- "Governor Gain Factor"
- "Governor Stability Factor"
- "Governor Compensation Factor"
Gain - Gain determines the speed of the control's response in adjusting for the difference between the desired condition and the actual condition. Increasing the gain provides a faster response to the difference between the desired condition and the actual condition.
Stability - Stability controls the speed for elimination of the error in the difference between the desired condition and the actual condition. The stability dampens the response to the error. Increasing the stability provides less damping.
Compensation - Compensation is used to adjust the time delay between the control signal and the movement of the actuator. If the compensation is too low, the engine speed will slowly hunt. If the compensation is too high, the engine speed will rapidly fluctuate.
Note: The default value for these parameters is "0". The default values should be sufficient for initial start-up. However, the values may not provide optimum performance.
These adjustments are provided in order to obtain optimum responses to changes in the engine's load and in the engine's speed. The adjustments also provide stability during steady state operation.
If you have a problem with instability, always investigate other causes before you adjust the governor. For example, diagnostic codes and unstable gas pressure can cause instability.
When you adjust the governor, make sure that the "Grid Status" parameter is "Off".
To change the "Governor Gain Factor" or the "Governor Stability Factor" , use the "Real Time Graphing" feature on the "Information" drop-down menu of Cat ET. The graph provides the best method for observing the effects of your adjustments.
After you make adjustments, always test the stability by interrupting the engine speed and/or load. Operate the engine through the entire range of speeds and of loads in order to ensure stability.
Note: Adjustment of the "Governor Gain Factor" directly affects the speed of the throttle actuator when there is a difference between the actual engine speed and the desired engine speed. An excessive increase of the "Governor Gain Factor" may amplify instability.
To set the "Governor Gain Factor", increase the value until the actuator becomes unstable. Slowly reduce the value in order to stabilize the actuator. Observe that the engine operates properly with little overshoot or undershoot.
Adjustment of "Governor Stability Factor" dampens the actuator's response to changes in load and in speed. Increasing the value provides less damping. Decreasing the value provides more damping. To reduce overshoot, decrease the value. To reduce undershoot, increase the value.
Note: An increase of the "Governor Stabillity Factor" may require a decrease of the "Governor Gain Factor" in order to maintain engine stability.
Illustration 1 shows some typical curves for transient responses.
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| Illustration 1 | g01017530 |
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Typical curves for transient responses (Y) Engine speed (X) Time (1) The "Governor Gain Factor" is too high and the "Governor Stabillity Factor" is too low. There is a large overshoot on start-up and there are secondary overshoots on transient loads. (2) The "Governor Gain Factor" is slightly high and the "Governor Stabillity Factor" is slightly low. There is a slight overshoot on start-up but the response to transient loads is optimum. (3) The "Governor Gain Factor" is slightly low and the "Governor Stabillity Factor" is slightly high. There is optimum performance on start-up but slow response for transient loads. (4) The "Governor Gain Factor" is too low and the "Governor Stabillity Factor" is too high. The response for transient loads is too slow. (5) The response to transient loads is adjusted for optimum performance. | |
The default value of the "Governor Compensation Factor" is acceptable for most applications. Do not adjust the "Governor Compensation Factor" unless the engine's response to changes in load is unacceptable.
Decrease the "Governor Compensation Factor" until a slow, periodic instability is observed. Then, slightly increase the value. Repeat the adjustments of the "Governor Gain Factor" and of the "Governor Stability Factor". Continue to increase the "Governor Compensation Factor" and readjust the "Governor Gain Factor" and the "Governor Stability Factor" until stability is achieved and the engine's response to changes in load and in speed is optimized.
Illustration 2 is a graphic representation of adjusting the "Governor Compensation Factor".
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| Illustration 2 | g01017541 |
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The increased width of the line for the actuator voltage indicates that the throttle actuator is more active as the value of the "Governor Compensation Factor" is increased. (Y) Actuator voltage (X) Time in seconds | |