242 Safe Torque off functionOperation principle1. The Safe torque off activates (the activation switch is opened, or safety relaycontacts open).2. The STO inputs on the drive control unit de-energize.3. The control unit cuts off the control voltage from the drive IGBTs.4. The control program generates an indication as defined by parameter 31.22 (referto the firmware manual of the drive).5. Motor coasts to a stop (if running). The drive cannot restart while the activationswitch or safety relay contacts are open. After the contacts close, a new startcommand is required to start 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 acceptancetest.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 personwith adequate expertise and knowledge of the safety function as well as functionalsafety, as required by IEC 61508-1 clause 6. The test procedures and report must bedocumented and signed by this person. Acceptance test reportsSigned acceptance test reports must be stored in the logbook of the machine. Thereport shall include documentation of start-up activities and test results, references tofailure reports and resolution of failures. Any new acceptance tests performed due tochanges or maintenance 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 or Q973, do the procedureshown in the FSO module documentation. If an FSO-xx safety functions module or anFPTC-0x module is installed, refer to its documentation.
