Safety Functions; Safe Torque Off (Sto) - Lenze i55AE125B Manual

13

Safety functions

13.1

Safe torque off (STO)

With this safety function, the drive can be switch off safely immediately.
DANGER!
Automatic restart if the request of the safety function is deactivated.
Possible consequences: Death or severe injuries
▶ You must provide external measures according to EN ISO 13849−1 which ensure that the
drive only restarts after a confirmation.
Preconditions
Inverter with I5MASA000 safety module
Details
Safe disconnection of the drive
1. A safety sensor requests the safety function.
2. The transmission of the pulse width modulation is safely switched off by the safety unit.
3. The power drivers do not generate a rotating field anymore.
4. The "STO is not active" status in the status word changes from 1: HIGH to 0: LOW (object
0x6041, bit 15).
The motor is safely switched to torqueless operation (STO).
Fig. 8: Operating principle of safety unit
X1 Control terminals of the safety unit
PWM Pulse width modulation
Truth table
Safe input / channel
SIA
0
0
1
1
If SIA and SIB are LOW at the same time, the internal status signal "Both STO
channels not active [155]" in the inverter is set to TRUE. This status signal can be
used to trigger a "non-safe output" (e.g. to the relay).
If the GS connection is interrupted or in case of a short circuit/short circuit of GS
to SIA/SIB, STO is active.
M Motor
µC Microcontroller
SIB Device status
0
1 STO active
0
1 Drive enabled
Safety functions
Inverter
Approval
0
0
0
1
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