Both personal and commercial aircraft feature an immensely complex electrical system that supports both vital avionic equipment and nonessential systems. With a combination of batteries, generators, alternators, electrical buses, and an intricate network of monitoring devices, nearly every region of the aircraft is integrated with electrical wiring or other similar elements. Given the significance of this self-contained network of components, it is critical for anyone involved in aviation to have a baseline understanding of how electrical power is generated, stored, and distributed throughout the aircraft. In this blog, we will discuss the various parts associated with the aircraft's electrical system
Often confused with generators, the alternators are engine-driven energy sources that generate the necessary current for the various electrically-powered aircraft systems. They operate by creating an alternating current through the rotation of a magnetic field inside a coil of wires. This highly-efficient machine is capable of producing a sufficient current to operate all aspects of the electrical system soon after the engine is turned on. Unlike generators, alternators supply a more constant output even at varying engine speeds, helping prevent over and under voltage. In order to cater to the vehicle's needs, a voltage regulator is installed on either the engine firewall or near the instrument panel.
Although very similar in operating principle to alternators, generators have the capacity to produce AC or DC energy. However, generators feature a mobile armature, causing the brushings to wear out quicker. From an economical and size standpoint, alternators outperform generators, making them the primary choice for nearly all modern aircraft.
Both the alternator and generator require the engine to be running in order to create energy. Therefore, a battery must be used to start the engine and serve as a backup energy source during periods of low generator or alternator output. It is important to note that generators tend to require higher RPMs to generate a strong enough current to power the electrical system, so aircraft not utilizing alternators are more likely to require battery input early in operations.
In the rare event of alternator failure, the pilots may disengage the system using the alternator switch. After the alternator is turned off, the plane will be running solely on limited battery power, making it necessary for the pilot to shut down all nonessential electrical equipment.
Bus Bar & Circuit Breakers
The bus bar connects the alternator, battery, or generator to all peripheral equipment. This configuration allows for separation between the distribution and receiving ends while still permitting simple wiring. Circuit breakers
function similarly to the devices found in a home, protecting equipment from transient overvoltage. Although older aircraft implemented fuses to serve this purpose, most have been replaced by safer, more effective circuit breakers.
These monitoring devices continuously monitor the alternator or generator output as well as battery charging speed. Although many aircraft are equipped with a visible ammeter, allowing the pilot to see the actual performance value, others only display a warning light upon system malfunction.
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