021 02 Electrics & Electronics

Static: Imbalance of electric charges within or on the surface of a material.

Dynamic: Electrons in motion.

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.

ACFT is statically charged due to...

1. friction between the air and the ACFT surfaces - in-flight
2. 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

Depends on...

• 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)
• Temperature
  • Metalls: High temperature = higher resistance (and vice-versa)
  • Semi-conductors: High temperature = lower resistance (and vice-versa)

W = U * I * t [kWh]

P = W / t = U * I [W]