Application of Set Point Tracking Facility in PID Controllers

[Papps]

I understand the function of Set Point Tracking Facility in PID controllers.

I want to know the application of these ...I.e where it is applicable and to which control loop it can be used effectively.

 

[controlnovice]

Setpoint tracking can be used in any controller.

Main reason to use setpoint tracking is to minimize a bump in control:
if someone places the controller in Manual mode, the target Setpoint (SP) will track, or follow, the Process Value (PV). So, in Manual mode, the controller output might be 40% with a PV of 238 kPa...the SP will also be 238 kPa. When setting the controller back to Automatic mode, the SP and PV will be equal, so there will be no 'bump' in controller output.

Imagine if setpoint tracking were turned off, and your setpoint was 1500 kPa. The moment you switch back to Automatic mode, the PV is 238 and the setpoint is 1500, so your output will make a very large jump (depending on tuning of course).

Sometimes setpoint tracking is turned off to help maintain the original SP. If the controller is placed in Manual, it's possible the original setpoint could be lost if setpoint tracking were turned on. So, in some control processes, it's more important to keep the original setpoint than reduce the bump in output.

In the end, it's up to the user to determine the behaviour of the control.

______________________________________________________________________________
This is normally the space where people post something insightful.

 

[Papps]

Thanks for the reply....

I understand the function. Would like to have clarity on the application of this function.It may not be best applicable when used in split range control system rather than a feed back controller.

 

[danw2]

Your split range control does not use auto/manual?