Maintenance; Fault Tracing - ABB ACS560 Hardware Manual

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 main
supply.
WARNING!
(With permanent magnet motors only). In case of a multiple IGBT power
semiconductor failure, the drive system can produce an alignment torque which
maximally rotates the motor shaft by 180/p degrees (with permanent magnet
motors) regardless of the activation of the Safe torque off function. p denotes the
number of pole pairs.
Note:
• 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 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.

Maintenance

After the operation of the circuit is validated at start-up, the STO function should be
maintained by periodic proof testing. In high demand mode of operation, the maximum proof
test interval is 20 years. In low demand mode of operation, the maximum proof test interval
is 2 years. The test procedure is given in section
In addition to proof testing, it is a good practice to check the operation of the function when
other maintenance procedures are carried out on the machinery.
Include the Safe torque off operation test described above in the routine maintenance
program of the machinery that the drive runs.
If any wiring or component change is needed after start up, or the parameters are restored,
follow the test given in section
Use only spare parts.

Fault tracing

The indications given during the normal operation of the Safe torque off function are selected
by parameter .
The diagnostics of the Safe torque off function cross-compare the status of the two STO
channels. In case the channels are not in the same state, a fault reaction function is
performed and the drive trips on an "STO hardware failure" fault. An attempt to use the STO
Acceptance test procedure (page 154)
Acceptance test procedure (page
Safe torque off function 155
154).