Engine Electrical Systems

Question 1

When the engine is operating what does an ammeter/load meter indicate when connected to:
1– battery positive lead
2 – generator output lead

Answer 1

Battery positive lead – the armature indicates whether the batteries are charging or discharging
Generator output lead – indicates the current produced by the generator or electrical system load

Question 2

What is done to ensure that each generator shares the load in a multiple generator system?

Answer 2

The generators are paralleled

Question 3

Where would you find generator rating in performance data?

Answer 3

On the generator data plate

Question 4

How is the voltage of a DC generator controlled?

Answer 4

Varying the current

Question 5

What is the most common type of alternator use the most aircraft AC systems?

Answer 5

The three phase alternator

Question 6

How does a voltage regulator control the voltage of an alternator?

Answer 6

Buy regulating the voltage output of the DC exciter

Question 7

What does the speed of rotation and number of poles of an alternator determine?

Answer 7

The frequency of the alternator output

Question 8

What are some methods used to maintain 400 Hz alternator output frequency on a large turbo jet or turbo fan engines?

Answer 8

Constant Speed Drive (CSD), Integrated Drive Generator (IDG) and Variable Speed Constant Frequency (VSCF) power systems

Question 9

Name the major parts of a DC motor

Answer 9

The armature, field brushes and frame assembly

Question 10

Name the components of a direct cranking electrical starter system

Answer 10

An electric motor, reduction gears and an automatic engaging and disengaging mechanism

Question 11

Name three types of DC motors

Answer 11

Series, shunt (parallel) and compound

Question 12

What type of DC motor is commonly use for reciprocating engine starter and why?

Answer 12

A series wound motor – it has a high starting torque under heavy load conditions

Question 13

What are the operating modes of a turbine engine starter generator?

Answer 13

First as a starter, then as a generator once the engine is running

Question 14

What is a possible indication when a starter drags?

Answer 14

A noisy, dirty, worn starter commutator

Question 15

Where would wire with high temperature insulation material be used?

Answer 15

When they run close to high temperature areas - such as exhaust stacks or heating ducts

Question 16

What is the standard size for electrical wire used in US manufactured aircraft

Answer 16

The American wire gauge AWG

Question 17

How are wire sizes represented?

Answer 17

By numbered gauge size, the smaller wires are represented by large numbers. The smallest wire normally used in aircraft is 22 gauge.

Question 18

What is the maximum slack allowed between the supports of a single wire or bundle installation?

Answer 18

1/2 inch

Question 19

Why are wires bonded on power plant installations?

Answer 19

To provide a current return path for electrical accessories and to prevent static discharge

Question 20

What DC alternator system component prevents battery reverse current flow into the armature?

Answer 20

The rectifier