There are three adjustment parameters that control the response characteristics of the fuel actuator and the wastegate actuator. The following adjustment parameters are used to control the response characteristics:
- GAIN
- STABILITY
- COMPENSATION
These adjustments are provided in order to obtain the optimum actuator response characteristics to load and speed changes while providing a stable operation at steady state conditions.
The function of the gain adjustments and stability adjustments are to optimize the response characteristics of the actuator. The gain adjustment controls how fast the actuator will respond to load and speed changes. Increasing the gain adjustment provides faster response to load and speed changes. Decreasing the gain adjustment will slow down the actuators response to the load and the speed changes. The stability adjustment dampens the actuators response characteristics to load and speed changes. Increasing the stability adjustment provides less dampening during load changes. Decreasing the stability adjustment provides more dampening.
To properly set the actuator dynamics, increase the gain setting until the actuator becomes unstable. Slowly decrease the gain setting as necessary to stabilize the actuator. Bump the engine by pressing the 6 key on the DDT. Pressing the 6 key while in DDT screens 70, 71 and 72 for the fuel actuator or 80, 81 and 82 for the wastegate actuator will cause the fuel actuator to open and close very quickly. This will force a speed offset on the engine to document how well the settings respond to change. Observe that the engine returns to the proper setting with little overshoot or undershoot. To reduce overshoot, decrease the stability adjustment. To reduce undershoot, increase the stability adjustment.
Note: Increasing the stability setting may require decreasing the gain setting in order to maintain a stable operation.
Decrease the compensation adjustment until a slow, periodic instability is observed. Then slightly increase the compensation adjustment. Repeat the gain and stability adjustments. Continue to increase the compensation adjustment and readjust the gain and stability adjustments until stability is achieved and the engine's response to load and speed changes is optimized.
For G3600 engines, that are used in Generator Set applications, there are two sets of fuel actuator response characteristics that are programmed into the personality module. One set of response characteristics is used to provide "off grid" engine stability for synchronization. Another set of response characteristics is for "on grid" stability. Any adjustments to the settings for the fuel actuator through the DDT will apply to both the "off grid" and the "on grid" response characteristics.
For G3600 Engines used in industrial applications, the recommendation is that initial governor adjustments for gain, stability and compensation are adjusted to "-15" settings.
Fuel Actuator Gain Adjustment Procedure
- Press the "SELECT MODE" button on the DDT in order to display the "GOV GAINS" screen number "07" .
- Press the "SELECT FUNCTION" button in order to display the "GOV GAINS" screen number "70" .
- Press the "ALT2" button in order to increase the governor gain offset. Press the "ALT1" button in order to decrease the governor gain offset.
- Adjust the governor gain offset in order to obtain the most stable engine operation.
- The governor gain offset can be returned to the factory preset "0" value by pressing the "0" button on the DDT.
Note: Adjustments to the "GAIN" value have a direct affect on the speed of the response signal that is sent to the fuel actuator whenever there is a difference between the desired rpm and the actual rpm. Excessive increase in the "GAIN" offset may amplify engine instability.
Fuel Actuator Stability Adjustment Procedure
- Press the "SELECT MODE" button on the DDT to display "GOV GAINS" screen number "07" .
- Press the "SELECT FUNCTION" button in order to display "GOV STAB" screen number "71" .
- Press the "ALT2" button in order to increase the governor stability offset. Press the "ALT1" button to decrease the governor stability offset.
- Adjust the governor stability offset in order to obtain the most stable engine operation.
- The governor stability offset can be returned to the factory preset "0" value by pressing the "0" button on the DDT.
Note: Adjustments to the "STAB" value has an affect on the dampening of the command signal that is sent to the fuel actuator. Excessive increase in the "COMP" offset may cause the amplitude of the high frequency instability to increase.
Fuel Actuator Compensation Adjustment Procedure
- Press the "SELECT MODE" button on the DDT in order to display "GOV GAINS" screen number "07" .
- Press the "SELECT FUNCTION" button in order to display "GOV COMP" screen number "72" .
- Press the "ALT2" button to increase the governor compensation offset. Press the "ALT1" button in order to decrease the governor compensation offset.
- Adjust the governor compensation offset in order to obtain the most stable engine operation.
- The governor compensation offset can be returned to the factory preset "0" value by pressing the "0" button on the DDT.
Note: Adjustments to the "COMP" value will have an affect on "slow hunting" stability characteristic and the amount of overshoot after a disturbance.
Note: In order to prevent the zeroing out any adjustments that have been made, always use the "SELECT MODE" key to exit the screen numbers "70", "71" and "72" .
Exhaust Bypass (Wastegate) Group
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| Illustration 1 | g00481880 |
(1) Wastegate plate. (2) Rod and rod ends. (3) Actuator. (4) Pointer. | |
Procedure To Assemble And Adjust The Exhaust Bypass Linkage:
- Assemble wastegate plate to the shaft, leaving the mounting bolts loose.
- Assemble and install the axial stop assembly, the washer and the cover.
- Hold the wastegate plate in the fully closed position. Tighten the mounting bolts to a torque of 14 ± 3 N·m (10 ± 2 lb ft) .
- Assemble the split clamp on the shaft.
Assemble the split clamp on the shaft at the following distance from the edge of the exhaust bypass elbow housing. ... 6.0 ± 1.0 mm (.24 ± .04 inch)
- Install the levers (keyed) on the wastegate shaft and the wastegate end of the cross shaft.
- Provide equal thread engagement of the rod ends on the adjustable rod. Adjust the upper connecting rod to a length of 143.5 ± 1.5 mm (5.65 ± .06 inch) .
- Install the rod and the rod ends. Adjust the length so that the cross shaft lever is at an angle of 45.0 ± 1.5 degrees. The angle should be counterclockwise from the horizontal centerline of the cross shaft, when the wastegate is held in the fully closed position.
- Tighten the nuts to a torque of 25 ± 6 N·m (18 ± 4 lb ft) .
- Install the lever (keyed) on the actuator end of the cross shaft.
- Providing equal thread engagement of the rod ends on the adjustable rod. Adjust the rod between the cross shaft and the actuator to a length of 148.5 ± 1.5 mm (5.85 ± .06 inch) .
- Install the actuator lever (splined) on the actuator shaft. Adjust the rod length so that the lever is at an angle of 40.0 ± 1.25 degrees from the vertical centerline of the actuator shaft when the wastegate is held in the fully closed position.
Note: The pointer of the actuator should point at the zero position. The pointer should touch the internal stop of the actuator.
- Move the wastegate to the fully open position. Check that the actuator is against the internal stop. Check that the pointer on the actuator points at the 100 percent position.
Note: The wastegate plate is mounted offset on the shaft. In the fully open position, the upper part of the plate must not be more than horizontal. Adjust the length of the rod between the wastegate and the cross shaft in order to prevent the plate from being more than horizontal.
- Tighten the nuts to a torque of 25 ± 6 N·m (18 ± 4 lb ft) .