What you'll learn
**Reported symptom:** The light curtain is interrupted, yet the contactor coil path remains continuous.
Lab time: ~14 minutes.
Lesson briefing
Welded Safety Output Contact
Reported symptom: The light curtain is interrupted, yet the contactor coil path remains continuous.
The circuit was commissioned from a known-good drawing. Treat every terminal as suspect, but test from source to load instead of guessing. Use voltage mode on an energised control circuit and continuity only after the simulated circuit is isolated.
Your task
Isolate the panel and prove whether KSR1 output 13–14 actually opens when the safety relay drops.
Choose the fault category only when the measurements support it.
Hints
First confirm both OSSD inputs change state so the fault is not at the curtain.
Sign up to unlock the full hint sequence.
Sign up to unlock the full hint sequence.
Sign up to unlock the full hint sequence.
This lesson uses 7 placed components on the lab canvas. Components are vendor-neutral (no proprietary trademarks); the wiring rules apply to any equivalent industrial part.
Sign up to preview
Create a free account to preview this Pro lab; upgrade to open the interactive circuit.
Sign up to preview →