Hello Experts

We are using SINAMICS G120 to control 2 Nos. Induction Motors in Parallel.
Drive Speed / Torque reference is through PROFINET from S7-300 PLC.

My question is :

How should we set the reference values for Current ( P2002 )  and Torque ( P2003 )
(  Based on speed / torque of Each Motor or should it be set = Sum of the two Motors.

Thanks

Navnag

For the drive, it is based on the sum of the two motors.  You need external protection and shutdown for each motor, based on individual motor current.

You cannot control individual torques and you cannot run with vector control.  Not sure of your application, but you may be better using two inverters with peer-to-peer communication for load share.

Hello

I can confirm Jeff post.

Also see here (link to mm4 faq).

2 inverter with peer-to-peer communication is best solution.

For no high dyinamic performance sometimes I made torque control also with probibus communication beetwen inverters. 

Regards

Hello all

Many thanks for your replies.

I will set the Reference Current and Torque to sum of the 2 motors.

@jeff - Yes, we have provided individual motor overload protection at the output of the drive.

@Miami @mindware -  I haf followed the FAQ : https://support.industry.siemens.com/cs/in/en/view/

As per the FAQ Sensorless vector control is possible if the motors are mechanically coupled. :

 "encoderless (sensorless) vector control (SLVC) are permissible. However, when using encoderless (sensorless) vector control, the motors must be mechanically coupled. "

and NO the application does not require a high dynamic response.

please correct me if I am missing something.

Cheers

Navnag

Good to know that you can do SLVC with coupled motors, that's news to me but I guess it makes sense in retrospect.  So, when setting up the drive, enter 2x current, 2x power and 2 x torque.  If I remember, torque limitation is a %, so that does not change.  Just pretend you have one big motor and you are ready to go.  The motor identification should hopefully sort things out.

There is a risk of damaging the drive if one of your output contactors opens under load.  Be very sure that you have early break contacts on your output contactors and the you open the Pulse Enable in case of a motor fault.

Yes. I have Set the Reference Torque now to the Sum of the Rated Torque of the two motors and system seems to be operating fine.

We have provided thermal overload relays for individual motors and their trip contacts are interlocked with Pulse Enable. Both the OLRs should be healthy for pulse enable.

@Jeff - When entering the Motor Data, you do not have to enter 2xCurrent , 2x Power , 2x Torque . Starter allows you to enter the data for One motor and then you can define the no of motors in parallel.

I was only confused about the Reference Torque / Current ( When controlling through PROFIBUS/PROFINET )

Thanks Friends.

Cheers

 Navnag