Appendix: Safe Torque Off (Sto); What This Chapter Contains; Basics - ABB MicroFlex e190 User Manual

Appendix: Safe Torque Off (STO) 187

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Appendix: Safe Torque Off
(STO)

What this chapter contains

The appendix describes the basics of the Safe torque off function (STO) for the
MicroFlex e190. In addition, application features and technical data for the safety
system calculation are presented.

Basics

The drive supports the Safe Torque Off (STO) function according to standards:
EN ISO 13849-1: 2015
EN ISO 13849-2: 2012
EN 61508-1/-2/-4/-6/-7: 2010
EN 61800-5-2: 2007, IEC 61800-5-2: 2016
EN 62061: 2005 + A1: 2013 + A2: 2015.
The STO function disables the control voltage of the power semiconductors of the
drive output stage, which prevents the inverter generating the voltage required to
rotate the motor (see diagram below). By using this function, short-time operations
(like cleaning) and/or maintenance work on non-electrical parts of the machinery can
be performed without switching off the power supply to the drive.