Power Plant Sequential Trip Logic Explained

In this overview, we explore power plant sequential trip logic, focusing on a setup where the generator field breaker stays closed until a reverse power permissive is detected. This controlled shutdown process protects turbine-generator systems by ensuring the prime mover, like a steam or gas turbine, has stopped driving the generator before de-excitation. Reverse power—when the generator draws energy from the grid instead of producing it—acts as the key signal, confirmed by a relay after the turbine slows down. The sequence begins with a triggering event, like a steam loss, followed by turbine shutdown, reverse power detection, and then the field breaker opening, isolating the unit safely. This method prevents mechanical stress and grid disturbances, though it adds complexity and slight delays. It’s a smart safeguard for large synchronous generators, balancing equipment safety and system stability.