1. Governor Control
PTC01-10 Cooling.doc
Rev. 2/7/02, jsm

2. Your Goal
To understand Governor control system design and maintenance practices for Woodward UG8 Hydraulic system, and 2301 Electronic governors.

3. WOODWARD UG8 DIAL CONTROL
SYNCHRONIZER
Speed adjusting control is used to change engine speed when running alone or to change the engine load when the engine has been paralleled with other units.
SYNCHRONIZER INDICATOR
Indicates the of revolutions of the synchronizing knob.
SYNCHRONIZING MOTOR
Option is mounted on a special cover for the governor to provide remote speed control. Its use enables the switchboard operator to match the frequency of an engine driven alternator with that of other units, or a system, before synchronizing and to change load distribution after synchronizing
SPEED DROOP
Control can be set to automatically divide and balance loads between engines or paralleled in an electrical system.
As droop is reduced toward zero the unit becomes able to change load without changing speed. As a general role, units running alone should be set to zero droop, interconnected units should be run at the lowest droop setting that will give satisfactory load division.

4. WOODWARD UG 8 DIAL CONTROL
A.C. generating units tied in with other units should have droop set sufficiently high (30 to 50 on the dial) to prevent interchange of loads between units. If one unit in the plant, or system, has enough capacity, its governor may be set to zero droop and it will regulate the frequency of the entire system. This unit will take all the load changes within the limits of its capacity and will control frequency if its capacity is not exceeded.
The system frequency is adjusted by operating the synchronizer of the governor having zero droop.
The distribution of load between units is accomplished by operating the synchronizers of the governors having speed droop.
LOAD LIMIT:
It limits the load that can be put on the engine by restricting the terminal shaft rotation of the governor and consequently, the quantity of fuel supplied to the engine. The control may also be used for shutting down the engine by turning it to zero

5. Governor Oil Specifications
Use oils which have a high viscosity index.
If oil temperature in the governor 180F, use S.A.E 40
If oil temperature above 180F, use S.A.E 50
Engine oil can be used if it meets these requirements.
OIL CONTAMINATION:
It is the major cause of governor troubles. Use only new oil or filtered oil.
Containers used for governor oil must be clean.
Anytime the governor oil appears to be dirty, drain the governor while it is hot, flush with lightest grade of the same oil, and refill with fresh oil.

6. Compensation Adjustment
After the temperature of the engine and the oil in the governor have reached their normal operating values, you can make compensation process without loading the engine.

7. Compensation Adjustment
Loosen the nut holding the compensation adjusting pointer and set the pointer at maximum position.
Remove the plug and open (unscrew) compensating needle valve three or more turns with a screwdriver.
Wait engine to hunt or serge for half a minute .
Loosen the nut holding the compensation adjusting pointer and set the pointer at maximum position. This position is called the maximum compensation.
Remove the plug and open the needle valve three or more turns with a screwdriver. The engine then will start to surge or hunts.
Wait engine to surge for about half a minute. This hunting bleeds trapped air from the governor oil passages.

8. Compensation Adjustment
4. Loosen the nut holding the compensation adjusting pointer and set the pointer at the lowest position.
5. Gradually close the needle valve until hunting just stops. Don’t go beyond this position.
6. Check the amount left to fully close the needle valve. 1/8 – ¼ turn open makes a satisfactory adjustment.
7. If hunting did not stop, raise the compensation pointer two divisions of the scale,
8. Open the needle valve again and repeat the cycle.
4. Loosen the nut holding the compensation adjusting pointer and set the pointer at the lowest position.
5. Gradually close the needle valve until hunting just stops. Don’t go beyond this position.
6. Check the amount left to fully close the needle valve. 1/8 – ¼ turn open makes a satisfactory adjustment.
7. If hunting did not stop, raise the compensation pointer two divisions of the scale,
8. Open the needle valve again and repeat the cycle.
NOTE:
Desirable opening of the needle valve is from 1/8 to ¼ turn on governors with one compensating spring and from ½ to ¾ turn on governors with two compensating springs
It is desirable to have as little compensation as possible. Closing the needle valve farther than necessary will make the governor slow to return to normal speed after load change. Also adjusting compensating pointer too far toward maximum position will cause excessive speed change up on load change.

9. WOODWARD UG8 SYCHEMATIC DIAGRAM:
MAIN SYSTEMS:
Fly Balls opens proportional with engine speed. Its opening and closing will move the pilot valve plunger up and down.
Pilot valve plunger movement will subsequently raise or lower the power piston due to the force exerted by the oil pressure.. Note that due to the difference of areas on the top and bottom of the piston, the piston will normally move up unless oil escaped to the governor oil sump.
Compensating actuating piston will act to eliminate lost motion of linkages.
Terminal shaft will rotate according to the movement of power piston. Terminal shaft rotation will increase or decrease the fuel input.

10. Governor operation normal position:
Engine is running at normal speed under steady load.
Fly balls, speeder rod, pilot valve plunger and receiving compensating piston are in normal positions; regulating port in pilot valve bushing is covered by land on pilot valve plunger.
Power piston and terminal shaft are stationary.

11. Load Increase:
Load is increased and speed decreases.
As speed decreases, fly balls move in lowering speeder rod and inner end of floating lever, thus lowering pilot valve plunger and uncovering regulating port of pilot valve bushing.
Uncovering of regulating port admits pressure oil to bottom of power cylinder; since bottom area of power piston is greater than the top area, oil pressure will move piston up.

12. Oil pressure moves power piston up and rotates terminal shaft in direction to increase fuel.
As power piston moves up, actuating compensating piston moves down and forces receiving compensation piston up, compressing compensating spring and raising outer end of floating lever and pilot valve plunger.
Movement of power piston, actuating compensating piston, receiving compensating piston, and pilot valve plunger continues until regulating port in pilot valve bushing is covered by land on plunger.
As soon as regulating port is covered, power piston and terminal shaft are stopped at a position corresponding to increased fuel needed to run engine at normal speed under increased load.

13. As speed increases to normal, fly balls return to normal position raising speeder rod to normal position.
Receiving compensating piston is returned to normal position by compensating spring at the same rate as speeder rod thus keeping regulating port in pilot valve bushing covered by land on pilot valve plunger; flow of oil through compensating needle valve determines rate at which receiving compensating piston is returned to normal.
At completion of cycle, fly balls, speeder rod, pilot valve plunger, and receiving compensating piston are in normal position; power piston and terminal shaft are stationary at a position corresponding to increased fuel necessary to run engine at normal speed under increased load.

14. WOODWARD UG8 OIL CHANGES
Oil should be clean and free of foreign particles.
Under favorable conditions, the oil may be used for approximately six months without changing.
OIL CHANGES;
Take off the top cover, remove the governor from the engine.
Drain by turning the governor up side down, and flush throughly with clean light grade fuel oil to remove any foreign matter.
Refill with fresh oil.
If it is not permissible to shut down long enough to remove the governor from the engine, drain the oil from the governor, fill with clean light grade fuel oil, run for approximately thirty seconds with the needle valve open, drain, and refill with clean governor oil.
NOTE:
If the governor is stored, it should be filled with oil

15. What is synchronization?
The matching of the output voltage wave form of one alternating current generator with the voltage wave form of another alternating current electrical system.

16. Synchronization of Engine Generator Systems
For two systems to be synchronized, five conditions must be matched:
The number of phases in each system.
The direction of rotation of these phases.
The voltage amplitudes of the two systems.
The frequencies of the two systems.
The phase angle of the voltage of the two systems.
The first two of these conditions are determined when the equipment is specified, installed and wired. The output voltage of a generator usually is controlled automatically by a voltage regulator.
The two remaining conditions; frequency matching and phase matching, must be accounted for each time the tie-breaker is closed, paralleling the generator sets or systems.

17. Number of phases:
Each generator set of the oncoming system must have the same number of phases as those of the system to which it is to be paralleled.

18. Rotation of phases:
Each generator set or system being paralleled must be connected so that all phases rotate in the same direction. If the phase rotation is not the same, no more than one phase can be synchronized.

19. Voltage match:
The voltage generated by sets or systems being paralleled must be within a small percentage of the same value. Usually 1 to 5 percent. The output voltage of a synchronous generator can be controlled by changing its excitation voltage. (This is normally done by the voltage regulator).
If two synchronous generators of unequal voltage are paralleled, the combined voltage will have value different from the voltage generated by either of the generators.
If, on the other hand, a synchronous generator is paralleled to a larger system such as a utility, a difference in voltages before paralleling will not change the voltage of the bus.

20. Frequency match:
The frequency of the oncoming generator must be very nearly the same as the system it is being paralleled with, usually within 0.2 percent.
With synchronous oncoming generator this match is normally accomplished by controlling the speed of the prime mover driving the oncoming generator.

21. Phase angle match:
The phase relationship between the voltages of the systems to be paralleled must be very close prior to paralleling. This match usually is within plus or minus 10 degrees. The phase matching, like frequency matching, is accomplished by controlling the speed of the oncoming generator’s prime mover.

22. Parallel Operation of Alternators
100%
speed
ISOCHRONOUS OPERATION:
It may be represented by a family of horizontal lines, each line representing a speed setting. If set to maintain the speed represented by line A, and connected to an increasing nonsynchronous load, the speed would vary as follows. Beginning with no load, the speed will remain constant at A as load is increased until the capacity of the engine is reached.
Therefore, the generator in the isochronous mode will operate at the same set speed/frequency regardless of the load it is supplying up to its full load capabilities.
This mode can be used on one generator set running by itself in an isolated system.
Load
100%

23. With droop the speed decreases with load
DROOP SYSTEM 63 60
speed 57
Droop is a decrease in speed or frequency, proportional to load. That is, as the load increases, the speed or frequency decreases. Droop is expressed as the percentage reduction in speed that occurs when the generator is fully loaded. With a given droop setting, a generator set will always produce the same power output at a particular speed or frequency.
If all generators sets in a droop system have the same droop setting, they will each share load proportionally. The amount of load will depend on their speed settings. If the system load changes, the system frequency will also change. A change in speed setting will then be required to offset the change in feedback and return the system to its original speed/frequency. In order for each generator set in the system to maintain the same proportion of the shared load, each generator will require the same speed change.
50%
Load
100%
With droop the speed decreases with load

24. Parallel Operation of AlternatorsC B
100% 4%
speed A
SPEED DROOP:
It may be represented by a family of lines that have slope, each line representing a speed setting. Similarly loaded the speed drop down as load increase. Suppose now that load limit is set at 50%. The behavior is the same as before except that now the speed drops from the setting line until the 50% load condition is reached.. Assume the speed droop governed machine is connected to a synchronous system so large that our engine cannot affect its frequency (an infinite bus). Now we must remember that the speed of the engine is no longer determined by the speed setting, but rather by the frequency of the bus. What is accomplished by a change in speed setting in this case is a change in load, not in speed.
If we have a setting A for which the no load speed is equal to bus speed (or frequency) in order to synchronize. Once on the line, if we increase speed setting to B we do not change speed but we pick up approximately ½ load. Further increase in setting to line C will fully load the engine. If regulation as indicated by slope of lines, is 4%, and the alternator is disconnected from the bus while carrying ½ load, the free engine will go up in steady-state speed 2%. If set on line C, carrying full load and similarly disconnected, the no load speed would be 4% above synchronous.
50%
Load
100%

25. Parallel Operation of AlternatorsB
100% F3
speed F2 F1 A
SPEED DROOP:
In case if two identical units having speed droop governors are paralleled with each other and there are no other generating units in the system, the frequency will be determined by the speed settings of the governors, the regulation of the governor-engine combination and the total load on the system. Here, as before, it must be remembered that the actual speeds of both units must be identical even though their speed settings may be different.
Assume both units to be set on curve A, and the total load equal to the capacity of one unit. That is 100%.
In this case each engine carries 50% and the speed is that of line f1, being the same for both units. Suppose now that one unit is set at B, the other remaining at A. The speed at which both units can run and carry a total of 100% load is now f2, and the load is unequally divided, 75% to the unit with the higher setting, 25% to the lower. The increase in system speed however is by no means as great as the increase in speed setting of B.
If now, with settings A and B, the load is increased to 150%, the regulation being the same for both units. The additional 50% will be divided equally between them and A will again carry 50% while B carries 100%. The speed of the system will again be back to f1. Further increase, however, will overload B, so the effective capacity of the system is only 150% instead of the 200% it would have if the speed settings were identical. If the load were dropped to 50%, it would all be carried by B and A would be unloaded with system frequency at f3.
25%
50%
75%
100%
Load

26. Droop / Isochronous
If multiple generator sets operate in parallel in an isolated system, operate only one generator in an isochronous and all other generators in a droop mode.
The Isochronus generator is a swing unit
The isochronous mode can also be used on generator set running in parallel with other generator sets. However, unless the governors are load sharing and speed controls, no more than one of the generator sets running in parallel can be in the isochronous mode. If two generator sets operating in the isochronous mode without load sharing controls are tied together to the same load, one of the units will try to carry the entire load and the other will shed all of its load.
Droop/Isochronous combines both droop and isochronous modes in one. All generator sets in the system, except one, are operated in the droop mode. The one unit not in the droop is operated in the isochronous mode. It is known as the swing machine. In this mode, the droop machines will run at the speed/frequency of the isochronous unit. The droop and speed settings of each droop unit are adjusted so that it generates a set amount of power. the output power of the swing machine will change to follow changes in the load demand.
Maximum load for this type of system is limited to the combined output of the swing machine and the total set power of the droop machines. The minimum system load can not be allowed to decrease below the output set for the droop machines. If it does, the system frequency will change, and the swing machine can be motorized.
The machine with the highest output capacity should be operated as the swing machine, so that the system will accept the largest load changes within its capabilities.

27. 2301 Electric Governor Bus ENGINE GEN Magnetic Pickup 3 ph PT 3 PH CT
Actuator
2301 Load sharing & speed control
WOODWAR 2301 Electric Governor Operation:
The engine speed is felt by a magnetic pickup. This pickup makes an AC voltage that is sent to 2301 Control. The control box sends DC voltage signal to the actuator.
The actuator changes the electrical input from 2301 control to a mechanical output that is connected to the fuel system by linkage.
For example, if the engine speed is more than the speed setting, the 2301 control will decrease its output and the actuator will now move the linkage to decrease the fuel to the engine.
Note that the engine speed frequency signal (AC) is sent to the 2301 control box where a conversion is made to DC voltage. The DC signal is now sent to control the actuator, and this voltage is inversely proportional to engine speed. This means thatif engine speed increases, the voltage output to the actuator decreases. When the engine speed decreases, the voltage output to the actuator increases.
DC Power 20 – 40 V DC
Parallel lines

28. 2301 Load Sharing Control Box
parallel control box has two functions: precision engine speed control and kilowatt load sharing. The system measures engine speed constantly, then it makes the necessary corrections to the engine fuel setting through an actuator connected to the fuel system.
- The rated and low idle engine speeds are set with speed setting potentiometers.
The ramp time potentiometer controls the amount of time it takes the engine to go from low idle to rated speed.
The gain and stability potentiometers control the response of the engine to a change in load. The gain potentiometer is used to decrease response time to minimum. The stability potentiometer is used to get the best speed stability for the gain setting that is used.
The speed droop potentiometer controls the amount of speed droop. It can be set between 0 and 13% droop. Droop is necessary when paralleling with a utility bus.
Load gain potentiometer is set so that the ratio between the actual kilowatt output and the rated kilowatt output of each unit in the system is the same.
The speed failsafe circuit will stop all voltage output to the actuator if the magnetic pickup signal has a failure. This will cause the actuator to move to FUEL OFF position.