🔍 Key Concepts

• Overspeed trip function on steam and gas turbines • How rotational speed is sensed in mechanical protection devices • Difference between mechanical (centrifugal) action and pneumatic/hydraulic control systems

💭 Think About

• Ask yourself: which of these forces or systems can directly respond to a shaft spinning too fast without needing external controls or signals? • Think about classic mechanical governors on engines and turbines—what physical principle do they use to detect overspeed? • Which option is more commonly associated with control or actuation systems, rather than with the primary sensing of overspeed?

✅ Before You Answer

• Identify which choice is tied to rotational motion itself, not pressure in a line or casing. • Separate in your mind the sensing element from the actuating medium—the question is about what actuates the device automatically. • Verify which force type would increase predictably with RPM (revolutions per minute) of the turbine shaft.