Safe Torque Off
vacon • 119
Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts/
9
9.5.2
Safety Capability Cat. 3 / PL
e
/ SIL 3
The safety capability is reduced to Cat. 3 / PL e / SIL 3 if the STO inputs are statically used (which
means they are forced to commute together).
Both STO inputs and the STO feedback have to be used. The same warnings and cabling instruction
as 9.5.1 apply.
9.5.3
Safety Capability Cat. 2 / PL
d
/ SIL 2
The safety capability is reduced to Cat. 2 / PL d / SIL 2 if the STO inputs are connected in parallel (no
redundancy of the STO inputs).
The STO feedback has to be used. The same warnings as 9.5.1 apply.The picture below shows an
example of connection for the STO function. The external device has to be connected with 4 wires
to the drive.
Figure 94. STO Example with automatic monitoring of the feedback and STO inputs connected
in parallel.
R
R
R
R
=
3
S1
G1
S2
G2
L1
L2
L3
F+
F-
U
V
W
DC+/R+
R-
DC-
Reinforced
POWER UNIT
EXTERNAL DEVICE
