Technical data

54
Safe torque off (STO)
The safety function “Safe Torque Off” (STO) with
the safety integrity level SIL 2 (see DIN EN 61508
and DIN IEC 61800-5-2) is implemented into
standard Active Cube inverter range.
The drive feature helps overall automation system
to achieve “Safe Stop“ category 3, according to
DIN EN 954-1.
Thanks to STO function, energy supply from
frequency inverter to motor is safely disabled.
Deactivation of the inverter supply is carried out
via two switch off paths in no-signal current mode,
thus performing redundant switch off control.
Continuous monitoring tests are done by the
inverter to detect possible control failures.
“Safe Torque Off“ function greatly improves safety
level of your automation system without the need
of additional components.
Safety Control
K
M
Off 2
Mains
Off 1 Integrated
safety function
Safety Control
K
M
Off 1 Off 2
Mains
Without STO
With STO