ABB FSO-21, User Manual

Page: 33 / 540

Safety information and considerations 33
of the system (including drive and the motor) can only be carried out after a proper
isolating procedure, which must be obeyed to make sure that the maintained part of
the system is properly isolated.

Proof testing
Periodic proof testing of, for example, electromechanical parts of the safety system
may be required in order to maintain the claimed SIL / PL level of the system. In this
case proof testing must be taken into consideration in the safety calculations and it
must be properly documented in the user documentation. Proof testing has to be
verified in the acceptance testing during the commissioning phase.
The FSO module itself does not require periodic proof testing.
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. Do not do maintenance work on the
electrical parts of the drive or the motor before you isolate the drive system
from the main supply, from rotating permanent magnet motors, from rotating
motors equipped with sine filters and from all dangerous external voltages.
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 ACS880 drives with separate inverter, supply and brake units, the FSO module is
connected to the inverter unit(s). It cannot be connected to supply or brake units.