Airframe Systems & Components: Aircraft Electrical Systems 🔊 Flashcards
What is the purpose of a circuit breaker?
To protect the circuits and wires from fire
What are the two principles on which circuit breakers operate?
Thermal and magnetic
What tool is used to measure the size of unmarked electrical wire?
A wire gauge
What are the colors of aircraft position lights and where are they mounted?
Green on the right, red on the left, and white on the back
What are the factors to be considered when selecting wire size for electrical power?
Allowable power loss in the line, permissible voltage drop in the line, and the current carrying ability of the conductor
When is a circuit breaker or fuse designed to open the circuit?
Before the conductor emits smoke
What type of breakers are not acceptable for use in aircraft?
Auto reset breakers
What is a slow blow fuse?
A fuse that compensates for surges and high inrush current by not blowing for several milliseconds
What are the three most common faults that occur in an electrical circuit?
Open circuits (wires are broken), shorted circuits (ground leads cause current to be returned by shortcuts to the power source), and low power (lights burn dimly and relays chatter)
What size electrical conduit should be used for a specific cable bundle?
Allow for ease of maintenance and possible future circuit expansion, conduit should be 25% larger than the maximum diameter of the conductor bundle.
What color insulator on a solderless connector is proper for a 10-gauge wire?
Yellow
How should electrical switches typically be oriented in the on position?
Up or forward
When should electrical switches be de-rated from their normal current rating?
High rush in circuits such as those containing incandescent lamps (landing lights), and 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 would cause an AC electrical motor to run too fast?
An excessive supply of voltage or the motor field windings shorted
What would cause an AC electrical 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?
Check to determine the new load will not exceed the rated limits of the associated wires, conductors, and circuit protection
What is the main advantage of using AC for aircraft electrical power systems?
The voltage is easily changed using transformers, thus reducing the size and weight of the wiring in the circuit
In AC power systems, how is DC obtained for battery charging?
AC is changed to DC using rectifiers
What warns pilots of overheating batteries?
A thermal sensor in the battery and a light in the cockpit
How long should bonding jumper wires be made?
Large enough to handle all return current flow and as short as possible to prevent an increase in resistance
What are two items that wear on a starter generator?
Commutator and the brushes
What powers the ELT?
The ELT battery
What is the purpose of a static wick?
It dissipates static energy to avoid damaging electrical components
What are two types of AC generators?
Single phase and three phase
When repairing aircraft electrical components what reference do you use?
The manufacturer’s maintenance manual
