Aircraft Electrical systems Flashcards
What is the purpose of a circuit breaker?
The purpose of a circuit breaker is to open the circuit when an overload exists & protect the wiring.
What tool is used to measure the size of unmarked electrical wire?
A wire gage can be used to measure wires ranging in size from number zero to number 36.
What are the colors of aircraft position lights and where are they mounted?
A green light is mounted on the right wingtip, a red light on the left wingtip, and a white light is mounted in a position where it is visible from the rear of the aircraft.
What are the factors to be considered when selecting wire size for electrical power?
One factor is the allowable power loss in the line. A second factor is the permissible voltage drop in the line, and a third factor is the current-carrying ability of the conductor.
When is a circuit breaker or fuse designed to open the circuit?
A circuit breaker or fuse should open the circuit before the conductor emits smoke.
What are the three most common faults that occur in an electrical circuit?
They are open circuits, in which leads or wires are broken; shorted circuits, in which ground leads cause current to be returned by shortcuts to the source of power; and low power in circuits causing lights to burn dimly and relays to chatter.
What size electrical conduit should be used for a specific cable bundle?
To allow for ease of maintenance and possible future circuit expansion, the conduit should have an inside diameter that is 25% larger than the maximum diameter of the conductor bundle.
When should electrical switches be de-rated from their nominal current rating?
For high rush-in circuits such as circuits containing incandescent lamps, for inductive circuits that have magnetic energy stored in solenoid coils or relays, and for DC motor circuits, which draw several times their rated current during starting.
When do DC electric motors draw several times their rated current?
During starting.
What could cause an AC electric motor to run too fast?
An excessive supply voltage or the motor field windings shorted
What could cause an AC electric motor to run too slow?
Low applied voltage, defective wiring, or no lubrication.
How is the output voltage of an alternator controlled?
By using a voltage regulator to control the exciter field current and thus regulate the exciter output voltage applied to the alternator field.
What should be checked before any aircraft electrical load is increased?
The associated wires, cables, and circuit protection devices should be checked to determine that the new load will not exceed the rated limits of these units.
What is the main advantage of using AC for aircraft electric power systems?
The principle advantage is that the voltage of AC power systems is easily changed by the use of transformers. Therefore, you can transmit power at a high voltage and a low current, thus reducing the size and weight of the wiring in the circuit.
In AC power systems. How is DC obtained for battery charging?
The alternating current is changed to direct current by the use of rectifiers.
