Hi,

We have one machine with two motors driving same gear train through two different gear box. Master drive (40 HP, AB PF 700) is configured for speed control and slave drive (30HP, AB PF 700) is configured for torque control receiving 0-10VDC as Torque reference from master drive (torque command configured as 0-10VDC output). At the beginning machine starts normal but after few minutes of operation over load clutch of master drive slips (Ton-Torque). Is there any thing wrong in this configuration or there is any design issue. While in operation master drive draws 30 amps while slave drive draws 18amps.
Thank you,

Shree

 

In theory, there is nothing wrong with what you believe your configuration is. You are employing load sharing.

I would verify that, in fact, the slave drive is in torque control and not speed control.

If you believe that the master is simply doing too much of the work and the slave is not doing its share you could increase the scale factor for the torque command to the slave drive, either on the master output side, or the slave input side.

If it is, then I would call Rockwell to have them sort this out for you.

Realizing that AC motors develop torque by applying frequency to create slip.... and doing so requires an accurate motor model within the drive (firmware and motor data), particularly when doing so with an open loop vector configuration..... well... this entire statement is a hint. The drive can be "tweaked" if you know how the motor model works..... not that it should have to be.

If unsuccessful, call your local ABB representative and ask them about the ACS800 DTC drive... open loop, using the fiber optic interface for loadsharing with windowing to detect slip of the master or slave drive train (4 to 4 parameters in each drive). Approx 1% torque regulation open loop with excellent dynamic response near zero speed... open loop.

No, I do not work for ABB.

 

I feel - the torque reference given through the 0-10 V analog signal is not the right solution. The best option can be drive to drive communication. ABB ACS800 is having that thru FO cable.

 

Thanks for the reply.

Drive is Allen Bradley (AB) not ABB and do not have any communication set.

Now the machine is operation but I would like to know how to set up in case I need to change motor or Drive with new one.

Thanks and regards,
Shree

 

If the load is hanging you will need to rent chain motors to temporarily take the load while changing motors.

A good thing to do now would be to the the parameter settings out of the current drive and save them to a laptop. If a drive goes out it may be so dead that you won't be able to get them then. This way you won't need to re-tune too much by loading the old parameters in and will be close enough to move to check detailed tuning.