Droop - Siemens SINAMICS S120 Function Manual

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Droop

Droop (enabled via p1492) ensures that the speed setpoint is reduced proportionally as the

load torque increases.

Speed controller with droop

The droop has a torque limiting effect on a drive that is mechanically coulped to a different

speed (e.g. guide roller on a goods train). In this way, a very effective load distribution can

also be realized in connection with the torque setpoint of a leading speed-controlled drive. In

contrast to torque control or load distribution with overriding and limitation, with the

appropriate setting, such a load distribution controls even a smooth mechanical connection

or the case of slipping.

This method is only suitable to a limited extent for drives that are accelerated and braked

with significant changes in speed.

The droop feedback is used, for example, in applications in which two or more motors are

connected mechanically or operate with a common shaft and fulfill the above requirements. It

limits the torque differences that can occur as a result of the mechanical connection between

the motors by modifying the speeds of the individual motors (drive is relieved when the

torque becomes too great).

Requirements

● All connected drives must be operated with vector control and speed control (with or

● Only one common ramp-function generator may be used for mechanically coupled drives.

Drive functions

Function Manual, (FH1), 10/2008, 6SL3097-2AB00-0BP5

without an encoder).

Vector control