Sparky
Member
I'm having a problem with two PID's that seam to work, both together (resulting in a massive over shot) and against each other (resulting in an inability to reach set point). I remember hearing something about cascading. Where two PIDs could work inter related. Here is some bkgrnd on the PIDs:
1. Controls pressure via a control dampener for an outlet fan. Set point -.5 inH2O out let fan is not on a drive and is on 100%
2. Controls temperature via a gas burner fed by a fan on a VSD.
The fan is controlled in manual, no PID yet, until I can stabilize the temp/pressure.
Since temp and pressure correlate with each other it is very difficult to stabilize either variable.
Any info on how to cascade PIDs or any thing else, would be great.
Any questions of spacifics just ask.
1. Controls pressure via a control dampener for an outlet fan. Set point -.5 inH2O out let fan is not on a drive and is on 100%
2. Controls temperature via a gas burner fed by a fan on a VSD.
The fan is controlled in manual, no PID yet, until I can stabilize the temp/pressure.
Since temp and pressure correlate with each other it is very difficult to stabilize either variable.
Any info on how to cascade PIDs or any thing else, would be great.
Any questions of spacifics just ask.