Avionics Flashcards
What is an Ion?
- A positive or negative charged atom
- Unequal number of electrons and protons
Why are atoms electrically neutral?
Equal number of electrons and protons
Explain the term electric current. When does it occur? Name the unit of measurement.
- Charge/time = current
- Potentional difference connected by a conductor
- Ampere
Explain the term electric voltage. Name the unit of measurement
- Potential difference
- Volt
What is electric power? Name the unit of measurement
- Voltage*current = power
- Watt
What is electric work? Name the unit of measurement
- Power*time = work
- Watt hour
What is an insulator or electric nonconductor? Give two examples
- No free electrons = no current possible
- Rubber, air
What is the special characteristic of an electric semiconductor? Give an example of device which use semiconductors.
- The resistance can alter
- Resistance can decrease with rising temperature
- Diodes
- Transistors
What is an electric conductor? Give two examples
- Material with free electrons in outer shell
- Copper, aluminium
Describe the single-pole conductor configuration. What are the advantages of this configuration for aircraft design?
- Positive power supply via cable
- Negative via fuselage
- Less weight and negative power supply via cable
Every conductor has an ohmic resistance. It depends on:
Conductor length
Material
Temperature
Cross section
What is a galvanic element?
Two different metals in a electrolyte
Name two types of galvanic elements
Primary cell. Secondary cell
Two identical batteries are connected in parallel. What happens?
The total voltage equals the voltage of one battery
What are the tasks of a rechargeable battery in an aircraft?
- Supply electrical system with power, without generators running (before startup, failure of generators)
- Supply starter with power during startup
What may happen to a battery, if the charging current is too high?
- Battery warms up = kaBOOOM
- Electrolyte escapes
Define the term “capacity of batteries” and state the unit of measurement used?
- How long a battery can supply power with a given voltage and current.
- Ampere hour Ah
How long can a battery supply a system with a load of 30A, if the capacity is 40Ah?
40/30 * 60 = 80min = 1h 20min
What is the nominal voltage of a battery commonly used in a helicopter?
24V (the generator = 28V)
Two identical batteries are connected in series. What happens?
The total voltage is twice of the battery voltage
Describe the working principle of a simple DC generator and name its main components.
A conductor loop is rotating in a magnetic field perpendicular to the magnetic flux lines- A voltage is induced and picked up by a commutator.
Commutator, loops, electromagnet (+exciting current)/permanent magnet
What is the purpose of a DC generator in an aircraft electrical system?
Supply electrical system with power and charges the battery during flight
Name three different types of DC generator excitation and their subgroups, if there are some.
- Self excited (parallel; series; combined)
- Direct excited
- Separately excited
Name three different types for the design of voltage regulators
- Vibrating
- Carbon pile
- Trasistorized