Ordnerverwaltung für 021 02 Electrics & Electronics
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Static vs. Dynamic Electricity
Static: Imbalance of electric charges within or on the surface of a material.
Dynamic: Electrons in motion.
Static dischargers (static wicks)
A plane builds up static electrical charge during the flight by friction between the air and the surfaces of the plane. --> Static dischargers reduce the build up of static electricity by dispensing the charge into the atmosphere.
Grounding / Bonding
ACFT is statically charged due to...
friction between the air and the ACFT surfaces - in-flight
friction between the fuel and the fuel pumps, pipes and filters it runs through causes positive charged fuel ions to enter the fuel tank
--> ACFT parts are connected by flexible wire strips to distribute the static charge equally across the whole ACFT to keep it at similar potential. --> On ground ACFT is grounded to dispose of the static charge
= difference of potential --> On one side there is a surplus of electrons (=Minuspol), on the other side there is a shortage of electrons (=Pluspol)
= electrons per time
Physical current = Movement of electrons from Minuspol to Pluspol Technical current = Movement of electrons from Pluspol to Minuspol
DC = Direct current --> For low voltage consumers, e.g. PFD AC = Alternating current --> For high voltage consumers, e.g. generators/motors
Every conductor has a maximum allowable current. --> Depends on the material and cross section
= obstruction of the flow of electrons
Specific resistance of the material \(\rho\) (Depends on the number of free electrons)
Lengt L of the conductor (Longer = Higher resistance)
Cross section A of the conductor (Larger = Lower resistance)
Metalls: High temperature = higher resistance (and vice-versa)
Semi-conductors: High temperature = lower resistance (and vice-versa)