In order to ensure the best reliability of the tripping system, please use multiple Steam Solenoid Valves in parallel, and each solenoid valve is equipped with an online electromagnetic testing device.
If the Steam Solenoid Valve should be opened, a solenoid valve installed in the control oil system will falsely trip the turbine. If the valve cannot be opened as instructed, it will cause catastrophic damage.
Installing two solenoid valves in parallel with another valve in series in each circuit (four solenoid valves in total) will achieve the highest reliability of the tripping system because this will provide the best guarantee that one valve will open according to the command, and Can prevent accidental solenoid valve opening.
In addition, an online solenoid test for each valve every three months can best ensure that the solenoid trip system will function when necessary.
The function of the steam turbine protection system is usually confused with the control system, but the two systems are completely separate. The protection system only operates when any control system setpoint parameter is exceeded, and if the steam turbine continues to run, the steam turbine will be damaged.
The protection system monitors the main train parameters of the steam turbine and adopts the following measures to ensure safety and reliability:
Start (optional) can provide a safe and reliable fully automatic start, and shut down the turbine in case of any abnormal situation
Water Rotameter allows to confirmation the movement of the trip valve stem during operation without stopping the machine
Rotor Overspeed monitors the turbine rotor speed and shuts down the turbine when the maximum allowable speed (trip speed) is reached
Excessive process variable signals will monitor all train process variables and turn off the turbine when the maximum value is exceeded
The multi-valve, multi-stage turbine protection system incorporates a mechanical Overspeed device (trip pin) that can shut down the turbine when Overspeed (higher than 10% of the maximum continuous speed). The centrifugal force generated by the high shaft speed will force the trip bar, which will cause the spring-loaded handle to move inward. When this happens, the port on the handle rod will allow the control oil pressure to drain and drop to zero.
The high-energy springs in the trip valves and throttle valves, which are usually resisted by the control oil pressure, close suddenly (less than 1 second). In this system, there are two ways to trip the turbine (reducing the control oil pressure to 0 psi):
Manually push the spring handle
Solenoid valve opening