Electrical System Flashcards
Electrical current measurement
Amps
Amps measures…?
Electrical current
What is electrical current?
Rate of flow of electric charge
Rate of flow of electric charge is known as?
Current
What is needed to make a current flow through a component?
Potential difference (voltage)
Voltage is also known as..?
Potential difference
What current comes from a battery or generator?
DC
What converts DC to AC?
Inverter
What does an inverter do?
Converts DC to AC
What type of current flows only in one direction?
DC
Voltage measures what?
The force driving electricity through a circuit
What is the reciprocal of resistance?
Conductivity
What is the reciprocal of conductivity?
Resistance
Ohm’s Law
V = IR
What symbol represents current?
I
The symbol I represents what?
Current
An AC current changes its flow at regular intervals known as?
Cycles
What is a complete cycle of an AC current?
Current flowing to a maximum and minimum point then back to 0
What is frequency?
Rate at which AC changes direction
What does Hertz essentially mean?
Cycles per second
Measurement of frequency is?
Hertz
Cycles per second is known as?
Hertz
What changes AC to DC?
Rectifier
What does a Rectifier do?
Changes AC to DC
What voltage is easier to produce? AC or DC?
AC
What is amplitude?
Maximum value of a wave relative to zero
What is the maximum value of a wave relative to zero known as?
Amplitude
What is a Phase?
Position in the waveform relative to 360 degrees
In teerms of phases, how many degrees is one complete cycle of a wave?
360
Frequency and wavelength relationship type?
Inverse
Frequency and wavelength relationship?
Higher frequency = Shorter wavelength
What symbol represents one wavelength?
Lambda
An electric current passing through a coppeer wire does what?
Generates a magnetic field
What is the electrical system typically in a light aircraft?
DC
What must be done to electricity generated by an aircraft’s alternator?
It must be rectified into DC
What connects a batteery/alternator and an aircraft’s various electrical components?
Bus bar
If a Bus bar is Earthed, what does that mean for an aircraft’s electrical components?
They are also Earthed
What is Common Earth?
Thee notion that aa Bus Bar’s components are Earthed due to the Bus Bar being Earthed
What is the ‘exhaust’ of a typical battery?
Hydrogen and oxygen
The ‘exhaust’ of hydrogen and oxygen from a charging battery means what for its storage?
It must be vented
When is the largest current draw on the battery?
Start-up
For batteries in series, what is added together?
Voltage
How are battery voltages added together?
In series
For batteries in parallel, what is added together?
Capacity
How are battery capacities added together?
In parallel
Aircraft batteries are typically arranged in what system?
Parallel
What remains constant for batteries in parallel?
Voltage
What changes for batteries in parallel?
Amps
Where must battery fluid be in relation to its plates?
The fluid should coveer the plates
How is electricity generated in a generator?
Moving a wire armature within a magnetic field
The output of a compound wound generator is relatively…?
Constant
How is a generator electrically self-sufficient?
It has its own permanent magnetic field
Why is an alternator not electrically self-sufficient?
It doesn’t have a permanent magnetic field
What current does a generator produce?
AC
Principles of an alternator?
Magnetic field spins within a wire
What characterises the wires of an alternator (known as the stator)?
They are stationary
What is a stator?
Stationary set of wires in an alternator
What rectifies AC in an alternator?
Diodes
What do diodes do in an alternator?
Rectify AC into DC
How do diodes rectify in an alternator?
They only permit one direction of flow
What is the secondary operation of a diode in an alternator?
Preventing reverse current flow from the battery into the alternator
What controls the flow of current in an alternator?
Diode
What is the relationship between an alternator’s voltage and battery voltage?
The alternator voltage is marginally higher than the battery voltage
Why is the alternator voltage marginally higher than the battery voltage?
To allow the battery to be fully recharged
What system characteristic allows an aircraft battery to be fully recharged?
Alternator voltage is higher than the battery voltage
What are thee main advantages of an alternator?
Provides constant electrical output
Lighter than generators
Easier to maintain
What is the principle disadvantage of an alternator?
It requires an initial current to create a magnetic field
Significant issue with an alternator’s setup of a magnetic field spinning within a wire?
The magnetic field requires a battery
Current out of a battery is known as?
Discharge
What is discharge?
Current out of a battery
Solenoids are used in what electrical device?
Relay
How is a typical relay contact held open (meaning the circuit is incomplete)?
By a spring
What is often the cause of an excessive current?
Faulty voltage regulator
What component prevents excessive currents?
Voltage regulator
What type of material prevents electrostatic charge from dissipating easily?
Insulator
What type of material allows electrostatic charge to dissipate easily?
Conductor
A continuous conducting path on an aircraft is essential to preventing what?
Differential electrical charge between parts that can produce sparks
What is necessary to prevent differential electrical charge between parts that can produce sparks?
Continuous conducting path
What components ensure conducting paths are continuous on aircraft?
Bonding wires
What key component prevents differential electrical charge on aircraft?
Bonding wires
What dissipates static charge into the atmosphere?
Static wickss
What do static wicks do?
Dissipate static charge
In terms of electricty, what kind of material are aircraft tyres?
Conductors
What do aircraft tyres do on landing in relation to electricity?
Earth built-up static electricity
What kind of instruments are not electrically powered?
Pitot-static instruments
Are pitot-static instruments electrically-powered?
No
