ACS800, Speed Limits

JGax

Member
Join Date
Nov 2013
Location
Mexicali
Posts
28
Hi all.
First thanks in advance.

I'm working with a conveyor application. It has a ACS800 that ran a motor to drive a reducer and finally a chain conveyor.

In general its running fine... we use fieldbus RETA01.

We want to ran at 3000 rpm. drive receive the info from plc and starts... but the speed just reach 2780 rpm.... no more..... I check the Speed limits on 20.02 parameters.... which is set to 3200 rpms....

Now, seems like limits are a calculation from motor data plate on 99.xx parameters.... and change does not effect the speed....

DTC mode is selected.... supervision parameters are now for testing purposes....

Is the any way to make the motor at higher speed that what VFD calculate?

Thanks for your help
 
Have you checked actual frequency from the drive?

Sounds like the motor is running at its asychronous speed.

Did you do an ID run from the ACS800?

What are your settings on 20.08, 99.02 and 99.04?

Why run it in torque mode when you want a constant speed? Might be torque limiting the speed.
 
Last edited:
When you have a VFD in torque control mode, you are telling it that torque is the primary thing you want maintained, speed is secondary. So the drive may or may not respond to a speed command the same way.
 
Well, I talked to ABB support....
After review all what some of you asked above... all is ok and performs ok.

Reduced the problem to the communication profile... its using the Generic Profile and it limit the reference speed sent over Ethernet.... to exactly 2872.7
lol

I have to change to ABB profile so that reference speed is not limited.... puff....

Is not fun... have to change PLC logic.

Thanks for your support.... as soon I finish the logic and test will update results.

Regards
Jesus
 
Just as an aside, DTC, or Direct Torque Control, does NOT infer that the drive command mode is torque control. DTC is the motor flux control method ABB has chosen to use for their high performance drives, as opposed to using the more popular field-oriented control through a PWM driver that most other drive manufacturers use. It is very likely the OP was in speed control mode through this whole exercise.

Keith
 
Hi all

UPDATE!!

Well.... I call a local company to help with this... but curiously they don't believe what ABB support says about change the profile to get the reference speed....

Im not sure what really happened but those guys change the nominal motor data into parameters 99.xx.

Nominal hz of 60 they changed for 80hz
Nominal rpms from 1720 nominal they typed on 2220

Mag Id again and all seems to work now.... the reference speed was increased.....

What do you guys think of?

if Profile where the issue as the reference speed was truncated by... the no mater what the data plate is.... the reference should no go any higher its a bits issue....

guy from ABB says that Generic profile truncate the reference from PLC... now I don't believe that...

Regards
 
You need to find the manual that describes the profile data. The speed may not be in rpm value, but in a percentage value with some weird scaling. It's been awhile, but I sorta kinda remember that being the case.
 
Thanks I will look at....
I was not there when the guys make some changes and they refuse to explain what solved the issue....
I'm thinking they don't know exactly what happened... lol

I need the truth
 
I have never tried to use the generic profile before. i have always used the ABB drive profile or the ODVA drive profile.

I know with the ABB drive profile i have used the speed command value will go to +/-20000 bits through the adapter and that equates to the value in 46.01 or 46.02 depending on whether you are using speed or frequency command mode.

If the generic profile works the way I think it does you are mapping values directly into specific drive parameters. What parameter are you mapping speed into?

When you use the word "nominal" I assume you mean motor nameplate data values. changing those seems like a pretty odd thing to do. Please confirm what you mean when you say "nominal".

Keith
 
That is correct, Gene Bond. that is why I was trying to confirm if by "nominal" he meant "nameplate". If the frequency and speed were changed without a corresponding change in nameplate voltage the motor will be undermagnetized. I'm not sure if the autotune function would account for this or not. My guess is it would to some degree but not completely.

Keith
 
I have seen ABB (Baldor/Reliance) RPM-AC motors with some pretty wacky nameplates! The above setting sounds like something they'd do. Normally when I run into a nameplate that I really don't believe, I do a little manual tuning at 30hz or so (fixed v/f mode), playing with the voltage to see where the valley in No-Load Amps is, and figure that the nameplate voltage should be about 20% above this (of course calculating it for nameplate Hz) (or just after the no-load amps start to rise), for a basic sanity check.

I *ASSUME* the DTC mode is like most manufacturer's flux-vector modes, where the nameplate data is just a starting point for auto-tune, and actual voltage levels are the result of current based on load, resistance, primary and secondary inductance (power factor), etc. I have heard good things about DTC, other than issues with low inductance and/or higher modulation frequencies on high performance applications.

So, it may not matter that much.
 
That is correct, Gene Bond. that is why I was trying to confirm if by "nominal" he meant "nameplate". If the frequency and speed were changed without a corresponding change in nameplate voltage the motor will be undermagnetized. I'm not sure if the autotune function would account for this or not. My guess is it would to some degree but not completely.

Keith

I have never tried to use the generic profile before. i have always used the ABB drive profile or the ODVA drive profile.

I know with the ABB drive profile i have used the speed command value will go to +/-20000 bits through the adapter and that equates to the value in 46.01 or 46.02 depending on whether you are using speed or frequency command mode.

If the generic profile works the way I think it does you are mapping values directly into specific drive parameters. What parameter are you mapping speed into?

When you use the word "nominal" I assume you mean motor nameplate data values. changing those seems like a pretty odd thing to do. Please confirm what you mean when you say "nominal".

Keith

Nominal is the motor data plate.
And I verify again about the Profile.... the Generic is able to handle +-20000 as reference, so that was not the problem in this case...
Still looking for the real issue....
 
That is correct, Gene Bond. that is why I was trying to confirm if by "nominal" he meant "nameplate". If the frequency and speed were changed without a corresponding change in nameplate voltage the motor will be undermagnetized. I'm not sure if the autotune function would account for this or not. My guess is it would to some degree but not completely.

Keith

Well the guy came again to check another system with same symptom...
again he type in motor data... Nominal RPM from 1720 he typed 2220, for Nominal Frec of 60 he typed 80... and the ran ID Mag.... then just change the limits on 20XX and 11XX or 16XX he did not allow me to saw again..... lol
but I have a old parameter backup, will upload and compare and share what he exactly changed...

Regards
 

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