Watlow ez-zone pm - Page 228

Watlow EZ-ZONE
®
PMI Controller • 224 • Chapter 10 Applications
Denitions:
- Current Position is an approximation of the valve's position as it relates to a power level (0 -
100%) where 0% is fully closed and 100% is fully open.
- Dead Time is the minimum on time that the valve will travel once it is turned on in either the
closed or open direction. Dead Time = Valve Dead Band / 100 * Valve Travel Time.
- Valve Travel Time is the amount of time the valve needs to be turned on (either open or close)
to eliminate the error between the estimated valve position and the desired power level. A posi-
tive On Time value indicates the need to open the valve while a negative value indicates the
need to close the valve. On Time = (Input 1 Value - Current Position) / 100 * Valve Travel Time
When power is applied to the controller, the valve is closed and time is set to 0.
- Special Output Function 1 is the close signal to the valve.
- Special Output Function 2 is the open signal to the valve