Powerflex 755 error autotune

[janasamara]

Hi ,

I am a trying to configure powerflex 755 to work a close loop , but I´m have trouble with autotune rotine. When I choose the rotate tune , the test starts normally and performs the static test successfully. Then when it is going to realize the moviment of the axis occurs the following error : Number 79 ( Excessive Load).
If I try to work without performing this test another error appears : error number 7 (motor overload) and the engine does not respond to speed programs very well.
I tried to find in the rockwell manual some information on why this error occurred in autotune but I did not succeed and I believe that for the drive to work properly in closed loop I have to perform the autotune correctly.
I do not know what to do. Is it a misconfigurate parameter ?
Please can anyone help me ?
Thank you

 

[ptonsparky]

There are others that will be more informed, but I thought that Autotune should be done with a motor that has no load connected to it.

 

[janasamara]

Thank you for replying. The motor dos not have a coupled load.

Thank you for replying

 

[Jraef]

First, did you make absolutely sure the motor nameplate data entered into the VFD parameters is correct? Autotune has to start off with correct motor nameplate data, it does not do that for you. Even if you entered it, make sure there isn't a mistake. One error I have seen more than once is a misplaced decimal point, for example .10A instead of 10A.

If that is correct and there is no load, then another possibility is that you have a capacitive charging current problem in your cables. The VFD can't actually tell the difference at this point, all it sees is that the current exiting the drive is exceeding the current it thinks it should be (based on that nameplate data, hence if that is incorrect, it is assuming based on invalid data).

 

[petersonra]

sometimes autotune works really well, other times it just doesn't. I have never been able to figure out why it does or does not work. it is one of those AB mysteries to me.

I will say that usually someone in the tech support department knows why and can help you work through it. Often with me it has been some obscure setting that needs to be changed and than the autotune works fine. And there is always someone that knows this. Yet AB does not chose to change the software so these settings are made by default. It is like the RSLinx quirks AB has known about for 15 or 20 years and they still refuse to change the defaults so the stuff works.