Page 431 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Steam Turbines and Turboexpanders 409

Spring loaded flyweights sense the turbine speed. When the speed
changes, centrifugal force causes the flyweights to pivot outward or in-
ward. The flyweights actuate the pilot valve plunger which opens or
closes a control port in the pilot valve bushing. The control port directs
the control oil to or from the bottom side of the power piston.
The power piston is connected through linkage to the rotary terminal
(output) shaft. Control oil moves the power piston. The motion is trans-
mitted mechanically through the terminal shaft and connecting governor
valve linkage, to position the turbine governor valve.

Initial Start-up (Refer to Figure 8-20)

1. Fill the governor with oil and check for signs of leakage.
2. Check the governor linkage for ease of movement.

PILOT VALVE

HAFT LEVER
ABLE
NO Roo

LEGEND

HIGH PRESSURE OIL
CONTROLOIL
RESERVOIR OIL

Figure 8-19. Governor schematic.