Implemented Safety Functions; Safe Torque Off (Sto) - WEG CFW900 Serie Manual De Seguridad

Safety

1.2 IMPLEMENTED SAFETY FUNCTIONS

When equipped with the STO90 safety functions board, the CFW900 frequency inverter is able
to perform two standardized safety stopping functions:
1. Safe torque off (STO) according to IEC 61800-5-2 or stop category 0 according to IEC
60204-1.
2. Safe stop 1 time controlled (SS1-t) according to IEC 61800-5-2 or stop category 1 according
to IEC 60204-1.
ATTENTION!
Even when the safety stop function is active, dangerous voltage levels may
be present in the motor. Thus, before any intervention on electrical parts, the
system must be completely de-energized.
ATTENTION!
In applications where external influences are relevant (e.g. fall of suspended
loads), additional measures (e.g. use of mechanical brakes) may be necessary
to prevent any hazard. The risk analysis must be performed by the end user
in order to identify and cover all possible hazards and risks in the application.
NOTE!
The safety stop functions should not be used as a control for starting and/or
stopping the motor.
NOTE!
The safety functions take priority over all other functions of CFW900.
NOTE!
The safety of the entire system depends on the final certification of the
equipment where CFW900 is applied. WEG is not liable for damages and/or
losses during the use of the CFW900. Thus, WEG cannot be held liable for
applications based on figures and examples presented in this manual, which
are used for illustrative purposes only.

1.2.1 Safe Torque Off (STO)

The STO safety function acts on the removal of torque from the motor, i.e. no power that can
generate torque is present on the motor after activating this function. The difference between
STO and other ways to stop the motor is that the former does it with very high levels of reliability
against unexpected motor starts, even under a fault conditions - refer to
DATA on page 10.
8 | CFW900
Section 1.3 SAFETY