Safe torque off
The drive supports the Safe torque off function (STO) according to standards EN
61800-5-2:2007; EN ISO 13849-1:2008, IEC 61508, IEC 61511:2004 and EN
62061:2005. The function also corresponds to prevention of unexpected start-up of
EN 1037.
The Safe torque off function disables the control voltage of the power
semiconductors of the drive output stage, thus preventing the inverter from
generating the voltage required to rotate the motor (see the 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.
Start up and validate the Safe torque off function according to Safe torque off
function for ACS850 and ACQ810 drives application guide (3AFE68929814
[English]). The manual includes the safety data for the function.