controls

We have a project coming up where we are going to control and record the temperature of six autoclave. The temperature will be from ambient to 275 F. A manual pressure regulated valve controls temp. So the plc will only turn a steam valve on and off and time the proccess. We plan to use thermocouples to get this temp. into plc. Plc will be slick 5/03 with a panelview 550 dh 485 and probabaly rsview 32 on office pc. Any ideas thoughts suggestions will be appreciated.

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Steam Control

What exactly are you looking for?

If you are looking for logic to turn the control valves on and off, you can just use compare block for the control valves.

Temperature < Setpoint - Breakpoint, turn on valve
Ex: Breakpoint = 2

I use this logic to control temperature in a machine. We also have a dump valve to add cold water to cool it back down if the temperature goes over setpoint.

Temperature > Setpoint + Breakpoint, turn on dump valve.

My temperature application is not to critical, we just need to stay around setpoint.

If you need it real critical, you may want to consider a PID Block.

In the one autoclave control I'm familiar with, the thermocouples are wired to a chart recorder and aren't part of the control. They use pressure switches to control the steam valves.

After the product is loaded into the autoclave, the PLC controls several timed pressurize/purge cycles to get the product up to temperature. Then it goes into the primary cycle where the pressure switch takes over.

There are a couple of standard cycles programmed into the PLC which the operator selects by means of switches. I've talked to the owner about adding an HMI to allow the operator to set times or adding analog or thermocouple modules to the PLC to allow the operator to control temperature or pressure, but they don't see any benefit.

thoughts

Steve
We have 5 big autocaves (chambers) the way you explained is quite similar to the way they work. We did what you suggested to your customer. We have Honeywell Controllers and Honeywell chart recorders the Honeywell controller is where the reciepes (PID PROGRAMS) are stored. The thermocouple input comes to the Honeywell and controls a modulated steam valve to control temparature. It had a second analog out and we used it as a signal to a 5/03 which controls the hydrolic and air part of the process. Now we can see the whole process in the office the temp.,ram pressure, and all digital inputs. At the present we view this with excel and rslinx (poor people have poor ways). The other autoclaves in the first of this post are completely manual. Now I realize probably no else has this problem, but every now and then the operators don`t run them as they should. So we plan to automate them (partly). The pressure regulated steam valve will still control the temp., let plc control steam on, air and cure time.
Mark

What exactly are you looking for?

Click to expand...

Ideas on whither Slick 5/03 with thermo, anl, and digital cards and PV 550 HMI and RSveiw in office pc to store records of cures is the best way to achive this. We have a DH485 net work going by this area (question) Will rsview 32 overload it? Stuff like this

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