Electrical System Flashcards
What is the purpose of the battery?
Supplies power for the starter motor and acts as a backup if the alternator fails
What are the two types of batteries and which one is most common on most modern planes?
24 volt and 12 volt.
24 volt is most common on modern planes. Some older planes may have 12v
Most vehicles have 12v batteries…could you use a car to jump start your plane?
Only if my plane also has a 12v battery
What does an alternator do?
Alternators produce electrical power/current even at low RPM (which is why they are prefered to generators).
During flight, the alternator provides components like lights, flaps, gear, avionics, de-icing equipment, etc, with electrical power and recharges the battery.
Why are generators more suitable to jet engine aircraft/turbine engines?
Generators only produce electricity in a very specific and small range of RPM settings. Because these types of engines spin at very high RMP values constantly, it will be most efficient to use a generator.
The master switch has the Alternator on the left and the Battery on the right. Which of them can be turned on an off independantly?
The battery can be turned on independantly of the alternator. Turning off the battery turns off both sides.
The alternator cannot be on unless the battery is also on.
What is the ammeter telling you if it shows a negative/discharge?
The alternator is not working and all the electrical equipment is drawing directly from the battery
After showing a discharge on the ammeter, you cycle the master switch. If the alternator comes back on line, what will the ammeter likely show?
A more positive charge than usual, as the battery was drained and is now refilling.
Some AC dont have an ammeter, they have a loadmeter. What is a loadmeter?
It counts the total of each componant (radio, lights, turn coordinator etc) that it is supplying power to.
If your alternator fails, what would a loadmeter show?
A defelction of 0, because electicrity passes through it from the alternator.
What does a full scale positive deflection on the ammeter mean?
It indicates a malfunction of the voltage regulator
What is the purpose of the voltage regulator?
It controls the rate of charge to the battery by stabilizing the alternator electrical output.
The output should be higher than the bettery voltage. Example: a 12v battery would be fed by an alternator system of 14v. In a 24v battery, it would be 28v.
The difference in voltage keeps the battery charged.
If you have a hard positive deflection on your ammeter and suspect a voltage regulator malfunction and cycling the master does not fix it, what should you do?
Turn off the alternator side of the master. Without the voltage regulator, the alternator could fry the electrical system and battery.
Most modern AC have circuit breakers. What did/do old AC have?
Fuses
Why do you have to make sure all your electronics are off before starting the engine?
Because the voltage regulator sends a burst of electricity to the alternator to start it. If it happened to keep going it would fry your electronics
