What you'll learn
**Reported symptom:** The control supply is healthy and Start works mechanically, but KM1 cannot energise.
Lab time: ~12 minutes.
Lesson briefing
Thermal Overload Trip
Reported symptom: The control supply is healthy and Start works mechanically, but KM1 cannot energise.
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
Trace the series control chain and find which normally closed protective contact is open.
Choose the fault category only when the measurements support it.
Hints
Measure voltage to each side of Stop and then OL terminals 95 and 96.
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This lesson uses 11 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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