Closed loop pressure control

JeffKiper

Lifetime Supporting Member + Moderator
Join Date
Jun 2006
Location
Indiana
Posts
2,447
I have just received a RFQ for a closed loop pumping system (hydroforming ).
I did a small system like this about 8 years ago in a SLC. It worked but I didn't like the outcome.I am looking at using a CompactLogix and 525.

So what are the advantages of doing the control each way? In the PLC it has full control over the system and the drive would have very little programming in it. In the drive it would have a setpoint send over from the plc.
 
I am assuming by each way you mean control start/stop/speed in the drive or via commands from the PLC.

You have a lot of versatility just using the 525 and sending start, stop, and set point to it. If you are using the ethernet you can set up datalinks to handle your PID gains, set point, and process value. I have had trouble commissioning drives with data links configured via the keypad. It seems the best way is to do this with a laptop, meaning if this is a remote site it will be more difficult to support.

Using the PLC you have all of your programming in one spot and don't need to message the VFD to change gains, set points, or read back the process value. If you use digital and analog outs you don't have to worry about drive profiles matching the drive or even having to use the same drive.

The list goes on. I would say give the drive control a chance. I would be surprised if most here would not say to keep control within the PLC.
 
Hey Jeff. Long time.

If all you are doing is the pressure control you might want to talk to Peter Nachtwey. That would probably be a more appropriate tool for the job and wouldn't be any more expensive. If you have a ton of additional I/O to control then that may not be the best option.

I've just had my first swing at the PF525 and am not overly impressed. I suppose you get what you pay for but the step down in performance from the PF750 series caught me by surprise.

I know this is a little old school but if you want the "best of both worlds" you might want to consider a PF700S with DriveLogix. Not DeviceLogix, but DriveLogix. That would give you a full-blown Logix development environment, including the capability to control Ethernet/IP remote I/O, directly on the drive. That removes some of the communication latency.

Keith
 
Have never heard of hydroforming, so googled it.. Is pretty cool. Assuming you are driving the pressure pump with the 525 ?? What sort of pump is it ??

If the process is a simple pressure PID tune, guess there is no reason not to just use the VSD. If there are steps involved, (prefill, pressure stage, dwell...), and / or you have ancillary controls to handle, guess a PLC would be more suitable. Don't know if I would immediately step into a compact thou.. A 1400 would have plenty of capability..
 
Last edited:

Similar Topics

Hi Guys, During PID Tuning by Ziegler Nichols Closed-loop method, In TIA Portal there is a Trend Tool used to determine Ultimate Period; marking...
Replies
9
Views
1,820
So it looks like i am stuck with an old reliance DC drive on this project instead of the powerflex dc w/ 22-COMM-E. That being said i am trying to...
Replies
0
Views
1,184
Hello, I am trying to make an Automatic Coolant Dispensing station for my client. This unit will be stationed next to a CNC Machine to monitor...
Replies
56
Views
14,394
We're implementing a second pump in a piece of equipment that pumps primarily water, or fluids similar to water. This pump is located in a stand...
Replies
23
Views
13,061
I have a project where I need to use a proportional valve to control hydraulic system. Before, I used open loop and now I try closed loop PID with...
Replies
3
Views
3,353
Back
Top Bottom