1 Introduction1.1 Purpose of the ManualThis manual provides information for use of Danfoss VLT®frequency converters in functional safety applications. Themanual includes information about functional safetystandards, Danfoss VLT® frequency converter Safe TorqueOff (STO) function, the related installation and commis-sioning, and service and maintenance for STO.VLT® is a registered trademark.1.2 Additional ResourcesThis manual is targeted at users already familiar with theVLT® frequency converters. It is intended as a supplementto the manuals and instructions available for download atdrives.danfoss.com/knowledge-center/technical-documen-tation/. Read the instructions shipped with the frequencyconverter and/or frequency converter option beforeinstalling the unit, and observe the instructions for safeinstallation.1.3 Functional Overview1.3.1 IntroductionThe Safe Torque Off (STO) function is a component in asafety control system. STO prevents the unit fromgenerating the power required to rotate the motor.NOTICESelect and apply the components in the safety controlsystem appropriately to achieve the desired level ofoperational safety. Before integrating and using STO inan installation, carry out a thorough risk analysis on theinstallation to determine whether the STO functionalityand safety levels are appropriate and sufficient.The VLT® frequency converter is available with:• Safe Torque Off (STO), as defined by EN IEC61800-5-2.• Stop Category 0, as defined in EN 60204-1.The frequency converter integrates the STO functionalityvia control terminal 37.The VLT® frequency converter with STO functionality isdesigned and approved suitable for the requirements of:• Category 3 in EN ISO 13849-1.• Performance Level "d" in EN ISO 13849-1.• SIL 2 in IEC 61508 and EN 61800-5-2.• SILCL 2 in EN 62061.1.3.2 Products Covered and IdentificationThe STO function is available for the following types offrequency converters:• VLT® HVAC Drive FC 102• VLT® Refrigeration Drive FC 103• VLT® AQUA Drive FC 202• VLT® AutomationDrive FC 301 enclosure size A1• VLT® AutomationDrive FC 302• VLT® Decentral Drive FCD 302• VLT® Parallel Drive ModulesIdentification• Confirm that the frequency converter isconfigured with STO function by checking theunit typecode on the nameplate (see Table 1.1).Product TypecodeVLT® HVAC Drive FC 102 T or U at digit 18 of thetypecodeVLT® Refrigeration Drive FC 103 T at digit 18 of the typecodeVLT® AQUA Drive FC 202 T or U at digit 18 of thetypecodeVLT® AutomationDrive FC 301enclosure size A1 T at digit 18 of the typecodeVLT® AutomationDrive FC 302 X, B, or R at digit 18 of thetypecodeVLT® Decentral Drive FCD 302 X, B, or R at digit 18 of thetypecodeVLT® Parallel Drive Modules T or U at digit 18 of thetypecodeTable 1.1 Typecode Identification1.4 Approvals and CertificationsMore approvals and certifications are available. Contact alocal Danfoss partner.Introduction Safe Torque Off2 Danfoss A/S © 01/2018 All rights reserved. MG37D50211