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Old November 8th, 2017, 09:32 PM   #1
travisroberts88
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Powerflex 525 PID Controll for a Pump in a Hot Water Set

I have a project coming up where I need to control the speed of my 5HP pump using a Powerflex 525 with a Pressure Sensor that is 4-20mA. What I am having difficulty with is setting up the PID Loop to control the pump speed where if it sees the 4mA it will run the pump faster to send more product through (In this application Hot water). and at 20mA the pump slows down in order to maintain a set point. I have an ifm electronic pressure sensor (PG2454 to be exact). At the moment I am running Pin 1 (brown) to +24vdc, pin 2 (white) to my 4-20mA IN on my 525, and 3 (blue) to +24common. on the 525 the terminals are 14 and 15 for the 4-20mA input and the common. I am not super familiar with the parameters in the Powerflex 525 to know what I need to set and to what value or if I am even on the right terminals. Any help would be greatly appreciated, PM if needed. The process is being heated with a Yokogawa controller for my heat set point. I have a closed loop of RO water that I am just using a set Hz rating on my first drive. I then add Well Water into the mix to go into the plant that needs to be maintained at 135F. This part is not the issue. I have the pressure sensor in and I cannot get the PID to control the Hz of the drive to adjust depending on the pressure. I need all the help I can get to try and get this to work. I am awful with PID as I don't fully understand how to tune it in in the first place in the 525 application. Thanks in advance!
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Old November 9th, 2017, 12:53 PM   #2
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For extra reference, I do not have a PLC in this system.
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Old November 9th, 2017, 02:13 PM   #3
RonJohn
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Welcome to the forum!

I have not done any PID programming in a PowerFlex drive before but glancing briefly at the PowerFlex 520-Series Adjustable Frequency AC Drive User Manual, Appendix F focuses on the PID setup. Looking at the bottom of p230, they mention adjusting parameters t095 & t096 for inverting the signal.

Hopefully this will get you started.
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Old November 9th, 2017, 02:15 PM   #4
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Quote:
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Welcome to the forum!

I have not done any PID programming in a PowerFlex drive before but glancing briefly at the PowerFlex 520-Series Adjustable Frequency AC Drive User Manual, Appendix F focuses on the PID setup. Looking at the bottom of p230, they mention adjusting parameters t095 & t096 for inverting the signal.

Hopefully this will get you started.
Yeah I read all over appendix F and still cant seem to get it right. Thanks for the try though!
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Old November 9th, 2017, 02:29 PM   #5
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I don't have time at the moment to dig deeper but a couple of quick thoughts:

1. If your analog input isn't wired right, all bets are off, so confirm this first. I'd think there's a parameter where you can see your analog input signal into the drive.

2. If you can't find it or still need to confirm wiring, get in touch with your local A-B rep and talk to their drives guy. That person can be a wealth of information and it's worth your while to develop a relationship with them. The A-B rep in Youngstown has a drives guy that has been a great go-to resource for the past 20 years.
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Old November 9th, 2017, 02:44 PM   #6
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Parameters 95,96, and 361 should be checked for the analog if you are using 4-20ma.

95 and 96 set your low and high, and 361 should show you what the drive has scaled the input to.

Parameter 460 should be set to 4-20 and then 383 should show what PID loop thinks the feedback is.
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Old November 9th, 2017, 02:57 PM   #7
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Quote:
Originally Posted by Dravik View Post
Parameters 95,96, and 361 should be checked for the analog if you are using 4-20ma.

95 and 96 set your low and high, and 361 should show you what the drive has scaled the input to.

Parameter 460 should be set to 4-20 and then 383 should show what PID loop thinks the feedback is.
I'm going to double check these now, thanks Dravik, will keep posted.
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Old November 9th, 2017, 03:31 PM   #8
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You'll also need to set the PID setpoint(465), which is a %, same range as you've scaled the feedback too.
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Old November 9th, 2017, 04:04 PM   #9
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You'll also need to set the PID setpoint(465), which is a %, same range as you've scaled the feedback too.
I must be doing something simple wrong. I use appendix F and follow the set up procedures and nothing works. My parameters are as follows:

P047 (Speed Reference 1) 11 (PID1 Output)
A459 (PID 1 Ref Sel) is on 0 (PID Setpoint)
A460 (PID 1 Fdback Sel) is on 1 (4-20mA Input)
A464 (PID 1 Setpoint) is at 70 (This may be part of my issue, I want to maintain around 70psi on my Pressure Sensor [IFM Electronic Part No. PG2454] and I want the pump to run slower if it is around the 70psi or higher and run faster if it drops below 70psi. So 20mA pump runs virtually nothing to drop the pressure down, and 4mA the pump runs around 60Hz.)
A467 (PID 1 Invert Err) is set to 1 (So the Analog Input is inverted in relationship, if I did this right.)
I do have A544 Disabled so it does not reverse my pump as it is on a 2-Wire selector switch control.
A458 (PID 1 Trim Sel) is set to 0 (Per an AB set up sheet I found)
t095 (Anlg In 4-20mA Lo) is set to 100%
t096 (Anlg In 4020mA Hi) is set to 0%
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Old November 9th, 2017, 04:11 PM   #10
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So, what's the output of the pressure sensor look like? Are you seeing a feedback from the analog input @ 361?
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Old November 9th, 2017, 04:17 PM   #11
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Quote:
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So, what's the output of the pressure sensor look like? Are you seeing a feedback from the analog input @ 361?

http://www.ifm.com/mounting/706086UK.pdf
Image should have uploaded also.If I monitor 361 while I have the pump on I have the 100% and even with a 4-20mA meter I can monitor right off the sensor. I also can source the 4-20mA and I only change states at 4mA and 12-16mA but it is either all or nothing. 0Hz or 60Hz no in between. Pins on standard Euro are 1 (Brn) to +24vdc 2(Blk) to 4-20mA In on drive (TB 15) and 3 (Blue) To DC common along with TB 14 to DC common.
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Old November 10th, 2017, 08:32 AM   #12
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Alright, fresh this morning. I would probably start trying to get this to work by setting the loop integral to 0(462), loop diff to 0(463) and the proportional to say 1(461).


Then, simulate your 4-20 input w/ something you can control. Start it at 15ma or so and make sure the Drive is reporting back a feedback of somewhere near 70% on parameter 361. Raise it up and down and verify you see the feedback into the drive vary properly.

Vary your setpoint and see if the drive ramps up or down to accommodate.
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Old November 10th, 2017, 11:00 AM   #13
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Hey all, just and update. I got it working last night finally! Was able to actually find my TechConnect information for Rockwell and bounced some ideas off their drive department. I actually had my set up right, just my set-point was very touchy. I didn't realize the intervals I was going to have to adjust my PID set-point in in order to get some results. I actually was informed by them to start the tuning by adjusting my acceleration and deceleration times. I was not getting a good reaction time until I turned the accel and decel down to about 1 second. @Dravik I thank you for all your help and I am going to try and adjust the P, I, and D a little bit to see if I can get smoother transitions.
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Old November 10th, 2017, 01:05 PM   #14
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Ahh nice, good luck!
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Old November 10th, 2017, 01:13 PM   #15
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Ahh nice, good luck!
Yhanks! Messing with the P,I, and D causes more grief. Only issue im having is that i cant get the drive to stabilize and run say 40Hz when im at 65-70psi on my sensor and stay there. It thinks it has to ramp up and then overshoot and then go back down. Im thinking my accel decel still needs played with a little
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