ABB ACH580-01 Series, Hardware Manual

Page: 351 / 396

Safe torque off function 351
Note: The voltage at the INx terminals of the drive must be at least 13 V DC to be
interpreted as “1”. The pulse tolerance of the input channels is 1 ms.

Grounding of protective shields
• Ground the shield in the cabling between the activation switch and the control
board at the control board.
• Ground the shield in the cabling between two control boards at one control board
only.
Operation principle
1. The Safe torque off activates (the activation switch is opened, or safety relay
contacts open).
2. The STO inputs of the drive control board de-energize.
3. The control board cuts off the control voltage from the output IGBTs.
4. The control program generates an indication as defined by parameter 31.22 (refer
to the firmware manual of the drive).
The parameter selects which indications are given when one or both STO signals
are switched off or lost. The indications also depend on whether the drive is
running or stopped when this occurs.
Note: This parameter does not affect the operation of the STO function itself. The
STO function will operate regardless of the setting of this parameter: a running
drive will stop upon removal of one or both STO signals, and will not start until
both STO signals are restored and all faults reset.
Note: The loss of only one STO signal always generates a fault as it is interpreted
as a malfunction of STO hardware or wiring.
5. The motor coasts to a stop (if running). The drive cannot restart while the
activation switch or safety 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 to start the drive.
Start-up including acceptance test
To ensure the safe operation of a safety function, validation is required. The final
assembler 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.