Carotron PI240-000, Instruction Manual

Page: 16 / 22

16
5.4 General PI Adjustment Procedure
The following is a generic procedure for setting up the PI module.
Step 1: Select Output Type
1. Select the type of output desired using Jumper J2. If a Voltage output is desired,
select V on J2 and use output terminals 7 (OUTPUT) and 8 (VOLTAGE
RETURN). If a Current output is desired, select I on J2 and use output terminals 7
(OUTPUT) and 9 (CURRENT RETURN).
Step 2: Connections
1. Make connections per drawing C13703 on page 19. Initially, there should be no
connection on the Teach input on terminal 12.
Step 3: Initial Setup
1. Set Prop Gain potentiometer fully counter clockwise. Set all other potentiometers
to 8 turns clockwise. If the current positions are unknown or in doubt, rotate
potentiometer counter clockwise 20 turns, then clockwise 8 turns.
Step 4: Teach Process Variable (Feedback)
1. The order in which the two extreme feedback levels (minimum and maximum) are
taught determines the logic of the control loop.
2. Apply the feedback signal level (either minimum or maximum) to terminal 4 that
should cause the output to increase. Apply power to the module and within one
minute, connect the Teach input (terminal 12) to circuit common (terminal 11).
3. Apply the other extreme feedback signal level (either minimum or maximum) to
terminal 4 and disconnect the Teach input (terminal 12) from circuit common
(terminal 11).
Step 5: Select Unipolar or Bipolar
1. If bipolar operation is desired, wait at least one minute after the unit has been
powered and place a jumper from the Teach input (terminal 12) to circuit common
(terminal 11). No connection on terminal 12 selects unipolar.
Step 6: PI Trim
1. Manually force the feedback sensor so it is in the “increase output” state. Enable
the PI loop by closing the contact across terminals 10 & 11.
2. Verify that the module output signal increases.
3. Likewise, manually force the feedback sensor so it is in the “decrease output”
state and verify that the output decreases.
4. If the module exhibits opposite logic (i.e. increases speed when it should decrease
speed), then repeat Step 4 teaching the feedback levels in the opposite order.
5. Wait until the PI output saturates (stops increasing or decreasing) and adjust the
PI Trim potentiometer until the desired output level is achieved.
Step 7: Tune
1. Set Prop Gain potentiometer approx 8 turns clockwise.
2. Any signal applied to the Summing Input (terminal 5) will sum with the PI signal and
output on terminal 7.
3. If necessary, adjust the Prop Gain and Integral Time potentiometers if any
instability is noticed or response time is sluggish.