ELECTRICAL SYSTEM Flashcards
GENRATOR OUTPUT?
Generator output is normally 115-120V/400HZ AC, 28V DC
To cover the broad spectrum of power requirements, two forms of electricity are usually required:
alternating current (AC) and direct current (DC
_______ is a form of electricity that flows in one direction (we originally thought from positive to negative, hence why negative is ground). The components of a DC system are very heavy compared to their relative power outputs.
DC: DC
_______ reverses direction. ___ power requires less current because of higher voltage and a ground neutral system. This allows the use of smaller aircraft wiring and therefore, less weight.
AC: AC
AC
Auxiliary Power Unit (APU), a small, independent gas turbine engine, provides power through a driveshaft to a gearbox that turns a backup generator. Through this generator, the APU provides electrical power and frees an aircraft from being depend on external power. The APU can also ensure aircraft power when the ____________.
engine-driven generators are not operating or fail
Generators are used as the main source for either AC or DC power. A generator transforms _________ energy into _________ energy.
mechanical
electrical
Generators frequently use a Constant Speed Drive (CSD) to maintain a constant rotational input speed regardless of engine RPM. This ensures a ______________..
steady voltage output
Inverter transforms
DC to AC
Transformer Rectifier transforms
AC power to DC (AC/DC Totally Rocks)
Battery provides ____ power, but it’s primarily used as a source of emergency power should the generators fail and also for starting the aircraft
DC
Essential bus:
routes power to equipment required for flight safety (i.e., primary attitude gyro).
Primary bus:
routes power to equipment devoted to the aircraft’s intended mission (i.e., radar).
Monitor or secondary bus:
routes power to convenience circuits, e.g., cabin lighting.
Starter bus:
routes power to start the aircraft’s engines.
Circuit breakers provide a means to manually or automatically_______ power. In an abnormal electrical situation such as an ‘overload’ or a short in the circuit (wires), circuit breakers automatically open (“pop out”), de-energizing the circuit which prevents damage to the component or the electrical system. It can also provide a manual control of electrical power to various components in case of troubleshooting, or replacement of components
interrupt
Fuses provide automatic circuit protection should an ________ or an excessive amount of current is flowing through the system or to a component
over-load
If you lose the generator and the alternator, how is the AC bus powered?
The Battery, via an inverter (converts DC to AC)
In an electrical malfunction, which bus do you lose first?
Utility bus
With a total electrical failure, what will AC read? What will DC read?
AC will read 28VAC (or 115VAC), DC will read 0
AC lies, DC dies
How many volts is a modern aircraft electrical system?
28 VDC
