Safe Torque Off Function; What This Chapter Contains; Description - ABB ACS560 Hardware Manual

Safe torque off function

What this chapter contains

This chapter describes the Safe torque off (STO) function of the drive and gives instructions
for its use.

Description

The Safe torque off function can be used, for example, to construct safety or supervision
circuits that stop the drive in case of danger. Another possible application is a prevention
of unexpected start-up switch that enables short-time maintenance operations like cleaning
or work on non-electrical parts of the machinery without switching off the power supply to
the drive.
Note:
The Safe torque off function does not disconnect the voltage from the drive, see the warning
on Use (page 154).
When activated, the Safe torque off function disables the control voltage of the power
semiconductors of the drive output stage (A, see diagram on
(R0...R2) (page 149)), thus preventing the drive from generating the torque required to rotate
the motor. If the motor is running when Safe torque off is activated, it coasts to a stop.
The Safe torque off function has a redundant architecture, that is, both channels must be
used in the safety function implementation. The safety data given in this manual is calculated
for redundant use, and does not apply if both channels are not used.
The Safe torque off function of the drive complies with these standards:
Standard
EN 60204-1:2006 + A1:
2009 + AC:2010
Name
Safety of machinery – Electrical equipment of machines – Part 1: General require-
ments
Safe torque off function 147
12
Connection principle