And rolled out at 2:30 a.m. for a “stuck” 69 kV breaker and it closed like a champ the second my Doble cart hit the gravel, as if the trip coil suddenly found religion. SCADA swore trip coil fail for an hour, but on site both coils sat pretty at 12.6 ohms and the relay log looked cleaner than a new PT. What other pieces of gear start behaving the moment you show up with a wrench?
Had one at 3 a.m. where SCADA screamed ‘trip coil fail’ for an hour, coils sat at 12.6 ohms like yours, and it magically behaved once the Doble cart rolled up; turned out a crusty RTU input terminal was barely making, so the alarm stuck while the breaker was fine. If it happens again, clip a recorder across the 125 Vdc at the coil and give the marshalling cabinet terminations a firm tug — night-cold loosies are sneakier than bad coils.
Seen the same 69 kV magic — “trip coil fail” until the Doble cart rattled in — turned out to be a sticky 52b in the marshalling cab that only made once the cabinet warmed a touch. Coils read 12.6 ohms like yours, but we caught a 5–6 V sag on the 125 VDC when the trip-circuit monitor pulsed it. If it’s not the aux, check the knife switch and RTU wetting current on that input, @BreakerWhisperer.
Had a ‘quantum breaker’ that only behaved when I cracked the door; turned out the 86 lockout’s seal‑in contact had a light film — heat and vibration made it pass, so we carded it and bumped the DI wetting voltage and it quit. If you go back, meter the close path under load and wiggle the 86/anti‑pump wiring while the RTU log is rolling to catch it in the act. If that’s clean, I’ve also seen a flaky battery ground detector drag the control bus just enough to fake an alarm.