STO (Safe Torque Off) is the fundamental safety function that safely removes the energy a drive would use to produce torque. When STO is active, the motor coasts down.
Key distinctionSTO does not STOP the motor; it only prevents torque generation. For a controlled stop, SS1 (Safe Stop 1) is used.
How it works
STO typically removes the gate-driver supply via two independent channels (redundancy). A channel mismatch raises a safety fault.
- Stop category
- Cat. 0 (coast down)
- Typical level
- SIL 2 / PL d
After commissioning STO, a validation test must be performed and documented.
Related Faults
Related Topics
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