defcon.klaxon
Lifetime Supporting Member
Hi guys,
I'm working on a well pump that is supposed to use a PID loop to maintain system pressure through changing pump speed. I'm using a SCADAPack 350 for the PLC and I'm having a bear of a time getting the PIDA instruction to work properly.
Some basic background on the function: when the pump is called to run, I have the pump ramp up to a manual speed setpoint (80%), which holds for 10 seconds. Then once the ten seconds is up, the PIDA goes into automatic mode and starts controlling pump speed.
I've started by trying to tune the loop with just Proportional Gain, but the output doesn't seem to want to react at all. The 80% start point does get sent to the VFD, but once the PIDA block goes from manual to automatic, the equation never seems to change the output. Also, when the PIDA block is not enabled, the output seems to stay at whatever last value there was; I guess I assumed if the PID block was disabled the output would go to 0 but maybe the PID block needs a ton of support code to take care of all these situations? At this point I feel pretty darn lost at just what it takes to implement PID loops in TelePACE.
I've looked around for examples in TelePACE and am quite surprised to not find much. At this point I don't know how far off I am; I'm going to keep trying to figure this out but if anyone has some experience with how to get things properly configured I'd certainly appreciate some guidance.
I'm working on a well pump that is supposed to use a PID loop to maintain system pressure through changing pump speed. I'm using a SCADAPack 350 for the PLC and I'm having a bear of a time getting the PIDA instruction to work properly.
Some basic background on the function: when the pump is called to run, I have the pump ramp up to a manual speed setpoint (80%), which holds for 10 seconds. Then once the ten seconds is up, the PIDA goes into automatic mode and starts controlling pump speed.
I've started by trying to tune the loop with just Proportional Gain, but the output doesn't seem to want to react at all. The 80% start point does get sent to the VFD, but once the PIDA block goes from manual to automatic, the equation never seems to change the output. Also, when the PIDA block is not enabled, the output seems to stay at whatever last value there was; I guess I assumed if the PID block was disabled the output would go to 0 but maybe the PID block needs a ton of support code to take care of all these situations? At this point I feel pretty darn lost at just what it takes to implement PID loops in TelePACE.
I've looked around for examples in TelePACE and am quite surprised to not find much. At this point I don't know how far off I am; I'm going to keep trying to figure this out but if anyone has some experience with how to get things properly configured I'd certainly appreciate some guidance.
