SEW-Eurodrive MOVIGEAR MGFx-DSI Series, Operating Instructions Manual

Page: 362 / 408

12
Functional safety
Integrated Safety Technology
Operating Instructions – MOVIGEAR
®
performance
362
12.2.3 Safety concept
The drive unit is supposed to be able to perform the drive safety function "Safe Torque
Off" according to EN 61800‑5‑2:
• The drive unit can be connected to an external safety controller or safety relay.
This external safety controller/safety relay disconnects the safety-related STO in-
put via a 2-pole 24 V switching signal (sourcing/sinking) when a connected com-
mand device (e.g. emergency stop button with latching function) is activated. This
activates the STO function of the drive unit.
• An internal, dual-channel structure with diagnostics prevents the generation of
pulse trains at the power output stage (IGBT).
• Instead of galvanic isolation of the drive from the supply system by means of con-
tactors or switches, the disconnection of the STO input described here safely pre-
vents the control of the power semiconductors in the output stage. The rotary-field
generation for the respective motor is deactivated even though the line voltage is
still present.
• When the STO drive safety function is activated, the PWM signals generated by
the drive unit are interrupted and not transmitted to the IGBTs.
• If the STO function detects a discrepancy between both channels, the PWM sig-
nals are inhibited. The inhibit can be revoked by a 24 V reset, or by a device reset
if F_STO_P1 and F_STO_P2 are not controlled with 24 V.
• The STO drive safety function can be activated externally e.g. via an external
safety device via the STO input.
25887548/EN – 04/2019