Page 64
6 Functional safety technology
This section provides information on the ARS 2000 SE servo drives with the integrated safety function
STO („Safe Torque Off“).
6.1 General
With an increasing degree of automation, the protection of persons against dangerous movements
becomes increasingly important. The so-called functional safety describes the necessary measures in
the form of electrical or electronic devices in order to reduce or eliminate the hazards that are caused
by malfunctions. Under normal operating conditions, protective devices prevent human access to
dangerous areas. In certain operating modes, however, for example during the set-up, persons are
required to be present in these dangerous areas. In these situations, the machine operator must be
protected by drive- and control-internal measures.
The integrated safety technology provides the control- and drive-specific conditions for the optimal
realisation of protective functions. Planning and installation become less labour-intensive. Compared
to conventional safety technology, the machine functionality and availability can be increased by the
use of integrated safety technology.
The servo drive ARS 2000 SE series devices with STO are delivered with integrated functions for
safety-related motion monitoring and motion control.
6.2 Description of the integrated safety function STO
Use the function “Safe Torque Off” (STO) whenever you have to reliably disconnect the energy supply
to the motor in your particular application.
The function “Safe Torque Off” switches off the driver supply for the power semiconductor. This makes
sure that the power stage does not feed any significant current into the motor and thus that the motor
does not start moving unexpectedly, see
For further information please refer to the Product Manual “STO (Safe Torque Off) for the servo drives
ARS 2000 SE”.
Product Manual „Servo drives ARS 2100 SE“
Version 5.0
