ABB ACS880-07LC, Hardware Manual

Page: 211 / 222

Use
1. Open the activation switch, or activate the safety functionality that is wired to the STO
connection.
2. The STO inputs on the drive control unit de-energize, and the control unit cuts off the
control voltage from the output IGBTs.
3. The control program generates an indication as defined by parameter 31.22 (see the
firmware manual of the drive).
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 resetting 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
supply and all other voltage sources.
WARNING!
The Safe torque off functionality is only achieved through the XSTO connector of
the inverter control unit (A41). True Safe torque off functionality is not achieved
through the XSTO connectors of other control units (such as the supply control
unit or the brake control unit).
The Safe torque off function is supported by any ACS880 inverter or drive control
program. It is not supported by supply, DC/DC converter or brake firmware.
WARNING!
(With permanent magnet or synchronous reluctance [SynRM] motors only)
In case of a multiple IGBT power semiconductor failure, the drive can produce an
alignment torque which maximally rotates the motor shaft by 180/
p degrees (with
permanent magnet motors) or 180/2 p degrees (with synchronous reluctance
[SynRM] motors) regardless of the activation of the Safe torque off function. p
denotes the number of pole pairs.
Notes:
• If a running drive is stopped by using the Safe torque off function, the drive will cut off
the motor supply voltage and the motor will coast to a stop. If this causes danger or is
not otherwise acceptable, stop the drive and machinery using the appropriate stop mode
before activating the Safe torque off function.
• The Safe torque off function overrides all other functions of the drive.
• The Safe torque off function is ineffective against deliberate sabotage or misuse.
• The Safe torque off function has been designed to reduce the recognized hazardous
conditions. In spite of this, it is not always possible to eliminate all potential hazards.
The assembler of the machine must inform the final user about the residual risks.
The Safe torque off function 211