Turbine crisis circuit breaker handle
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As handle-type shutdown devices, are the crisis cut-off switch handle and the manual emergency shutdown handle redundant? What are the benefits of having both at the same time? (If an additional shutdown option were to be added, it doesn’t seem feasible, as there are already the soft and hard controls in the control room, as well as emergency shutdown buttons on site.)
I recall that the handle of the crisis cut-off device can be activated not only manually but also by a weight attached to the turbine rotor. When the turbine’s speed reaches the mechanical trip speed, the weight on the rotor moves and triggers the crisis cut-off device, causing the turbine’s speed control valve to close and shut down the turbine. Many turbines have mechanical trip tests, which are conducted to verify this mechanism; it can be considered a hardware-based interlock system, representing the final line of defense against a runaway turbine. The shutdown test triggered by an excessive rotational speed as measured by the corresponding speed gauge is called an electronic trip shutdown test. However, many turbines these days no longer have this feature, and even if they do, there are no reports of mechanical shutdown tests being conducted.
I can’t remember exactly; I worked on the steam compressor station in the early 1990s. During an emergency shutdown, what was done on-site was to press the handle of the emergency cut-off device. It was a Demag unit, and I don’t recall there being another emergency shutdown handle as well.
The crisis cut-off handle and the manual emergency shutdown handle are essentially the same thing – the handle used to cut off the oil supply at the turbine head, which is connected to mechanical interlocks for shutdown in case of overspeed or shaft displacement.
One is for safety and self-protection, and the other is for manual shutdown; they are different
The emergency shutdown valve handle is located at the shaft end of the turbine; some turbines’ emergency shutdown valves do not have a handle； The emergency stop handle is on the quick-shut assembly.