vacon • 30 STO AND SS1 SAFETY FUNCTIONS
Local contacts: https://www.danfoss.com/en/contact-us/contacts-list/
Figure 15. Structure of cable with two individually shielded twisted pairs
X = Not recommended due to causes of electromagnetic disturbances, safety actuator configuration or behavior in failure
situations.
3.5.2 Checklist for commissioning the OPTAF board
The minimum steps required during connecting the Safe Torque Off (STO) or Safe Stop 1 (SS1) safe-
ty functions of the OPTAF board are shown in the checklist below. To comply with the functional
safety standards, each point of the checklist must be answered yes. For ATEX related issues see the
ATEX section.
Table 6. Recommended maximum cable lengths
Safety actuator type
Diagnostics on safety
actuator
Cable type
Used STO input connection
STO
connection
example 1
STO
connection
example 2
STO
connection
example 3
Undiagnosed safety actuator
(i.e. emergency stop button or
relay contact)
No diagnostics
Shielded X 200 m 200 m
Unshielded X 30 m X
Safety actuator with diagnosed
outputs (i.e. safety PLC)
Outputs diagnosed using
e.g. dark test pulse,
light test pulse not used
Shielded 200 m 200 m 200 m
Unshielded 30 m 30 m X
Outputs diagnosed using
light test pulse
Shielded 200 m X X
Unshielded 30 m X X
Table 7. Checklist for commissioning the STO or SS1 safety functions.
Nr Step No Yes
1
Has a risk assessment of the system been carried out to ensure that
using the OPTAF board Safe Torque Off (STO) or Safe Stop 1 (SS1) safety
function is safe and according to local regulations?
2
Does the assessment include an examination of whether using external
devices such as a mechanical brake is required?
Individual pair Overall shield
(Optional)
Pair shield
Cable jacket
11860_uk
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