What you'll learn
Integrate a dual-channel guard switch, safety relay and VFD Safe Torque Off inputs. Add the ordinary run command and hardwired running/fault feedback to a PLC. STO removes motor-producing torque; it does not isolate the drive’s mains or DC bus.
Lab time: ~25 minutes.
Lesson briefing
VFD Safe Torque Off and Status Feedback
Integrate a dual-channel guard switch, safety relay and VFD Safe Torque Off inputs. Add the ordinary run command and hardwired running/fault feedback to a PLC. STO removes motor-producing torque; it does not isolate the drive’s mains or DC bus.
Why it is wired this way
Both STO channels must be independently controlled and monitored. The normal run command cannot be part of the safety function. Maintenance still requires lockable mains isolation and proof of dead.
Commissioning standard
Before energising, prove protective earth and continuity, verify the drawing terminal-by-terminal, then energise through the protective device and measure the expected supply, signal and return values. Never use this training panel as a substitute for the machine manufacturer’s instructions, risk assessment, isolation procedure or applicable electrical standard.
Hints
Wire the guard switch OSSD channels to separate safety relay inputs.
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This lesson uses 9 placed components on the lab canvas. Components are vendor-neutral (no proprietary trademarks); the wiring rules apply to any equivalent industrial part.
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