In the context of aviation and aerospace, an "Air-Driven Generator" (ADG) is a type of generator that uses the energy of compressed air to drive an electrical generator. The compressed air is typically bled from the aircraft's engines or auxiliary power unit (APU).

Here's how it works:

1. Compressed air from the engine or APU is directed into the ADG.
2. The compressed air expands through a turbine, which is connected to a generator.
3. The turbine drives the generator, producing electrical power.
4. The electrical power is then used to power the aircraft's electrical systems, such as lights, communication equipment, and navigation systems.

Air-Driven Generators are commonly used in aircraft because they:

• Provide a reliable source of electrical power
• Are relatively lightweight and compact
• Require minimal maintenance
• Can be used to start the aircraft's engines or APU

ADGs are typically used in conjunction with other power generation systems, such as battery-powered systems or ram air turbines (RATs), to provide a redundant and reliable source of electrical power for the aircraft.

It's worth noting that Air-Driven Generators are also used in other industries, such as industrial power generation and oil and gas production, where compressed air is available and can be used to drive a generator. However, in the context of aviation and aerospace, ADGs play a critical role in providing reliable electrical power for safe and efficient flight operations.