What is turbine overspeed trip?
The overspeed trip is the final protection against catastrophic failure of the turbine following a load rejection, causing the unit to become disconnected from the power system. Additionally, an overspeed may be caused by a governor failure on an unsynchronised turbine causing an excessive steam demand.
How do you prevent an overspeed steam turbine?
Upgrading to a well designed electronic governor to improve speed control is a major step toward preventing a turbine overspeed. The mechanical governors can only sense speed and control the turbine at a predetermined speed.
What is overspeed trip and how it works?
An over speed trip is a safety feature provided on the diesel engine of the ship to restrict uncontrolled acceleration of the engine, leading to mechanical failure or untoward accidents.
What is the first line of defense against turbine overspeed?
10.2.2.4 Turbine Overspeed Protection System The normal speed control system (EHC) comprises a first line of defense against turbine overspeed.
What is tripping of turbine?
A turbine trip is the emergency shutdown of a power-generation turbine due to unexpected events. Due to the number of issues that may cause a trip, they are relatively common events.
How do you test an overspeed trip?
It can be tested by increasing the engine speed by speed adjuster at no load condition. Over speed trip will cut-out the fuel supply at 115% of normal speed.
What causes turbine overspeed?
A turbine overspeed accident can be caused by a lightning-induced power surge, a fouled pilot valve, an electrical fault, operator failure, or any of a few dozen other problems. Turbines are equipped with shutoff systems that are designed to automatically stop them if they exceed the design speed.
What is trip valve in steam turbine?
Throttle/trip valves provide effective flow control and emergency shut-off operation in a single, highly reliable valve assembly. In high-pressure pipe lines , such as the primary steam line serving a big, high-pressure turbine or a turbo-expander gas supply line, they are used as throttle valves.
What is overspeed relay?
When the speed exceeds the set speed, the output contacts change state, and they can be used to sound an alarm or shut the machine down. They will remain energized until the speed drops below the low speed setting, then changing state. An overspeed relay can be used to detect breakage of a belt or chain.
What is steam turbine overspeed?
The overspeed event occurs when little or no energy is being consumed by the driven equipment, whether a generator, pump or compressor, and too much steam is provided to steam turbine.
What is a trip valve?
Trip valve mechanisms are a class of steam engine valve gear developed to improve efficiency. The trip mechanism allows the inlet valve to be closed rapidly, giving a short, sharp cut-off. The valve itself can be a drop valve or a Corliss valve. Trip valve gear was applied to larger stationary engines.
What is trip valve in control valve?
by. Pressure‐sensing trip valves are for control applications where a specific valve/actuator action is required when supply pressure falls below a specific point. When supply pressure falls below the trip point (see below figure), the trip valve causes the actuator to fail up, lock in the last position, or fail down.