What happens when the Overspeed Protective Device (EDM) detects excessive overspeed?

What happens when the Overspeed Protective Device (EDM) detects excessive overspeed?

• A. It reduces fuel flow to the engine but does not stop it
• B. It triggers an audible alarm only
• C. It shuts off fuel to the engine, stopping the motor
• D. It engages engine governor to limit speed

Answer: (C)

Overspeed protection must act decisively to prevent damage by stopping the engine when speed goes beyond safe limits. When the Overspeed Protective Device detects excessive rpm, it shuts off the fuel supply to the engine. Without fuel, the engine can no longer sustain operation, so the motor stops, providing a quick and reliable safeguard against overspeed-induced failure of components like turbines, blades, or gears. An audible alarm alone doesn’t stop the engine, so it doesn’t prevent damage. Simply reducing fuel flow or relying on the governor to limit speed may not stop an overspeed condition fast enough or reliably; the protective device is designed to cut fuel as the definitive protective action.

Overspeed protection must act decisively to prevent damage by stopping the engine when speed goes beyond safe limits. When the Overspeed Protective Device detects excessive rpm, it shuts off the fuel supply to the engine. Without fuel, the engine can no longer sustain operation, so the motor stops, providing a quick and reliable safeguard against overspeed-induced failure of components like turbines, blades, or gears.

An audible alarm alone doesn’t stop the engine, so it doesn’t prevent damage. Simply reducing fuel flow or relying on the governor to limit speed may not stop an overspeed condition fast enough or reliably; the protective device is designed to cut fuel as the definitive protective action.