Which of the following speed control devices is used strictly as a safety device to prevent prime mover damage and acts by shutting down the prime mover?

Correct Answer: Option C — Over speed trip

An overspeed trip is a dedicated safety mechanism designed to physically disconnect the fuel or steam supply to a prime mover if it exceeds a critical RPM. Unlike a governor, which modulates speed, the trip is a binary safety device intended to prevent catastrophic mechanical failure during runaway conditions.