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KFU 2-/4-
12
1.8
Safety Instructions on Function „Safe Torque Off“ (STO)
The function „Safe Torque Off“ (STO) is a functional safety provision, i.e. it protects
staff from damage, provided that projecting, installation and operation are performed
properly. This function does not disconnect the plant from power supply.
To disconnect the plant from power supply (for example for service purposes) an
„Emergency Stop“ circuit according to EN 60204 has to be installed.
For maintenance work, a provision must be provided for disconnecting the plant from
power supply.
Warning!
Improper installation of the safety circuitry may result in uncontrolled
starting of the drive. This may cause death, serious injuries and signifi-
cant material damage.
Safety functions may only be installed and commissioned by qualified
staff.
The STO function is not suitable for emergency stop as per EN 60204.
An emergency stop can be realized by installing a mains contactor.
An emergency stop according to EN 60204 must be functioning in all
operation modes of the frequency inverter. Resetting of an emergency
stop must not result in uncontrolled starting of the drive.
The drive is started again when the function STO is no longer required.
In order to comply with EN 60204, it must be ensured by taking external
measures that the drive does not start without prior confirmation.
Without a mechanical brake, the drive will not stop immediately but
coast to a standstill. If this may result in personal or material damage,
additional safety measures must be taken.
If persons may be endangered after disconnection of the motor power
supply by STO, access to the hazard areas must be prevented until the
drive has stopped.
Check the safety function at regular intervals according to the results of
your risk analysis.
BONFIGLIOLI VECTRON recommends that the check is performed
after one year, at the latest.
The STO function is fail-safe. However, on rare occasions, the occur-
rence of component defects may cause jerking of the motor shaft (max.
180°/pole pair, e.g. jerk by 90° with 4-pole motor, 180°/2). It must be
checked if this causes a dangerous movement of the plant.
If the STO function is used, the special safety, installation and instruc-
tions on use instructions shall be complied with.