ABB FSO-12, User Manual

Page: 35 / 388

Safety information and considerations 35
External contactors, relays and mechanical actuators must be sized correctly for
safety use as the automatic diagnostics only monitors the electrical connections; the
mechanical final elements like brakes are not diagnosed.
Failure of a mechanical actuator, for example a brake, could lead up to an undetected
fault, and a possible loss of the load control.

Safety separation
The FSO module and the drive Safe torque off (STO) channel/function are safety
relevant, and the rest of the drive is considered as not safety relevant, for example,
the drive regular I/O cannot be used for requesting safety functions on the FSO.
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 system from the main supply, from rotating permanent magnet motors and from
rotating motors equipped with sine filters; asserting the STO is not sufficient.
Note: The Safe torque off function can be used for stopping the drive in the
operational mode. If a running drive is stopped by using the STO function, the drive
stops by coasting.

ACS880 drives with separate inverter and supply units
In the ACS880 multidrives and high power ACS880-07/17/37 single drives, there are
separate inverter, supply and brake units. The FSO module is connected to the
inverter unit. It cannot be connected to supply or brake units.