Safety Instructions For "Safe Torque Off" Function (Sto) - BONFIGLIOLI ACTIVE CUBE Série Guide Rapide

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Safety instructions for "Safe torque off" function (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 machine
from power supply.
According to EN 60204 a provision must be provided for disconnecting the machine from power supply for
maintenance work.
For personal safety and to prevent material damage comply with the following instructions.
Warning!
• Improper installation of the safety technique can cause an uncontrolled starting of the drive. This
can result in death, serious injury or material damage.
• Only qualified staff may install and commission the safety functions.
• 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 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 stanstill. 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, access to the hazard
areas must be prevented until the drive has stopped.
• Check the safety function in periodic maintenance according to your risk assessment. BONFIGLIOLI
VECTRON recommends an inspection latest after one year.
• 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 mo-
tor shaft could move jerky with sudden acceleration (maximum 180°/number of pole pairs, for ex-
ample jerky movement of 90° for 4-pole motor, 180°/2) and produce torque. It must be checked,
if this behaviour 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.
Warning! Dangerous voltage!
The safety function "Safe torque off" is practical only for mechanical work on driven machines, but not
for work on live-line voltage-carrying components.
• After disconnection of an external DC 24 V power supply, the DC link of the frequency inverter is
still connected to mains supply.
• Even if the motor control is deactivated and the motor is coasting to a standstill or has already
stopped, high voltages may still be present on the motor terminals.
• Before working (e.g. maintenance) on live parts, the machine must al-ways be disconnected from
mains supply (main switch). This must be documented on the machine.
• When the function "Safe Torque Off" is triggered, the motor is not isolated from the DC link of the
frequency inverter. High voltage levels may be present at the motor.
• Do not touch voltage-carrying contacts.
Note:
According to the EU Machinery Directive 98/37/EG the machine must be subjected to a risk assess-
ment, carried out by the manufacturer. In this assessment the effect of the safety features in the
control system will be taken into account when looking at the overall risk of each possible hazardous
event. Standard EN 14121-1 - Safety of machinery - Risk assessment - Part 1: Principles - describes the
information which is necessary for risk assessment.
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