Question about ABB ACS550

Hello all,

I am new to the forums and somewhat green in the aspect of setting up these drives myself, so I Apologize in advance if I seen a little new to the situation, and I appreciate all the help and advice I can get.

I am installing and commissioning one of these units as a test in my plant and here is what I have as follows.

I simply need to be able to control torque output, and speed output seperately on this drive by the use of trim pots ( pref 10k ). I have been reading the manual and researching as best as I could through all my references, and I finally decided to post about it. I know it may sound simple enough... but I am getting a little frustrated.

The reason I need to use the pots is that operators have to use this drive to control motors on gearboxes driving LARGE (1-2t) reels of pipe, and I have to keep this installation as user friendly as possible as they will destroy it with a hammer if it doesn't work the way they want it to.

Again,

thanks for you help, and I look forward to learning as much as possible from your experiences.

John

John, I can help you with this drive. I am not clear on how you want to control it, however. You mention torque and speed but you really can't control both at the same time.

Drives usually come from the factory set up for speed control. There is a torque limiter available but you don't normally actively control it. The torque the motor produces is determined by the load at the speed you are commanding.

On the other hand, you can change the drive configuration so that torque is the control element. In that case, there is a speed limiter but it is not normally actively varied. The motor seeks to produce the commanded torque and will increase speed up to the point where the load requires that much torque or bump against maximum speed limit.

Tell us about the load machine and what you want to accomplish and we may be able to help with these choices.

Thanks for the quick reply.


THe drive is turning a reel of pipe. The reel obviously gets larger as the diameter of the material on the reel moves outward, and sometimes the pipe can weigh 50lbs/4' segment so it can get very heavy very fast. I need my operators to be able to adjust the speed as it has to slow down as the reel gets larger, but also increas the torque as the speed decreases to compensate for lack or momentum as well as tension on the pipe comung out of the extruder, etc etc.

I hope this is more information. I have been trying to get this done for a while, and I need t finish as we are not having must luck with the old speed control drives that are in there right now.

I realize after writing this that it looks like and inverse function would be useful to me, however, because of the complete range of pipe we run (1/2" up to 6" or bigger on reels) that a simple function macro is not really what we need here.

thanks again for all your information.

John

Your application sounds like a winder. The requirement sounds like:
1. You need a certain defined tension in your pipe as it comes off the extruder
2. The diameter of the reel increases as the material accumulates on the reel
3. The extrusion speed is constant and hence, the reel speed would reduce as the dimeter builds up.

Normally an application of this kind would require that the diameter is continuously calculated to recalculate the torque setpoint. This application does not call for constant torque. It calls for torque control with the torque increasing proportionally with the diameter.

Normally, we have a PLC (maybe integrated into the drive controller)that calculates the diameter and sets a speed setpoint that is slightly higher than the expected reel speed. The torque setpoint is set based on the calculated diameter and the tension setpoint. The drive can be run in speed mode with the torque setpoint being set as the +ve torque limit of the speed controller. But with the ACS550, you do not have the flexibility to do this kind of programming into the drive. If you have no access to a PLC within this project, the operator will have to fool around with the potentiometers. The tension pot should be connected as the +ve torque limit of the drive. This will have to be increased by the operator as the dimeter builds up. The speed reference should be another pot that the operator sets to a value high enough for the pipe to be pulled tight. He can then just leave it there because the actual speed is only going to reduce. The risk is that if the pipe were to snap, the reel is going to shoot off to the speed that was set on that pot.

You will find a lot of previous posts on this subject if you search for 'Winder' on this forum.

thank you very much. I agree with you and your assessment. The problem I have is that you are right the operators will have to play with the pots on their own to become comfotable with the the unit and how they have to adjust it with the changing pipe diameter and so on.

basically I would attach a 10k pot to the AI1 input and the "torque" pot to the AI2 input? and then where would I get my torque and speed references from as this motor and gear box do not have tachs attached to them or CTs of any kind.

thanks again

the next idea I was wondering about would be, they list a "torque switch" on the diagram for use in the torque macro. would I then only use 1 10k pot and the switch would then constantly be changing the use of the pot from speed to torque and vice versa?

thanks
john

L0sts0ul said:

and then where would I get my torque and speed references from as this motor and gear box do not have tachs attached to them or CTs of any kind.

Click to expand...

All AC VFDs include CTs. Conversion from current to torque is complex and I guess all VFDs (ACS550 does) normally handle that function. Regarding speed, the VFD can always estimate the motor speed based on the frequency that is being delivered and the torque. So a tacho is not an absolute must unless you plan to have a high degree of speed and torque control accuracy.

Frankly, I have no clue about your pipe extrusion application. So, I don't want to be giving you detailed guidelines on how to make this work. We have done innemerable winders for strip applications and that is where I could have helped.

fair enough.

I will have to research more. I am not engineering this, I am just installing it as per my boss, who doesn't have any clue as to what he is doing at this point.. LOL

HE handed it to me and told me to install it.

thanks for your help.

You cannot control torque and speed at the same time. What you are describing has been rightly called a constant tension winder application.

Typically, the drive manufacturer supplies special winder software for these jobs. The basic concept is for the winder to be a speed regulator with either a measured or calculated tension feedback signal which goes to a PID controller in the drive.

The operator sets the desired tension and the drive regulates speed to keep the tension constant. Torque is not controlled but results from the other control signals and the error between the desired and actual tension.

Look up winder control on the web and you will see what we are talking about.

In the ABB world, winder control is usually done with the ACS800, not the 550. The only way I see doing any kind of winder control with your 550 would be to install a tension measuring device somewhere and using that with the PID macro to get tension control.

As for the switch you mention in the Torque Macro, it simply switches the drive from a speed regulation configuration to a torque regulator configuration. Both do not occur at the same time.

DickDV said:

You cannot control torque and speed at the same time. What you are describing has been rightly called a constant tension winder application.

Typically, the drive manufacturer supplies special winder software for these jobs. The basic concept is for the winder to be a speed regulator with either a measured or calculated tension feedback signal which goes to a PID controller in the drive.

The operator sets the desired tension and the drive regulates speed to keep the tension constant. Torque is not controlled but results from the other control signals and the error between the desired and actual tension.

Look up winder control on the web and you will see what we are talking about.

In the ABB world, winder control is usually done with the ACS800, not the 550. The only way I see doing any kind of winder control with your 550 would be to install a tension measuring device somewhere and using that with the PID macro to get tension control.

As for the switch you mention in the Torque Macro, it simply switches the drive from a speed regulation configuration to a torque regulator configuration. Both do not occur at the same time.

Click to expand...

Thanks, you have answered a couple questions I have. I believe my boss was sold or he asked for this drive in error as he is under the assumption that he can control both at the same time.

I understand the corelation between the torque and speed, and how a plc would adjust accordingly using a feedback device. The 550 as you can can't do this so I Will have to setup this drive using it as a simple vfd, with a speed pot, and he will have to either decide to send it back, or let me put in the plc I have been asking for.

I have to retrofit 7 of these units for this setup as all the old drives are slowing crapping out. I am not sure that a plc setup is what he wants to do as per the higher initial setup costs.

thanks again.

winder control with the acs550

hi,

ok, so now that I have a little better understanding of what im trying to do here I still need to figure out how I can get the drive I have to do what I want it to do..or even if that is possible.

with the ACS550, I need to keep a constant speed, with the ability to adjust torque manually through a 10k pot. is this possible?

I guess the questions underlying in my head are something like,
I can't give the operators access to the drive controller itself to control the drive, they have to be able to access it from standard pushbutton operators, 2 or 3 position switchs, and pots. If I Was to allow them access to actually work with the control pad, they would destroy it, and probably play with it enough to screw up my parameters.

do you think I can do this with the acs550? I think I can, but I just need to understand the macros and how the control wiring works with the drive better. I believe the torque macro would work the best, as I can't use a closed loop to control the drive, the motors are somewhat archaic, and this is retrofit experiment. I unfortunately have no input on the drive that was chosen, or other methods of controlling this system.

I hope you can help me thanks.

John

L0sts0ul said:

with the ACS550, I need to keep a constant speed, with the ability to adjust torque manually through a 10k pot. is this possible?


John

Click to expand...

No this is not possible because you will still be trying to control torque and speed at the same time, something has to give.

Would it be possible for you to post some sort of sketch of the machine? I along with the others here are having a difficult time picturing what you want to do.

yup, lemme work on one, and I will get back to you...


you mentioned you worked in pipe before. its a basic pipe extrusion system, pipe is extruded from the die/extruder, runs through vacuum tanks, and cooling tanks, through the hauloff and saw, out to a winder that spools over hand. Some of the problems we have are the larger pipe has a tendency to overload the drive that is in there now and the electric brakes on the motors either aren't strong enough/or don't work to stop the back spooling of the pipe off the winder. Some of the spools get very heavy, so much as 1-2 tonnes sometimes as the pipe is sometimes 6+" in diameter and sometimes walls 1+" thick. reels are usually 10' in diameter.

I will try to post a diagram as soon as I can get cad, or even visio running again.

thanks

John, we might be getting tangled up a bit on terminology. When you say you need a constant speed, I suspect you mean a constant speed on the pipe product. Now, think about this a minute! If the product speed is constant, and the reel size you are winding the product is increasing in diameter as the product winds up on it, the the shaft speed of the winding spool has to slow down, doesn't it?

So, if the motor is driving the winding spool from the center shaft, the motor also has to decrease in speed as the reel fills with pipe product to keep the feed rate of the product coming out of the extruder constant.

That's what makes a winder like this so tricky. If that isn't bad enough, if you want to keep a constant tension or draw on the product as it leaves the extruder, the torque on the center shaft of the winding reel has to be low when winding directly on the core and increases as the product builds up to a larger diameter on the reel.

Unless you can install some way to directly measure the tension or draw on the pipe coming out of the extruder, the ACS550 is not the right drive for this job. I repeat, if what I have described above is your situation, then the ACS550 is not the right drive for the job.

If I have somehow described your situation incorrectly, please tell me where I've gone wrong and we can work things out from there.

DickDV

no, I was learning about winder applications, and you are exactly right.
I understand how the torque relates to the diameter of the material, and how it has to increase as the diameter increases. The constant speed part is strictly because the hauloff and the extruder are set to run at certain speeds (within a proportional amount)with each other ( set by hand not a closed loop) and it would be nice if I could integrate the "speed" of the winder into the system with the haul off and the extruder. However, I don't have this option due to the manufacturing company not willing to run this kind of automation, I WOULD LOVE TO SET THAT UP!!!.

so, in the mean time I am stuck with the ACS550 that my boss has purchased, and it sounds to me like I am going to have to set it up as simply a VFD with a speed pot, and an on/off switch because this drive is the wrong drive for this application.

am I correct here?
John