What Is Electromagnetic Induction?

As aircraft continue to advance with new and improved technology being implemented all the time, many models are becoming increasingly electrified. While early aircraft were primarily mechanical, modern assemblies take advantage of electrical systems to position flight controls, measure atmospheric conditions, drive HVAC systems, and much more. Magnetism is another major element of aircraft system operations, magnetic fields often being used to create energy and power that is necessary for electronic systems to function as intended. As a result of the extensive use of electronic components and magnetic fields, it can be useful to have an understanding of electromagnetic induction and its effects.

When discussing electromagnetic induction, one is referring to the generation of an electromotive force across an electrical conductor that is present within an adjusting magnetic field. Variations of a magnetic field can occur as a result of a relative motion between the conductor and magnetic field source, and this is a principle of electrical generators as they vary the strength of a field for the means of producing a constant voltage. In order to adjust a magnetic field, one must change the current being induced. Self-induction is a common way to do this, and it can be done when the conductor is a part of an electric circuit.

When adjusting the current within a particular circuit, one may also cause an Electromotive Force (EMF) to be induced in a second circuit that is unconnected and nearby. This form of electromagnetic induction is known as mutual induction, and it is a common source of aircraft system anomalies. If one is discussing electrostatic induction, they are referring to when an unbalanced electric charge enters a previously uncharged metallic body as a result of a charged object being too close.

As countless modern aircraft systems are dependent on electrical power and components, it is extremely important that unwanted electronic signals are not induced. This can often corrupt the output of certain devices, causing various issues. As a real-world example of an error that resulted from electromagnetic induction, a business aircraft once faced issues involving false warning signals that were caused by induction. Often, the crew saw that they were receiving “fuel filter clogged” warnings, and every inspection they did resulted in no contamination being found. When taking the time to thoroughly inspect all wiring systems and computers, replace various parts, and test systems, it was eventually determined that the batteries were causing issues as new batteries would solve the problem. This was eventually found to be a result of induced voltage spikes as a result of lost cell capacity over time with continuous use, causing the sensing computer to detect a threshold voltage for activating the alarm circuit.

Alternating current systems are also a major source of unwanted induced AC system signals, and it is important that there is a means of managing synchronization within the assembly. If co-located electrical conductors begin to have potentials that rise and fall at varying times, mutual induction has a higher chance of occurring. In instances where mutual induction occurred, pilots have faced issues where magnetic heading systems deviated or other instruments performed in a way that was not intended. As a result, eliminating induction effects is crucial.

Generally, proper spacing of conductors and AC power systems can be beneficial, though other solutions such as the Faraday Cage are also useful. By placing systems and components within a grounded metal box, stray charges are prevented from entering contained circuitry. Beyond the Faraday Cage, one may also protect wires with metallic shielding.

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