Speed
Governor is an electromechanical device in diesel engine. Its function is to
maintain & control the speed of the engine by controlling the amount of
fuel to engine.
The
core concept in power generation is that, the speed of engine or turbine must
be constant or +-x of it. A fluctuation in speed would cause fluctuation in
voltage and frequency.
Fig: Typical
diesel engine
Governor
maintain the speed of running engine by controlling the amount of fuel supply
to engine. If the speed is low or high other than nominal value, then it
increase or decrease the amount of fuel to engine. The signal governor receives
from a certain control system.
Governor working principle
During
normal operation the engine speed is controlled by a governor (1) which
regulates the injected fuel quantity to correspond with the load and engine
speed.
The
regulation movement is transferred to the control shaft (10) through a
adjustable link rod (2).The movement from the control shaft, to the injection
pump fuel racks (15), is transferred through the regulating lever (6) and the
spring (7).
When one of fuel rack is jammed
The
torsion spring (5) enables the control shaft and, consequently, the other fuel
racks to be moved to a stop position, even if one of the fuel racks has jammed.
In the same way the torsion spring (7) enables the regulating shaft to be moved
towards fuel-on position, even if an injection pump has jammed in a no-fuel
position. This feature can be of importance in an emergency situation.
Engine
stop control with governor
The
engine can be stopped by means of the stop lever (16). When the stop lever is
moved to stop position, the lever (17) actuates the lever (9) forcing the
regulating shaft to stop position.
1. Governor,
2. Adjustable link rod, 3. Lever for governor, 4. Screw, 5. Spring, 6. Lever
for injection pump, 7. Spring, 8. Bearing housing, 9. Lever, 10. Control shaft,
11. Load limiter, 12. Lever for control shaft, 13. Adjustable link rod, 14. Adjusting
screw, 15. Fuel rack, 16. Stop lever, 17. Lever for stop lever, 18. Dog
Electro-pneumatic
tripping device for Engine
The
engine is provided with an Electro-pneumatic device with tripping speed about
15 % above the nominal speed. The electro-pneumatic device moves every fuel
rack to a no-fuel position by means of a pneumatic cylinder on every injection
pump. The cylinder actuates direct on the fuel rack. The electro-pneumatic
device can also be tripped manually
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