Definition
A compound-wound DC generator in which the series and shunt field windings are balanced so that the output voltage at full rated load is approximately the same as the output voltage at no load. The series winding adds just enough magnetic field strength under load to offset the voltage drop that would otherwise occur, keeping terminal voltage essentially flat across the operating range.
Plain English
A type of DC generator built so its output voltage stays about the same whether very little electrical equipment is running or the full rated amount is running.
Context Anchor
Seen in aircraft electrical-system and maintenance discussions, especially with older direct-current generator systems and voltage regulation.
Derivation
Flat' refers to the shape of the voltage-versus-load curve — it stays level rather than rising or falling. 'Compounded' means the generator uses two field windings working together (a shunt winding in parallel and a series winding in series with the load). The combination is tuned so the curve comes out flat.
Why Pilots Care
Provides stable power to instruments, radios, and lights without frequent voltage adjustments as loads change in flight.
Analogy
It is like a water system that keeps the pressure about the same whether one faucet is open or several are open.
Intuition Check
Flat does not mean the generator is physically flat. Here, flat means its voltage output stays nearly level as the electrical load changes.
Example Sentence 1
The aircraft's flat-compounded generator held bus voltage steady even as the pilot switched on the landing lights and pitot heat.
Example Sentence 2
During preflight, the pilot confirmed the flat-compounded generator was maintaining 28 volts with all systems running.