Engine electrical systems Flashcards
When the engine is operating, what does an ammeter/load meter indicate when connected to: battery positive lead, and/or the generator output lead?
Battery positive lead- the ammeter indicates whether the battery is charging or discharging
Generator output lead - indicates the current produced by the generator or electrical system load
What is done to ensure that each generator shares the load in a multiple generator system?
The generators are paralleled
Where would you find generator rating and performance data?
On generator data plate
How is the voltage of a DC generator controlled?
Varying the current
What is the most common type of alternator used in most aircraft AC systems?
Three phase alternator
How does a voltage regulator control the voltage of an alternator?
By regulating the voltage output of the DC exciter
What does the speed of rotation and number of poles in an alternator determine?
The frequency of the alternator output
What are some methods used to maintain 400 HZ alternator output frequency on large turbo jet or turbo fan engines?
CSD
IDG
Variable speed constant frequency system (VSCF)
Name the major parts of a DC motor
Armature
Field brushes
Frame assembly
Name the components of a direct cranking electrical starter system
Electric motor
Reduction gears
Automatic, engaging and disengaging mechanism
Name three types of DC motors
Series
Shunt (parallel)
Compound
What type of DC motor is commonly used for a reciprocating engine starter and why?
A series wound motor because it has a high starting torque under heavy load conditions
What are the operating modes of a turbine engine starter generator?
As a starter and then as a generator once the engine is running
What is a possible indication for when a starter drags?
A noisy, dirty and/or worn commutator
Where would wires with high temperature installation material be used?
When they run close to high temperature areas like exhaust stacks, or heating ducts
What is the size standard for electrical wire used in US manufactured aircraft?
American wire gauge (AWG)
How are wire sizes represented?
Buy a number measured by a gauge. Smaller wires are represented by larger numbers. The smallest wire size normally used an aircraft is a 22 gauge.
What is the maximum slack allowed between the supports of a single wire or a bundle installation?
1/2 inch
Why are wires bonded on power plant installations?
To provide a current return path for electrical accessories, and to prevent static discharge
What DC alternator system component prevents battery reverse current flow into the armature?
The rectifier
