Test Review Flashcards
What is the definition of a governor?
An automatic attachment for controlling speed
What does the governor oil system consist of?
- pump
- sump tank
- oil piping
- pressure tank
What are 4 visual signs of oil deterioration?
- varnish
- sludge
- dark cloudy color
- dirty filter
If the load on the turbine is suddenly dropped, what happens to the speed of the governor ballhead?
Increases instantly
If the governor is regulating a single generator with its own load, will it have speed drop?
No
Where does a governor get its sensitivity?
Flyballs
A compensating dashpot is a device used to achieve ______ of the governing unit.
Stability
What is the function of the pilot valve in a hydraulic governor?
Provides hydraulic force to the relay valve
True or False:
A generator with 5% speed drop will sense a change in load.
True
What does the dashpot consist of?
Needle valve and two pistons
List four safety devices in a hydraulic turbine governor system.
- overspeed
- broken belt device
- low oil pressure switch
- nozzle deflector
What is the purpose of the vibrating disks?
stability and lubrication
The auxiliary valve is used in a hydraulic governor system to…
Manually operate the gate servomotor
What is the main function of the PMG?
To supply electric power to operate the ballhead motor
Where is the speeder spring located?
Next to the flyballs
What is the function of the restoring mechanism in a hydraulic governor system?
To recenter the pilot and relay valves
What is the gate limit device used for?
- control the opening of the gates during startup
- prevent overtravel
- control gate position from a remote location
True or False:
If the needle valve in the dashpot has been adjust correctly it will allow the small plunger to recenter in the same interval that the speed drifts back to normal.
True
True or False:
The governor ballhead must turn at the same RPM as the PMG.
False
What position the relay valve and how does it do it?
The pilot valve hydraulically positions the relay valve
As a hydraulic governor system functions, the relay valve plunger moves downward and the pilot valve restoring linkage moves the pilot valve bushing downward until…
the ports in the bushing are closed
Names four qualities of good governor oil.
- lubricates
- does not precipitate solids
- does not break down
- dissipates air
True or False:
The ballhead is a speed sensing device mechanically connected to the relay valve that changes the speed of the unit.
False
True or False:
The needle valve in the dashpot provides a means of adjusting the speed or movement of the wicket gate.
False
The servomotor is a ______ cylinder
Double-acting
If the system is sluggish in response to speed changes, what is the issue?
The spring on the compensating dashpot is too tight.
True or False:
A floating lever is a lever with several independent fulcrum, none of which are fixed.
True
The compensating dashpot provides ______ restoring.
temporary
Name four basic parts of a simple governor.
Flyballs, speed changer, oil pressure system, servomotor, pilot valve, relay valve, restoring mechanism, gate limit device
