50
Digital Position-Proportional Controllers
E5EZ-PRR
■
Adjustment
For adjustments to PID, please execute AT.
■
Fixed
Settings
for
Position
Proportional
Control
After selecting position proportional control, it is possible to use closed/ floating,
electro-mechanical calibration, travel time, position proportional dead band,
switch hysteresis, potentiometer input error, and process value dead band.
• Closed/ Floating
•
Closed Control
Connect the potentiometer to perform valve opening feedback control.
•
Floating Control
Control in which no feedback is provided by a potentiometer on the valve's
opening, so that control can be performed without a potentiometer.
• Electro-Mechanical
Calibration and
Travel Time
Just like in closed control, or in floating control where a valve's opening is to be
monitored, electro-mechanical calibration is to be performed when a potentiom-
eter is connected. The valve's travel time, from being completely open to being
completely closed, is also set for self-measuring.
In cases of floating control where a potentiometer is not connected, it will be nec-
essary to manually set the travel time. Set the time required for the valve to go
from complete openness to complete closure under travel time.
• Position Proportion Dead
Band Switch and Position
Proportional Hysteresis
The valve output period (the time it takes the OPEN output and CLOSE output
switch to go from ON to OFF) is set as the position proportional dead band, and
hysteresis is set as switch hysteresis.
Its relationship with the extent of the valve's opening is as shown below:
• PV Dead Band
When the process value is within the PV dead band, control is controlled accord-
ing to the logic that the process value = set value. This function is meant to pre-
vent unnecessary output in cases where the process value approaches the set
value.
• Potentiometer Input Error
When the potentiometer produces an error during closed control, this is a func-
tion that chooses to stop control or switch to floating control, allowing control to
continue.
-100%
OFF
ON
0
MV-Extent of Opening 100%
Switch position proportional hysteresis
Dead Band
