Safe torque off function 223Operation principle1. The Safe torque off activates (the activation switch is opened, or safety relay contactsopen).2. STO inputs on the drive control unit de-energize.3. The control unit cuts off the control voltage from the output IGBTs.4. The control program generates an indication as defined by parameter 31.22 (refer tothe firmware manual of the drive).5. Motor coasts to stop (if running). The drive cannot restart while the activation switch orsafety relay contacts are open. After the contacts close, a reset may be needed(depending on the setting of parameter 31.22), A new start command is required tostart the drive.Start-up including acceptance testTo ensure the safe operation of a safety function, validation is required. The finalassembler of the machine must validate the function by performing an acceptance test.The acceptance test must be performed• at initial start-up of the safety function• after any changes related to the safety function (circuit boards, wiring, components,settings, etc.)• after any maintenance work related to the safety function. CompetenceThe acceptance test of the safety function must be carried out by a competent person withadequate expertise and knowledge of the safety function as well as functional safety, asrequired by IEC 61508-1 clause 6. The test procedures and report must be documentedand signed by this person. Acceptance test reportsSigned acceptance test reports must be stored in the logbook of the machine. The reportshall include documentation of start-up activities and test results, references to failurereports and resolution of failures. Any new acceptance tests performed due to changes ormaintenance shall be logged into the logbook. Acceptance test procedureAfter wiring the Safe torque off function, validate its operation as follows.Note: If the drive is equipped with safety option +Q972, +Q973 or +Q982, do theprocedure shown in the FSO module documentation. If an FSO-xx safety functionsmodule or an FPTC-0x module is installed, refer to its documentation..ActionWARNING! Obey the safety instructions in chapter Safety instructions. If you ignore them,injury or death, or damage to the equipment can occur.Ensure that the drive can be run and stopped freely during start-up.Stop the drive (if running), switch the input power off and isolate the drive from the power line by adisconnector.
