Page 321 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Steam Turbine Best Practices Best Practice 5 .11

Fig 5.11.18 Overspeed detection (Courtesy of Elliott Co.)

continuous speed). Centrifugal force resulting from high shaft
speed will force the trip lever, which will allow the spring-
loaded handle to move inward. When this occurs, the port in
Loss of control oil pressure the handle stem will allow the control oil pressure to drain
Spring force automatically overcomes oil force holding valve open and drop to zero. The high energy spring in the trip and
(approximate set point 50–65% of normal control oil pressure) throttle valve, normally opposed by the control oil pressure,
Manual trip (panic button)
Manually dumps control oil on command will close suddenly (less than one second). In this system
Optional there are two other means of tripping the turbine (reducing
Turbine excessive axial movement control oil pressure to zero):
- Manually pushing spring loaded handle
Fig 5.11.19 Internal protection - Solenoid valve opening

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