Electrical Flashcards
Current (I)
The flow of electric charge measured in Amps
Voltage
The difference on potential energy between two points, required to make a currnt flow
Two types of currents
Direct Current
Alternating Current
Direct Current DC
Flowing in one direction
Alternating current AC
A current that changes direction of flow at regular intervals - cycles
A DC can be converted to AC by an
DC TO AC inverter
Resistance
The degree to which a material resists electrical current. The larger the resistance the smaller the current
Conductivity
How easy it is for an electric current to pass through a material
The rate at which alternating current swithcing cycles
Frequency. Hertz (cycles per second)
AC can be converted to DC using
AC to DC. Rectifier
AC wave
Amplitude
The peak value of a wave relative to the zero position
Phase
The position of a point in time on waveform, from 0 to 360
Frequency
The power of waves produced per second
Higher frequency means ______ wavelength
Shorter
Series circuit
Components are together on the same loop
The more work the current has to do, the less the current will be
If one comp fails, no more current is transferred
Series circuit
Components are on the same loop.
The more work required, the less current will be
If one como fails the whole circuit will stop
Parallel circuit
The comoonents are placed on different branches
If one fails, the others continue to work
When an electric current passes on a copper wire it generates
Magnetic field
Motor effect
When an electric wire passes on a copper wire (generating magnetic field), and the wire magnetic field interferes with close by magnets, it causing the wire to move in right angles
If we move a copper wire between magnets,
An electric current will be induced
Flemings left hand rule
Index finger of direction of magnetic field from n to s
Second finger to direction of current
Thumb will show the direction of movement force
The bus bar is supplied current by the
Battery and alternator or generator
The components getting currents from the bus bar are eventually
Earthed
In lightweight airplanes usually the battery is
Lead-acid battery
Most battery charge is drawn during
Startup
If connecting two 12v40a in parallel circuit
12v80a, which is usually the case
If connecting a two 12v40a in series circuit
24v40a
In a generator (DC), how does it generate current
My rotating a square loop of wire between fixed magnets
Two types of DC generators
Parallel Wound(shunt) or Series-Parallel Wound(compound)
In a shunt wound generator, any increase in load will result a ____ in output ____
decrease, voltage
Field winding
A coil of wire in which the magnetic field is produced
A shunt wound generator has ___ field windings
1
The series-parallel wound takes advantage of
The two types of circuits, parallel and series
The output of series-paralell (compound) wound is relatively ______ (constant/changing) with changing load
constant
Both alternators and generators intiially generting alternate/direct current
Alternate
The windings in an alternator are stationary, the magnet rotates, and they’re called _____§
stator
In an alternator, what spins?
the magnetfic field
Most aircraft require DC/AC
DC
In order to convert ACto DC we need a
rectifier
Advantages of alternator
- Even at lower RPM, provide sufficient current
- THeoutput is more constant through engine speeds
- Lighter than generators
Disadvantages of alternator
- Requires an initial current from the battery to create a magnetic field
Ammeter
Measures the current flowing into or out of the battery
Left-zero ammeter
Shows only the output of the alternator / generator
Loadmeter
Shows the output of alternator / generator, this is the left-zero ammetere
Centre-zero ammeter
Measures the current flow into or out of the battery
Fuses and circuit-breakers should be reset how many times
Only once
If a fuse / circuit breakers/ overload switch has popped, and you smell fire,
do not insert a new fuse or reset the circuit
What’s a relay
Relays allows to control another circuit (probably a higher power one), by a smaller current/voltage circuit running through the switch.
A relay is operated on the ____ principle
Solenoid
A solenoid explanation
A metal bar with a coil of wrire around it. If current passes through the coil, the metal road moves (because of the magnetic field) which can perform mechanical tasks such as breaking or activating another circuit
If static charge is not conducted to earth
It will accumulate until it can dissipate (by touching the airframe for example will cause an electric shock)
Bonding wire
Allow the flow static electricity through the aircraft’s structure
Static charge especially build up on an aircraft when flying through
percipitation or thunderstorm
Static wicks
Small metal rods at the trailing edge of the control surfaces dissipating the static charge into the atmosphere
When the aircraft lands, the static charge
Is earthed from the tyres before someone touches the outside of the aircraft
Pitot-static insturments are using electrcity?
No
Pitot-static instruments
VSI, ASI, Altimeter
