Achieving SIL 3 / PL e Safe Torque Off (STO) in industrial motor drives requires more than redundancy. It demands a safety architecture that can tolerate single faults, provide diagnostic coverage, and support a defensible safety case. In this webinar, we explore a practical dual-channel STO architecture that prevents torque-producing power from reaching the motor while meeting the architectural requirements of IEC 61800-5-2 and ISO 13849. We then examine how fault exclusion can be applied to isolation barriers, including insulation coordination, thermal limitation, and the system-level evidence needed to justify the exclusion and simplify STO safety analysis.

Attendees will:

  • Design SIL 3 / PL e STO architectures using dual-channel shutdown paths and diagnostics to ensure a single fault does not compromise the safety function.
  • Understand when fault exclusion can be claimed for isolation barriers and the two conditions required: proper insulation coordination and containment of internal faults. 
  • Apply ISO 13849 and IEC 61800-5-2 requirements to build a robust, standards-aligned safety argument that reduces PFH contribution and supports SIL 3 / PL e compliance.

Presenters

Declan Stuanton Principal Engineer, Product Applications
Senior Engineer, Product Applications