West Control Solutions Pro-EC44 - Manual (Page 113)

Pro-EC44 2-Loop Graphical Profile Controller & Recorder
Pro-EC44 Product Manual - 59540-1 October 2013 Page 106
Fine Tuning
Small adjustments can be made to correct minor control problems. These examples assume
reverse acting control (e.g. heating). Adjust accordingly for direct action. If they do not help
solve the problem, re-tune the controller as detailed on the preceding sections.
Note: When fine tuning the settings, only adjust one parameter at a time, and
allow enough time for the process to settle into its new state each time you
change a value.
Cycle Times
A separate cycle time adjustment parameter is provided for the Primary and Secondary
control when using time-proportioning control outputs.
If the process oscillates at the same frequency as the cycle time, it indicates it may be too
long for the process. Decrease the cycle time and re-check the period of oscillation, if it has
changed to match the new cycle time this confirms that the time is too long.
If the control actuators will accept it, continue reducing the cycle time until the process
stabilises, or no further improvement is seem.
Recommended times. Relays ≥10 seconds. SSR Driver 1 second.
Proportional Cycle Times
Ideal: Stable Process Too Long: Oscillation period = cycle time.
Note: Adjusting the cycle time affects the controllers operation; a shorter cycle
time gives more accurate control, but mechanical control actuators such as
relays will have a reduced life span.
Proportional Bands
Increase the width of the proportional bands if the process overshoots or oscillates
excessively. Decrease the width of the proportional band if the process responds slowly or
fails to reach setpoint.
Proportional Bands
Too Narrow: Process Oscillates Too Wide: Slow warm up and response