ChrisP
Member
We have a system that we are programming for a controlled paint booth environment. We are controlling temperature and humidity in the booth at various setpoints depending on the current function in the booth. We are using RSLogix 5000. There is a cooling section, reheat section, and humidifier section in the process.
The problem: We are controlling the chilled water valve to get the temperature down to a predefined point to control humidity. There is a considerable amount of overshoot, and the system won't stabilize like we'd like it to. I think one of the problems is that there is a considerable dead time or lag between the time when we make a valve change and when the temperature actually starts to change and then when the temp starts to change, it's inertia continues for a while after the valve is modified. I'd like to see the valve to start to change when temp is approaching the setpoint, not waiting until it has past the setpoint.
We don't work with this type of system very often and haven't had much experience with tuning PID's. Also, it isn't feasible for us to purchase RSTune or other software, since we are only doing this one time for the setup and then will be turning the system over to the client for maintenance. I'd appreciate any help that you guys could give.
The problem: We are controlling the chilled water valve to get the temperature down to a predefined point to control humidity. There is a considerable amount of overshoot, and the system won't stabilize like we'd like it to. I think one of the problems is that there is a considerable dead time or lag between the time when we make a valve change and when the temperature actually starts to change and then when the temp starts to change, it's inertia continues for a while after the valve is modified. I'd like to see the valve to start to change when temp is approaching the setpoint, not waiting until it has past the setpoint.
We don't work with this type of system very often and haven't had much experience with tuning PID's. Also, it isn't feasible for us to purchase RSTune or other software, since we are only doing this one time for the setup and then will be turning the system over to the client for maintenance. I'd appreciate any help that you guys could give.