Training and Safety Tip: Essential electricity
Some older general aviation aircraft have generators, but most modern aircraft have alternators to power an aircraft’s electrical system.
Although both provide electrical power and charge our aircraft’s batteries, they do have some differences that you should be aware of as a part of your aircraft systems knowledge.
Generators
Used in aircraft for many years, generators operate on the principle of electromagnetic induction, where a coil of wire rotates within a magnetic field, producing a direct current. The key components of a generator include an armature, commutator, and brushes. The commutator is a rotary switch that helps maintain a steady DC output, while brushes conduct the current from the rotating armature to the external circuit.
The main advantages of generators are their simplicity and robustness, making them reliable in various conditions. However, generators have several drawbacks. As they typically need to rotate at high speeds to produce adequate electrical power, generators can be inefficient. They are also heavier than modern alternators, and their brushes and commutators require regular maintenance and replacement.
Alternators
More commonly used in contemporary aircraft, alternators generate alternating current, which is then converted to direct current using diodes. The primary components of an alternator include a rotor, stator, and rectifier assembly. The rotor creates a rotating magnetic field, inducing an AC voltage in the stator windings. The rectifier then converts this AC voltage to DC, providing a steady DC output suitable for the aircraft's electrical systems.
Alternators offer several advantages over generators. They are more efficient, especially at lower engine speeds, because they can produce higher electrical output across a broader range of rpm. Alternators are also lighter and more compact, reducing the overall weight of the aircraft. Additionally, they have fewer moving parts and do not require brushes or commutators, which minimizes maintenance needs and enhances reliability.
So, while generators were a staple in older aircraft because of their simplicity and durability, alternators have largely replaced them in modern aircraft due to their superior efficiency, lighter weight, and lower maintenance requirements.
If you are still flying generator-equipped aircraft, understand their limitations, especially when operating at lower power settings, like idling or reducing power when landing.
