Safety Instructions On Function „Safe Torque Off" (Sto) - BONFIGLIOLI Vectron ACTIVE CUBE Applications Manual

3 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.
The safety function "Safe torque off" (STO) can be used to realize an "Emergency
Stop" according to EN 60204 while the power supply is still active on the frequency
inverter
A provision must be provided for disconnecting the machine from power supply for
maintenance work.
WARNING
Improper installation of the safety technique can cause an uncontrolled starting of the
drive. This may cause death, serious injuries and significant material damage.
Safety functions may only be installed and commissioned by qualified staff.
The Standard EN 60204 separates EMERGENCY SWITCH OFF and EMERGENCY STOP.
EMERGENCY SWITCH OFF means the electrical disconnection of the frequency invert-
er from the supply source. An EMERGENCY SWITCH OFF can be realized by installing
a switch disconnector in example.
EMERGENCY STOP provides the possibility to achieve a safe state of the frequency
inverter while maintaining the supply voltage.
Depending on the application, other components may be necessary to achieve a safe
state in addition to "Safe Torque Off (STO)" of the frequency inverter.
An EMERGENCY STOP according to EN 60204 must be functioning in all operation
modes of the application.
Resetting of an EMERGENCY STOP or an EMERGENCY SWITCH OFF must not result in
uncontrolled starting of the drive.
The drive is started again when the function STO is no longer triggered. 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 might 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 control by STO, ac-
cess 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
assessment. BONFIGLIOLI VECTRON recommends that the check is performed after
one year, at the latest.
The STO function is one fault fail-safe. No single fault or component failure can cause
a disabled drive to produce motor shaft torque. Only in extremely unlike combinations
of component faults the motor shaft could move jerky with sudden acceleration (max-
imum 180°/number of pole pairs, for example jerky movement of 90° for 4-pole mo-
tor, 180°/2) and produce torque. It must be checked if this behavior can cause a
dangerous machine movement.
If the STO function is used, the special safety, installation and instructions on use
instructions shall be complied with.
Comply with the Application manual „Safe Torque Off STO", especially when the de-
scribed safety relevant function is used.
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