Use - ABB ACS880-107 Hardware Manual

166 The 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 inverter control unit de-energize, and the inverter control unit cuts
off the control voltage from the inverter IGBTs.
3. The control program generates an indication as defined by parameter 31.22 (refer to
the firmware manual of the inverter).
4. The motor coasts to a stop (if running). The inverter 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 inverter. Therefore maintenance work on
electrical parts of the inverter or the motor can only be carried out after isolating
the inverter from the main supply.
WARNING! The Safe torque off functionality is only achieved through the XSTO
connector of the inverter control unit. 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 firmware. It is
not supported by supply or brake firmware.
WARNING! (With permanent magnet or synchronous reluctance [SynRM] motors
only) In case of a multiple IGBT power semiconductor failure, the inverter system
can produce an alignment torque which maximally rotates the motor shaft by
180/p (with permanent magnet motors) or 180/2p (with synchronous reluctance [SynRM]
motors) degrees regardless of the activation of the Safe torque off function. p denotes the
number of pole pairs.
Notes:
•
If a running inverter is stopped by using the Safe torque off function, the inverter 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 inverter 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 inverter unit.
•
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.