What Is an Aircraft Electrical System?

The electrical system is a complex network of wires and devices that plays a vital role in every aircraft. Without an electrical system, a modern aircraft would be limited in its capabilities and functionalities.  The electrical system is responsible for the operations of lights and other vital systems, including GPS, communication systems, and all the functional features of avionics systems. Additionally, electrical systems also support mundane processes such as engine ignition and the functionality of the auxiliary fuel pump.

The Aircraft Electrical System

An electrical system on an airplane is like a small world of electronics. It has everything from batteries for generating power to transformers that distribute it throughout the aircraft in all different phases of flight. The electrical system on an aircraft is designed to keep the flight safe and sound. There are two sources of power: A battery, which usually works when engines are not running and an alternator or DC generator which provides continuous power for various components of your aircraft – from lights to instruments at the cockpit level.

How Does an Aircraft Electrical System Work?

The aircraft’s electrical system should be self-sufficient, as batteries have a finite capacity and can discharge after some time while being used. Installing generators or alternators on board can distribute a power supply efficiently in the aircraft. The power supply can be used for the illumination of lighting and charging batteries to use when needed.

All aircraft electrical systems have components that can generate electricity. Depending on the type of plane, generators of alternators provide power to run various equipment in your flight deck and can be powered by an APU (Auxiliary Power Unit), hydraulic motor (Disc),or  Ram Air Turbine (RAT). The power output from these devices is typically 115V at 400HZ AC input with i28 Volts DC output. The power from a generator can be used without modification, or it may go through transformers, rectifiers, and inverters to change the voltage and type of current.

The generator is used for charging batteries and it also provides a backup power source in an emergency. There are two types of batteries: lithium batteries and lead acid or Ni-Cd batteries. Lithium batteries are commonly used as their storage capability is better than their counterpart. The stored energy can be used during the start up of an aircraft as well as in emergency situations (their energy being needed most in the event of generation or distribution system failure). 

Basic Aircraft Electrical System

The single-engine aircraft is self-powering and has no electrical system. Generally, a single-engine aircraft will be equipped with a magneto ignition system, which means it does not require electricity. The fuel tank for this type of piston motor resides in an accessible location for gravity feeding, and the engine is started with a flywheel or hand crank arrangement to get things going before utilizing the magneto ignition method.

When it comes to electric starters, lights, and flight instruments, there is no choice but the electrical system. This means that you will need a DC-powered single distribution bus with a battery or generator driven alternator in most cases. The generator/alternator will have provisions for an on/off switch so that the battery can be isolated from it. In addition, there is an ammeter or warning light that provides an indication of when a charging system is failing, alerting you if anything goes wrong with the charging of the battery and current moving from the battery and through the bus bar. Provisions may be provided to allow an external power source such as a Ground Power Unit (GPU) or extra battery to connect wirelessly and provide assistance with starting your engine when you need it most.

Advance Aircraft Electrical System

Advanced aircraft require multiple voltage systems, hence they need more sophisticated electrical systems such as a combination of AC and DC busses to power several aircraft components. During flight, the generator power is usually AC which is converted into DC voltage using one or more Transformer Rectifier Units (TRU) to power the DC busses.

When an aircraft is on the ground, AC power is generated from an APU to power systems and is used while airborne in the event of component failure. Another power generation system is tertiary generation which provides a constant electric supply in the event of multiple functional failures. The power is generated from a hydraulic motor or RAT.

In such circumstances, essential AC and DC components are wired to specific buses and special provisions are made to charge these buses in the case of an emergency. If all power generating systems are lost, then a static inverter acting as an AC bus will be charged with the aircraft batteries. The electrical system is designed with robust monitoring capabilities that will alert pilots in any emergency. These warnings may include generator failure, TRU failure, battery failure, bus fault/failure, and circuit breaker monitoring.

Conclusion

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1. mary wilson
2. Posted on February 24, 2022
3. aviation

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