AKD™ Installation Manual - TG Drives

AKD Installation | 6 Technical description and data6.17 Safe Torque Off (STO)An additional digital input (STO) releases the power output stage of the drive as long as a 24 V signal isapplied to this input. If the STO input goes open-circuit, then power will no longer be supplied to the motor, andthe drive will lose all torque and coast to a stop.Input STO (X1/3)— Floating, reference ground is GND— 24 V ±10%, 20 mAThis input is not compatible with IEC 61131-2.You can thus achieve a restart lock-out for personnel safety by using the STO input in conjunction with anexternal safety circuit.Advantages of the restart lock STO:• The DC bus link remains charged up, since the mains supply line remains active.• Only low voltages are switched, so there is no contact wear.• Very little wiring is required.6.17.1 Safety instructionsIf the restart lock STO is automatically activated by a control system, then makesure that the output of the control is monitored for possible malfunction. Themonitoring can be used to prevent a faulty output from unintentionally activatingthe restart lock STO. Since the restart lock is a single-channel system, erroneousengaging will not be recognized.Use the following functional sequence when the restart lock STO is used:1. Brake the drive in a controlled manner (speed setpoint = 0 V).2. When speed = 0 rpm, disable the drive (enable = 0 V).3. If a suspended load is present, block the drive mechanically.4. Activate the restart lock STO.6.17.2 Use as directedDo not use the STO function until the functionality is approved. The (STO) inputis functional but is not independently certified. Kollmorgen is working on thefinal circuit design updates and will submit for formal SIL 2 STO certificationsoon. These updates will not change the wiring or functional operation.The restart lock STO is exclusively intended to provide safety for personnel by preventing the restart of a system.To achieve this personnel safety, the wiring of the safety circuits must meet the safety requirements ofIEC 60204, ISO 12100 and ISO 13849 category 3.The STO restart lock must only be activated when the motor is no longer rotating (setpoint = 0 V, speed = 0rpm, enable = 0 V).Drives with a suspended load must have an additional safe mechanical blocking(for instance, by a motor-holding brake). The drive cannot hold the load whenSTO is active. Serious injury could result when load is not propperly safed.54 Kollmorgen | December 2009