9
vacon • 77
Safe Torque Off
9.6
Commissioning
9.6.1
General wiring instructions
The wiring should be done according to the general wiring instructions for the specific product. A
shielded cable is required. In addition, the voltage drop from the supply point to the load shall not
exceed 5% [EN 60204-1 part 12.5].
The following table indicates examples of cables to be used.
9.6.2
Checklist for the commissioning
Follow the checklist of the table below with the steps required to use the STO function.
Protect the STO cabling with a shielding or an enclosure to exclude external fault.
Wires ferrules are highly recommended for all STO signals (inputs and feedback).
STO feedback
Cable size
STO feedback automatically
monitored by an external safety
device
3 x (2 + 1) x 0,5 mm
2
(*)
STO feedback ignored, simply
safety device (switch) used
2 x (2 + 1) x 0,5 mm
2
Table 35. Cable types required to meet the standards. (*) Additional wires are needed for
restarting the drive after each STO demand.
Carry out a risk assessment of the system to ensure that the use of the STO function is
safe and according to the local regulations
Include in the assessment an examination of whether the use of external devices, such
as a mechanical brake, is required.
Check if the switch (if used) has been chosen according to the required safety perfor-
mance target (SIL/PL/Category) set during the risk evaluation
Check if the external device for automatic monitoring of the STO output feedback (if
used) has been chosen in accordance with the specific application
Check if the reset function with the STO function (if used) is edge sensitive.
The shaft of a permanent magnet motor might, in an IGBT fault situation, still provide
energy before the torque production ceases. This may result in a jerk of max. 180° elec-
trically. Ensured that the system is designed in such a way that this can be accepted.
Check if the degree of protection of the
enclosure is at least IP54.
See paragraph 9.5.
Check if the recommendations on EMC for cables have been followed.
Check if the system has been designed in such a way that enabling of the drive through
STO inputs will not lead to an unexpected start of the drive
Check if only approved units and parts have been used.
Set up a routine to ensure that the functionality of the STO function is being checked at
regular intervals.
Table 36. Checklist for the commissioning of STO.
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