How Relays and Solenoids Work and Save Aircraft Power

With the constant advancement of aviation technology, avionics, and other components, an increasing number of aircraft systems and mechanical functions are becoming more reliant on electronics. Solenoids and relays are two components that may fulfill these needs, as solenoids serve for the electromechanical interface while relays switch the electronic loads for many aircraft systems and devices. As both of these components are used in many modern aircraft, it is important to understand how relays and solenoids work, how they may save aircraft power, and how they provide functionality for various aircraft systems.

In their most basic form, solenoids are components that produce a magnetic field through a wound coil as electric current is inducted through them. Through this magnetic field, the solenoid effectively converts energy into linear motion. Often, solenoids are used as an actuator for a pneumatic or hydraulic valve, or as an electrical switch. As a switch, the solenoid may serve the starter of a vehicle, such as an automobile starter solenoid.

Relays, on the other hand, are solenoids that operate as a switch to open and close contacts and switch electronic loads. Relays may come with a variety of contact configurations with various combinations of make and break contacts. Relays are useful in applications in which a circuit is controlled by a low-power signal, or when a single signal is used to govern multiple circuits. As relays can control high voltage circuits with a low power circuit, they can be useful for saving power and energy. An example of this is within vehicles where a starter relay may control the high current of the cranking motor with much smaller wiring and contacts in the ignition key.

Relays and solenoids are considered inductive loads, meaning that they have alternating current that lags behind the alternating voltage. As compared to other loads, such as resistive or capacitive loads, inductive loads only need a certain amount of power for the load to be energized before power may be reduced. With a lower current, the time between energizing the load and deactivation is minimized. Nowadays, engineers will often design circuits specifically to have a smaller driving voltage for relays once the component is energized, thus creating power savings and to make the system more efficient.

Across all modern aircraft, electric motors are implemented so as to start the aircraft engine for flight operations. Starting an engine requires a decent amount of power, usually ranging around 100 amperes or more, thus the starter is often governed by a solenoid. With an aircraft master solenoid and battery master, the battery can power the starter to initiate operations. To initiate the starter of the aircraft, the battery contactor, also known as a master relay, is turned on and grounded so that it may provide power to the starter contactor. With the master relay, the aircraft battery may also be separated from the rest of the system, providing safety in the case of an emergency for continued powering.

When it comes time to begin sourcing the aircraft master relay and aircraft master solenoid components that you need from relay manufacturer Zodiac Sell Gmbh, Electro Switch Corp, manufacturer Guardian Electric Co Inc., and other trusted manufacturers, Purchasing 3sixty has you covered with everything you are searching for. Purchasing 3sixty is owned and operated by ASAP Semiconductor, and we can help you find the aircraft, marine, and IT parts parts that you are searching for, new or obsolete. As a premier supplier of parts for the aerospace, civil aviation, and defense industries, we're always available and ready to help you find all the parts and equipment you need, 24/7x365. ASAP Semiconductor is an FAA AC 00-56B accredited and ISO 9001:2015 certified enterprise. For a quick and competitive quote, email us at or call us at +1-434-321-4470.


April 4, 2021
January 25, 2021
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