Does anybody know how to set up the p.i.d for a turbine or vortex flow meter that controls a control valve in slc 500. The problem that I have is as soon as the setpoint is reached. My process variable drops off and the control valve shuts.Then it shoots back up to the setpoint, where it repeats the first step.Its basically a on and off operation.

 

Hi,
I don't know a specified PID tuning method for tribunes. But you can click address below in order to find information about tuning PID parameters for any system. This one is the most popular method "Ziegler-Nichols". it's basic and has got a wide range area to apply. But it's important to check your system's extremes. Also it could take long.

Good luck with your job...

"http://www.jashaw.com/pid/tutorial/":http://www.jashaw.com/pid/tutorial/

 

Also this could be usefull for you:

Steps
- Ensure that the process is "lined out" with the loop to be tuned in automatic with a gain low enough to prevent oscillation.
- Increase the gain in steps of one-half the previous gain. After each increase, if there is no oscillation change the setpoint slightly in order to trigger any oscillation.
- Adjust the gain so that the oscillation is sustained, that is, continues at the same amplitude. If the oscillation is increasing, decrease the gain slightly. If it is decreasing, increase the gain slightly.
- Make note of the gain which causes sustained oscillations and the period of oscillation. These are the "Ultimate Gain" (GU) and the "Ultimate Period" (PU) respectively.
- Calculate the tuning for the following set of equations. Use the set which corresponds with the desired configuration: P only, PI, or PID.

Tuning Equations
- P Only: Gain = 0.5 GU
- PI: Gain=0.45 GU, Reset=1.2/PU
- PID:Gain=0.6GU, Reset=2/PU, Derivative=PU/8

Good luck...