Siemens SINAMICS S120 Function Manual page 423

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Properties of the parallel connection in STARTER

● The rating plate and equivalent circuit diagram parameters are those of the single drive.

● The parallel data set has no code numbers. All motor data is calculated from p0306 and the

code numbers of individual motors. The same interlock mechanisms apply as to single

● The "Motor data" screen still displays only the data for the individual motor selected.

Restrictions applicable to parallel connections

The basic governing principle of parallel connections is that the motors involved are

mechanically inter-coupled via the load. Where motors need to be decoupled from the

connection, the number of motors need to be reduced in p0306 by a DDS/MDS changeover.

Since the equivalent circuit diagram changes as a result, it may be necessary to commission

these data sets separately (e.g. motor data identification with reduced number of motors). The

power unit will otherwise apply false motor data.

An EDS changeover and, e.g. two SMCs must be used in cases where a motor with encoder

needs to be decoupled from connections operating with encoder.

Vector control with encoder for parallel-connected drives functions in the same way as for a

single drive if the drives are coupled via the load and the speeds do not differ by more than the

working-point-dependent pull-out slip.

Counter-example

The gear ratios used to couple the motors with the load are large and the backlash and elasticity

in the drive train are therefore high. If the load then causes one of the motors to rotate, but the

other is still stationary, the drive without an encoder will stall.

If a motor is defective, the individual motor will be shut down on overcurrent by the motor circuit

breaker. The power unit will be shut down by the control (if available) or, in the case of a turn-

to-turn fault in the motor, the power unit will go into the fault condition. The motor must then be

decoupled from the parallel grouping. Parameter p0306 is changed by the DDS/MDS

Overview of important parameters (see SINAMICS S120/S150 List Manual)

● p0300[0...n]

● p0306[0...n]

● p0307[0...n]

● p0640[0...n]

Drive functions

Function Manual, 06/2019, 6SL3097-5AB00-0BP2

Motor type selection

Number of motors connected in parallel:

Rated motor power

Current limit

Reference current

Basic functions

8.30 Parallel connection of motors