What happens if the throttle control is not used to regulate steam flow?

• A. Uncontrolled steam flow could lead to overspeed and potential damage
• B. The turbine will automatically compensate and no risk
• C. Efficiency will always improve
• D. Steam will stop completely

Answer: (A)

Without using the throttle to regulate steam flow, there’s nothing to limit how much steam the turbine receives as load changes. The result is the potential for the turbine to speed up beyond its design speed (overspeed), which puts excessive stress on the rotor, blades, and bearings and can lead to damage or a forced shutdown. A governor or automatic controls can help, but they do not eliminate the risk if the throttle isn’t used to keep steam flow in check. Efficiency isn’t guaranteed to improve with unregulated flow; the system can operate at an improper speed and produce wasted energy. Steam won’t stop completely just because the throttle isn’t used—the flow would still respond to boiler pressure and other factors, but it would be uncontrolled and unsafe.