaper and blow out any residue with compressed air.

Question 2

When is it necessary to replace the brushes in a starter?

Answer 2

Once they are half their original length

Question 3

Where is the generator rating and performance data located?

Answer 3

On the data plate attached to the generator

Question 4

What units make up a DC generator three-unit regulator?

Answer 4

The voltage regulator, current limiter, and reverse current cutout

Question 5

What method is used to control the voltage of an aircraft alternator?

Answer 5

The voltage regulator

Question 6

What determines the frequency of the voltage of an alternator?

Answer 6

It depends upon the speed of rotation of the rotor and the number of poles

Question 7

How is alternator frequency maintained?

Answer 7

Installing a constant speed drive (CSD) unit between the engine and alternator

Question 8

What are the three basic types of DC motors?

Answer 8

Series motors, shunt motors, and compound motors

Question 9

Name the parts of a DC motor.

Answer 9

The armature, brushes, commutator, and field frame (ABC-F)

Question 10

Why is the starter-generator system use on many turbine engines?

Answer 10

To save space and weight

Question 11

Why should stranded wire be used in powerplant applications?

Answer 11

It is less likely to fatigue and break from vibrations

Question 12

What is the American Wire Gauge (AWG) system of designating electrical wire size?

Answer 12

Gauge is assigned according to its cross-sectional area, the smaller the number the larger the wire

Question 13

What is opening wiring? (not an open circuit)

Answer 13

Any wire, wire group, or wire bundle not enclosed in conduit

Question 14

What methods are used to control the voltage output of a DC aircraft generator?

Answer 14

Vibrating type voltage regulator, three-unit regulator, and carbon-pile

Question 15

What aircraft electrical system normally does not have a fuse or circuit breaker?

Answer 15

Starter circuit

Question 16

Why are protective covers placed on some electrical switches?

Answer 16

To prevent the switch from accidentally being actuated

Question 17

What are the causes of excessive arcing at the generator brushes?

Answer 17

Arcing can be caused by a commutator that is dirty, rough, or out of round. A common cause of arcing is worn or binding brushes or when brush spring tension is too low.

Question 18

When installing single wires or wire bundles, how much slack is normally allowed between supports?

Answer 18

Slack between supports should normally not exceed .5”

Question 19

What precaution should be taken when running wires close to heating ducts or exhaust stacks?

Answer 19

The wires should be insulated with a high temperature resistant material

Question 20

What is indicated on the amp meter when the engine is running and the AC generator is producing power?

Answer 20

That power is being produced