The desired flow rate is 1040 cubic meters per hour. The flow meter output is 4-20mA represents 0-2000 cubic meters per hour. The engine governor is controlled by a Linak LA12 actuator, which gives an RPM range from 790 to 1760 under load.
Control Program Description
The USC701 application program consists of two cascaded control systems:
- A PID control system that compares the actual water flow in the pipe with the required flow. The PID controlled operates when the Auto switch is activated.
- A three state controller that sets a linear actuator using a 10k potentiometer feedback. When Manual mode the actuator travels to a percent position set by the access module. When in auto mode the PID controller controls the setting for the 3 state controller.
| Hot key | Description |
|---|---|
| UP | Display flow (CH1) |
| DOWN | Display set point to control to when in auto mode. |
| BACK | Display OUT% indicates the required output from the manual or PID control. |
| NEXT | Display ACTUATOR indicates actuator output position, when operating correctly this will be close to OUT%. |
| ENTER | Goes to trim menu to adjust required flow rate and Trim menu. |
3 State Controller Tuning
- Leave the main pump engine off and power up the control system including the USC701 and the linear actuator.
- Program the USC701 with the application UAP1076.
- Run the linear actuator to minimum speed setting and measure the voltage from the wiper on terminal 20 of the USC701.
- Move the linear actuator to maximum speed setting and measure the voltage from the wiper on terminal 20 of the USC701.
- Modify the calibration of USC701 CH2 so that it measures 0-100% for the requited actuator movement.
- Enter 50 in Con_G (Manual) the actuator should move to the middle position.
- The actuator may hunt backwards and forwards increase the value of Con_d (S3_DB%) until hunting stops.
- Enter 10 in Con_G (Manual) then enable manual mode, the actuator should move to about 10%.
- Enter 90 in Con_G (Manual) then enable manual mode, the actuator should move to about 90%.
- Repeat steps 6 to 9 until best dead band setting is found. NOTE If wishing to prevent the actuator from being driven into its stops offset the 0 and 100% positions away from the ends. To increase relay life the on and off delay times can be increased, this will introduce the need for increased dead band.
PID Tuning
- Refer to drawing "MA70317, Using The USC701 PID Wizard" listed under COA703 for tuning instructions.
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 uap1076a.usc = USC application program.
uap1076a.pdf = printable copy of application. |