powerflex 755 Fallo de giro - Problema con el Giro en Powerflex 755

I have a Powerflex 755 controlling a Baldor induction motor of 100hp 3550rpm 120hz, the machine where this is a Langston Saturn II corrugated cardboard flexographic printer when the normal start is made (2 wires) the motor works correctly everything is fine but when use the Jog function the motor for approximately half a second turns in the opposite direction and then advances to its normal direction this causes the entire section of the machine to make a small jump damaging the gears progressively, it has reverse disabled, it is in control at 2 threads, sensorless vector control mode (tested in v/hz and does the same) no encoder used, 0-10V speed reference acc ramp 35s dec 10s, jog acc is at 10s and jog speed it is at 1hz since if you put it more the problem becomes more noticeable, someone who has experienced something similar to help me, thanks

Español

Tengo un Powerflex 755 controlando un motor de inducción Baldor de 100hp 3550rpm 120hz, la maquina donde esta es una Impresora flexográfica de Cartón corrugado marca Langston Saturn II cuando se hace el arranque normal (a 2 hilos) el motor funciona correctamente todo bien pero cuando se usa la función de Jog el motor por aproximadamente medio segundo gira al contrario y luego avanza a su dirección normal esto provoca que toda la sección de la máquina haga un pequeño salto dañando los engranajes progresivamente, este tiene deshabilitado la reversa, está a control a 2 hilos, modo de control a vector sin sensor (se probó en v/hz y hace lo mismo) no usa encoder, referencia de velocidad de 0-10V rampa de acc 35s decc 10s, acc de Jog está a 10s y la velocidad de Jog está a 1hz ya que si se le pone más el problema se hace más notorio, alguien que le haya pasado algo similar que me dé una ayuda, de ante mano muchas gracias

Check these items.

Contactor - Could be single phasing / cross phasing.

Motor insulation - could be breaking down and can't handle inrush current causing a single-phase operation.

Motor wiring from drive to motor - check wiring for insulation damage / resistance. etc.

JTCat said:

Check these items.

Contactor - Could be single phasing / cross phasing.

Motor insulation - could be breaking down and can't handle inrush current causing a single-phase operation.

Motor wiring from drive to motor - check wiring for insulation damage / resistance. etc.

Click to expand...

A few minutes ago I checked another printing press that has the same motor and the same frequency variator and it does the same, only that due to the mechanical relationship of the gears it is not as noticeable as in this machine, that is, I have 2 with the same problem (both have parameterization basic data, motor data, speed reference, ramps and start mode) I have the theory that with an encoder I could solve this!... but it is the first time that it happens to me and I don't have the equipment to make a coupling and place the encoder, I have a 20-750-enc-1 available and a 4096pp Heidenhain incremental encoder

How is the jog function enabled/wired? Are you using pushbuttons or the local keypad? An encoder would certainly improve position sensing, but I think you should still have no reverse motion without it, if reverse is disabled. Is it possible that the magnetizing current is causing the rotor to re-align to the a pole in the motor, then moving forward?

A few thought on this
What is on the motor name plate without that information we are just guessing on how to set it up.
From what you posted you want to run at 3550 rpm’s at 120hz that information tells me that you are expecting that this is a 4 pole motor. The base speed of a 4 pole motor at 60hz is 1800 with the normal slip I would expect the motor run about 1750 rpm this matches up with the information you provided
You are running this without an encoder feedback that means that you are operation in V/F or open loop vector from the sound of it you are in open loop vector
If open loop vector most fvd’s use counter emf as motor speed feedback and that works good
You say you want to jog it at 1 hz well that’s way too low for that setup you should never run a open loop system below 6 hz below that point they become unstable. In your case it looks like the vfd thinks the motor is running too fast and tries to correct it by reversing the output rotation.
Try setting the jog speed to something above 6 hz. The best solution would be to install an encoder on the motor and set up the vfd as a Flux Vector I would bet you problem will go away.
I am surprised that it vfd was not setup as flux vector from the factory on a printing press accurate speed control is critical for good quality printing.
I have rum Flux Vector drives at .5 hz on milling machines many times without any problems
Make sure that the drive parameters are setup correctly to match motor name plate information
And just a thought I have worked on many printing presses and a motor speed of 3600 rpm seams high to me that would require a large gear reduction to get it in the operating range.
Let us know how you make out

GaryS said:

A few thought on this
What is on the motor name plate without that information we are just guessing on how to set it up.
From what you posted you want to run at 3550 rpm’s at 120hz that information tells me that you are expecting that this is a 4 pole motor. The base speed of a 4 pole motor at 60hz is 1800 with the normal slip I would expect the motor run about 1750 rpm this matches up with the information you provided
You are running this without an encoder feedback that means that you are operation in V/F or open loop vector from the sound of it you are in open loop vector
If open loop vector most fvd’s use counter emf as motor speed feedback and that works good
You say you want to jog it at 1 hz well that’s way too low for that setup you should never run a open loop system below 6 hz below that point they become unstable. In your case it looks like the vfd thinks the motor is running too fast and tries to correct it by reversing the output rotation.
Try setting the jog speed to something above 6 hz. The best solution would be to install an encoder on the motor and set up the vfd as a Flux Vector I would bet you problem will go away.
I am surprised that it vfd was not setup as flux vector from the factory on a printing press accurate speed control is critical for good quality printing.
I have rum Flux Vector drives at .5 hz on milling machines many times without any problems
Make sure that the drive parameters are setup correctly to match motor name plate information
And just a thought I have worked on many printing presses and a motor speed of 3600 rpm seams high to me that would require a large gear reduction to get it in the operating range.
Let us know how you make out

Click to expand...

hello, how are you, thank you very much for taking the time to respond, well, I'll tell you the motor information plate is dual

100HP 1780RPM 124Amps 460V 60Hz
100HP 3555RPM 120Amps 460V 120Hz
both Duty Cont

the person who programmed it the first time used the data at 120hz, I left them using the data at 60hz since all the other machines work at 1780 RPM but it still failed me, the Jog is at 1hz because if I put more then the jump does it much more and there is a risk of damaging the gears by default it comes at 10hz, and there are already 2 machines that I have like this with the same motor and frequency variator, left a short so you can see how the machine does

https://youtube.com/shorts/1Cyauz_arrQ?feature=share

Robb B said:

How is the jog function enabled/wired? Are you using pushbuttons or the local keypad? An encoder would certainly improve position sensing, but I think you should still have no reverse motion without it, if reverse is disabled. Is it possible that the magnetizing current is causing the rotor to re-align to the a pole in the motor, then moving forward?

Click to expand...

hello, how are you, thanks for replying, the start and jog are activated by pushbuttons but they go to the PLC and this activates relays where the signal from the drive goes to 2-wire control, at least that's what I think that by having an encoder the drive would know everything moment the position of the motor since when I looked at the HIM screen at no time did I see Negative references to activate reverse

From that information the motor is clearly a 4 pole motor
The drive should have been programmed for the 60Hz values
There should be a parameter for pole numbers it needs to be set for 4 if it is not the motor will run unstable. The drive calculates everything from the base frequency and the number of motor poles.
In the feedback it look at the counter emf expecting it to be for 4 pole motor at 60hz
The way the motor performs changes when it operates above base speed I this case 60hz / 1800 rpm the number of poles parameter is more important than the rpm the output rpm’s is determined by the output frequency and number of poles in the case of a 4 pole motor at 60hz the base speed is 1800 rpm at 50hz the same motor will run at 1500 rpm.
No motor will be stable on a standard vfd below 6 hz without encoder feedback in a flux vector drive I would not expect it to be stable.
As for the 1 hz jog speed you say the motor jumps that tells me that your acc rate it to fast I would start that out at 15sec and work it down from their. Also keep in mind the acc and decl rates are calculated from the base speed frequency in the drive. with the setting of 120hz with an acc rate or 10 sec it will only take 5 sec to reach the 60hz the base speed. Also some vfd’s have a start boost setting that will actually boot the output voltage at the start to allow heavy loads to start if don’t need that it could cause the motor to jump. There is also a starting output voltage that may be set to high for your application. You say they originally the jog speed was set at 10hz that would be a good speed for jog
If you need to go below that then you should really consider going with a Flux Vector Drive using encoder feedback
The control method from the plc is not relevant here it only receives a run command or jog command from the plc the speed reference may be from the plc or analog from the drive input
Check your settings and let us know how you make out