Basic Jet Electrical Flashcards
What is the difference between A/C and D/C electricity and which is better from an Airliners perspective ?
A/C is better due to it being more lightweight, and safer in use with the ability to increase or decrease voltage by a transformer and an overall decrease in current. It also results in less power loss when transmitting.
Which one kills you, amps or volts?
Amps but you need both. you need enough voltage (potential) to push the amps through your body. Welders have high amps, low volts, you can feel it, but it doesn’t have the potential to go through you
Your battery is XY amp/hours. What does that mean?
Amp-hour ratings measure a battery’s electrical capacity, similar to how you rate a bucket’s water capacity in gallons. These ratings can be expressed in different values as long as the product equals the total capacity. For example, a 20 amp-hour rated battery can discharge 20 amps of current for 1 hour. Rarely will you load this battery to the full 20 amps. So, more practical ways to express this are: 1 amp of current for 20 hrs; 5 amps for 4 hrs; 10 amps for 2 hrs; 6.66 amps for 3 hrs, etc. This is why it’s important to reduce electrical load (amps) when running on battery alone during an electrical system failure.
What is a KVA?
kilovolt-amp. kVA is a measure of the apparent power (what it’s capable of) output of the generator whereas watts are a measure of the real power (what you’re actually getting). In a DC system apparent and real power are equal (power factor = 1). In an AC system, real power (watts) are usually less than apparent power (VA) due to inefficient electricity transference.
What are the different types of batteries?
Lithium, Nicad, Lead
What are the disadvantages of a lead acid battery?
Voltage supplied tapers off the longer the battery is discharged
Why are modern jets mostly AC , not DC?
AC equipment is generally smaller, lighter weight and simpler in design than DC. It’s more easily generated by engine generators and can travel further distances. The higher cycles (400 vs 60) of AC to DC are less disruptive to the human body.
What are the advantages of a lead acid battery?
Cheaper and not as susceptible to overheating as NiCad
What is generally powered by DC?
Battery
Why is a DC system used in GA aircraft over AC?
Simpler in design and operation compared to AC systems. This simplicity translates to fewer components, which can reduce potential failure points and maintenance requirements.
The straightforward nature of DC systems enhances reliability.
Small GA aircraft typically rely on batteries for their electrical power when the engine is not running. Batteries naturally produce DC power, making it straightforward to integrate into the aircraft’s electrical system without the need for inverters to convert DC to AC.
Lower Cost
How does a transformer work?
A transformer is made up of roughly three components:
- Primary Coil
- Secondary Coil
- Magnetic Core
When AC flows through the primary coil of a transformer, it creates a changing magnetic field in the core of the transformer. The changing magnetic field in the core induces a changing magnetic flux. This flux links with the secondary coil. The induced voltage’s magnitude depends on the number of turns in the coil and the rate of change of the magnetic flux. By adjusting the number of turns in the primary and secondary coils, the transformer can step up (increase) or step down (decrease) the voltage.
What is a diode?
Like a check valve for liquids, it only allows current to flow in one direction.
What is a rectifier?
A device that changes wavy AC electricity into smooth DC electricity.
What is a capacitor?
A little tank that smooths out the electricity bumps and distributes the current evenly.
Why do GA aircraft utilize alternators whereas commercial airliner jet aircraft utilize generators?
Alternators are simpler and cheaper
lighter and more compact
Alternators produce power more efficiently at lower engine speeds
Although alternators generate AC, they include built-in rectifiers to convert AC to DC
