Quiz 2 Flashcards
In aviation, what are the three general purposes of batteries?
Ground ops, to absorb spikes in voltage from the generator or alternator, emergency back up voltage .
What is a battery?
A device composed of two or more cells on which chemical energy is converted into electrical energy.
Can a primary cell be recharged?
No!
Can a secondary cell be recharged?
Yes!
What are the three different forms of cells?
Dry, wet, gel.
What are the forms of cells based on?
The form of the electrolyte.
What do alkaline batteries consist of?
Lead dioxide, spongy lead, inserted into a solution of sulphuric acid and water.
What kind of cell are alkaline batteries?
Primary ( dry)
What tests are used for determining the condition of lead acid batteries?
Hydrometer test, load test, high rate discharge test.
What does a high discharge test give an indication of?
Capacity
What does a hydrometer test give an indication of?
The stage of charge of the battery .
What does a load test give an indication of?
The state of charge of a battery
What is important to remember when servicing lead acid batteries?
Remove the negative terminal first!
What is a NiCad battery composed of?
Nickel hydroxide, metallic cadmium, inserted into potassium hydroxide and water.
What is the only way to test NiCads?
A high discharge test.
What should be used to neutralize any spilled electrolyte from
NiCad batteries?
Boric acid
What must be remembered when servicing batteries?
Keep NiCads and Lead Acids away from each other.
What must be done when servicing NiCads?
They must be deep cycled to prevent memory and thermal runaway.
What is a generator?
A device that changed mechanical energy into electrical energy.
What is the operation of generators based on?
Electromagnetic induction.
The amount of potential produced by a generator is based on what two things?
Strength of flux field
The rate at which flux is cut
What provides initial excitation?
Initial excitation is provided by lines of flux producing what is called residual magnetism.
What is excitation current?
The current passed through the electromagnet, used to produce, strengthen and control the flux field.
What are the four components of a generator?
Field, armature, brush assembly, structural parts.
What is the purpose of the field?
To provide the lines of flux for the conductor to cut through.
What is the purpose of the armature?
It acts as a conductor which cuts the lines of flux, into which the voltage is induced to produce a “ system” current.
What is the purpose of the brush assembly?
It transfers the system current from the commutator to the housing wiring?
What is the purpose of the structural parts ?
To support the field and armature.
What are the three types of DC generators?
Series wound, shunt wound, compound wound.
What is an advantage associated with series wound gens?
It has higher output capabilities with respect to current and voltage
What is a disadvantage associated with series wound gens?
It is hard to control the output
What is an advantage associated with shunt wound gens?
They are easier to control output?
What is an advantage associated with compound wound generators?
They have a higher current and output voltage capability, and are easier to control.
What is a disadvantage associated with compound wound generators?
They are more complex, and heavier.
What is the output control of a generator based upon?
The current through the field, the speed at which it turns.
What is RCCR?
Reverse current cutout relay!
What is output for AC systems controlled by?
Voltage regulator
Current limiter
Reverse current cutout relay
What is needed to troubleshoot CSD/IDG?
Specific maintenance manual
What is an IDG?
Integrated drive generator
What is a CSD?
Constant speed drive.
What is an APU?
Auxiliary power unit
What is the purpose of a constant speed drive?
To take rotational power from the engine and no matter what the engine speed, turn the generator at a constant speed.
What is the difference between an IDG and a CSD?
An IDG is simply a CSD and a generator combined into one unit.
What is an alternator?
A device which changes mechanical energy into electrical energy by electromagnetic induction.
What is the principle of alternator operation based on?
Electromagnetic induction.
What is the fundamental difference between a generator and an alternator?
The relationship between the conductor and the flux field.
What is the amount of potential produced in an alternator based on?
The strength of the flux field
The rate at which flux are cut
Can alternators produce their own initial excitation?
Nope
What is the purpose of the strator?
It serves the same purpose as the armature in the generator.
What is the purpose of the rotor?
to provide lines of magnetic flux for the conductor to cut through.
What is the purpose of a rectifier?
It is used to convert AC into DC.
What is flux produced by in an alternator?
The rotor, which rotates with 8-12 poles.
What is flux produced by in a generator?
The field, stationary with 2-4 poles.
What is system current produced by in an alternator?
The stator
What is system current produced by in a generator?
The armature (rotating)
What kind if core does an alternator have?
A very small rotating core, so it can spin faster.
What kind of core does a generator have?
A very large rotating core, it is heavier and cannot spin as fast.
What kind of brushes are in an alternator?
Very small brushes
What kind of brushes are used in generators?
Very large brushes
What kind of rectifier is used in an alternator?
Solid state rectifier
What kind of rectifier is used in a generator?
A mechanical rectifier.
What advantages does an alternator have over a generator?
Physical size,
It is capable of greater output
The brushes can be smaller and last longer
