All About the Aircraft Electrical System

When discussing electrical systems, it is important to be aware of some basic terminology. Voltage refers to electrical pressure, and it may be measured in volts. Current is the movement of electrons, and it can be measurable with amps. Resistance is the opposition to current flow, ensuring that electricity is governed throughout the system. Lastly, power is the rate of electricity, often expressed in Watts.

In order for the electrical system to efficiently transfer and supply electricity, it relies on both equipment and power supply circuits. The equipment circuits are what transfer electricity to various components, and they receive energy from bus bars that are dependent on generators and batteries. The power supply circuits are those related to the generator and battery assemblies, and they utilize transformers and rectifiers as they furnish bus bars with power. The primary power utilized by the aircraft electrical system may come from a few sources, most commonly being generators driven by aircraft engines, rat air turbines (RAT) driven by ram air, or auxiliary power units (APU). During standard operations, power will primarily be derived from the generators of aircraft.

Generators are a type of apparatus that is capable of transforming mechanical energy into electrical energy through the process of electromagnetic induction. Depending on the type of generator, either AC or DC power can be produced. For some parts of the electrical system, electrical power may be used to create mechanical energy, and this is achieved with the use of motors.

The aircraft battery can come in a variety of forms such as NiCd and lead acid types, and they are composed of numerous cells that convert chemical energy into electrical energy. With primary and secondary cell types, electrons are exchanged through the chemical action of an electrolyte and electrode materials. As primary cells destroy active materials, the battery types used in aircraft are typically secondary cell types.

Beyond batteries and generators, many smaller electrical components are paramount to the overall functionality of the aircraft electrical system. With the bus bars, electricity is provided from the generators and batteries before being passed onto various electrical services. As certain components may specifically require either AC or DC power, rectifiers are placed in the system to convert AC to DC. DC to AC transformation can be achieved with components known as inverters, and they may either be rotary or static in their operation. With transformers, alternating current can be transferred from one circuit to the next with the use of inductively coupled electrical conductors.

In order to isolate circuits, direct current, or generally manage electricity, switches are used. Depending on the type of switch present, a number of processes may be carried out. Proximity switches are an example that assist in cargo door, landing gear lock, and passenger door operation, and they operate similarly to other switch types such as micro-switches. Relays are a form of electro-mechanical switch, and they are capable of controlling a large amount of current through the induction of a small amount of current. Contractors are similar to relays, and they may be used for applications such as connecting battery power to the aircraft.

In order to protect all electrical systems and elements, engineers implement a number of circuit breakers and fuses. Circuit breakers are devices that detect electrical faults and then automatically break the circuit to stop the flow of current. As a reusable device, the circuit breaker can be reset before it is used again. Fuses, on the other hand, are sacrificial devices that interrupt circuits when a fault is detected by having their element melt under excessive current loads. As the circuit will break upon the melting of the fuse, sensitive components may be protected and the fuse will simply need to be replaced before normal operation can resume.

At Infinite Instrustrials, we are a streamlined purchasing platform offering customers unmatched services and competitive pricing on all we carry. We invite you to peruse our expansive part and manufacturer catalogs, and you may request quotes at any time through the submission of an Instant RFQ form. Once received, a member of our staff will review and reach out to you in 15 minutes or less with a personalized solution.