PowerFlex 755 parameter assistance

[forqnc]

Hi All,
This is my first PowerFlex 755 drive setup and I am having an issue with when I start the drive it runs at my minimum speed 5Hz, but parameter 2 shows the command speed reference coming from my potentiometer.
This is a new build, the motor spins freely.
The setup is just a Stop/Start with the speed adjustable from the potentiometer.
Can anyone assist on what I am obviously overlooking.
PDF shows the parameters I have changed.

Thank in advance for any assistance.

 

[DarrylR]

Check HIM to see if in Auto. Could be in manual mode.

 

[forqnc]

Yes, HIM shows Auto.

 

[DarrylR]

Only thing that comes to mind, other than checking the control wiring, is to ask if you're using the safety inputs. If not, the jumper needs to remain installed for the drive to operate.

 

[rkukl]

can you use analog input on main control board instead of the add-on I/O module? seems you are not getting reference and drive is running at set minimum speed.

 

[rkukl]

did you check jumpers?
from Manual Publication 750-IN111B-EN-P - March 2022
PG 4

 

[robertmee]

What do you have parameter 300 set to?

 

[forqnc]

Only thing that comes to mind, other than checking the control wiring, is to ask if you're using the safety inputs. If not, the jumper needs to remain installed for the drive to operate.

We are using the Safe Off Torque board requested by the customer and have it wired +24VDC to SP+ and SE+ and 0VDC to SP- and SE-.
And yes we removed the jumper.

can you use analog input on main control board instead of the add-on I/O module? seems you are not getting reference and drive is running at set minimum speed.

The 755 does not have an analog input on the main board see below, and I agree it is as if the drive is not seeing the reference speed and running at minimum. It also runs at minimum when I try to Jog, does not run at my 20Hz in Jog Speed 1 parameter Port 0 556

View attachment 68528
did you check jumpers?
from Manual Publication 750-IN111B-EN-P - March 2022
PG 4

Yes Jumpers are on Current mode as per below on the 22-Series I/O module.

What do you have parameter 300 set to?

Parameter 300 is set to Hz


Thank you for the replies and advice guys.

 

[clintm]

I've never used the STO board with a PF755. Assuming it's not the issue....

What is your motor control mode set to (P0/35)? It looks like autotune might have been run when configured for a permanent magnet motor. If it is not a PM motor and you have changed the control mode, have you re-run autotune?

Is this a speed regulated application? If so, is it possible during troubleshooting some other settings were modified, like torque control, position control, or other, that don't pertain to your application? You can monitor P0/313 to see the active control mode. P0/309-312 specify the control per mode.

You might have to follow the control block diagrams to see where you are limited. They are in Appendix B of (750-pm001-en-p). I believe if you're online in CCW you can view those with live data. There are many potential paths between P0/2 and P0/1.

 

[forqnc]

Embarrassingly I return with an update for any future viewers that may have a similar situation.
I was finally able to have a teams meeting with my Distributor.
By sharing my screen he was able to verify the parameters I had set were correct.
He checked parameter 420 Drive O/L which was at its default setting of 3.
He concluded, what I suspected, that the drive was limiting the Output Frequency due to a possible mechanical/other issue.
The motor spun freely by hand, but I proceeded to unloosen the belt tensioner to remove the belts and try.
As I was doing this I was looking at the motor wiring, which I had not wired up, and decided to check the motor was wired correctly.
As I touched the first phase wire from the drive it popped out of the wire nut,
I re-terminated it and checked all other connections.
Tried the drive and everything ran as it should. So the motor had lost a phase and the drive was doing its job to limit the output.

Lesson learned, don't always doubt yourself with new equipment, still check the basics if you have problems.
Thank you for all the replies and assistance.

 

[joseph_e2]

Embarrassingly I return with an update for any future viewers that may have a similar situation.
I was finally able to have a teams meeting with my Distributor.
By sharing my screen he was able to verify the parameters I had set were correct.
He checked parameter 420 Drive O/L which was at its default setting of 3.
He concluded, what I suspected, that the drive was limiting the Output Frequency due to a possible mechanical/other issue.
The motor spun freely by hand, but I proceeded to unloosen the belt tensioner to remove the belts and try.
As I was doing this I was looking at the motor wiring, which I had not wired up, and decided to check the motor was wired correctly.
As I touched the first phase wire from the drive it popped out of the wire nut,
I re-terminated it and checked all other connections.
Tried the drive and everything ran as it should. So the motor had lost a phase and the drive was doing its job to limit the output.

Lesson learned, don't always doubt yourself with new equipment, still check the basics if you have problems.
Thank you for all the replies and assistance.

I have an aluminum coupling on my desk as a reminder to ALWAYS double check what other people tell me they checked. It connected a DC tach generator to a gearbox for speed feedback. The system was horribly unstable "suddenly" and the symptoms pointed to the tach generator, so I asked the electricians to dismount and check it, which they said they did. So I dug into a bunch of other things, getting more and more confused and frustrated over the course of a day with multiple calls to AB support for the PowerFlex DC drive. Until I double-checked the tach generator. I pulled it off and the coupling was loose. So loose that it had ridden up on the shaft and was rubbing on the housing enough to actually melt itself.



"Trust but verify"

Always.