240 Safe torque off function
Use
1. Open the activation switch, or activate the safety functionality that is wired to the
STO connection.
2. STO inputs on the drive control board de-energize, and the drive control board
cuts off the control voltage from the output IGBTs.
3. The control program generates an indication as defined by parameter 31.22 STO
indication run/stop (see the drive firmware manual).
4. The motor coasts to a stop (if running). The drive will not restart while the
activation switch or safety relay contacts are open.
5. Deactivate the STO by closing the activation switch, or reseting the safety
functionality that is wired to the STO connection.
6. Reset any faults before restarting.
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 from the DC supply.
Test the operation of the failure detection of the drive. The motor can be stopped or
running.
• Open the 1st channel of the STO circuit. If the motor was running, it should coast to
a stop. The drive generates a FA81 Safe Torque Off 1 loss fault indication (see the
drive firmware manual).
• Give a start command to verify that the STO function blocks the drive’s operation.
The motor should not start.
• Close the STO circuit.
• Reset any active faults. Restart the drive and check that the motor runs normally.
• Open the 2nd channel of the STO circuit. If the motor was running, it should coast
to a stop. The drive generates a FA82 Safe Torque Off 2 loss fault indication (see
the drive firmware manual).
• Give a start command to verify that the STO function blocks the drive’s operation.
The motor should not start.
• Close the STO circuit.
• Reset any active faults. Restart the drive and check that the motor runs normally.
Document and sign the acceptance test report which verifies that the safety function is
safe and accepted for operation.
Action
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