Safe Torque Off (Option +Q967) - ABB ACS800-04 Hardware Manual

Safe torque off (option +Q967)

The drive supports the Safe torque off (STO) function according to these standards:
•
EN 61800-5-2:2007
•
EN ISO 13849-1:2008/AC:2009
•
EN ISO 13849-2:2012
•
IEC 61508 ed. 1
•
EN 62061:2005/AC:2010
•
EN /IEC 60204-1:2006/AC:2010
The function also corresponds to an uncontrolled stop in accordance with category
0 of EN/IEC 60204-1 and Prevention of unexpected start-up of EN 1037.
The STO may be used where power removal is required to prevent an unexpected
start. The 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 (such as cleaning) or maintenance work on non-electrical parts of
the machinery can be performed without switching off the power supply to the
drive.
An example circuit diagram is shown below.
WARNING! The Safe torque off function does not disconnect the voltage of
the main and auxiliary circuits from the drive. Therefore, maintenance work
on electrical parts of the drive or the motor can only be carried out after
isolating the drive system from the main supply.
Planning the electrical installation 51
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