51 TRIP ABB — LV Main Breaker Trip
At a glance
- Severity
- FAULT STOP
- Domain
- MV_SUBSTATION_SYSTEM
- Reference standard
- CEI 64-8 / IEC 61439-2
What it means
LV main breaker trip: immediate loss of an area or a chain. Find the cause before any re-arming.
Probable causes
- Downstream fault (short circuit, components)
- Protection grading lost (selectivity)
- Ungoverned real overload
- Degraded terminations with low-level fault currents
Where to start
Before re-arming: inspect the downstream board (smell, thermal marks, bus insulation measurements) and read the protection flag (overload or short circuit?).
Full guided diagnosis in the app
The diagnostic tree for this fault has 3 guided steps with measurements, checks and resolutions. You'll find it in DataCIQ, one of the five IndexOS apps: free, works offline.
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The same fault on other brands
More ABB codes
- FEEDER TRIP — Loss of One MV Feeder
- MV BREAKER TRIP — Total MV Supply Loss
- PHASE UNBALANCE — Phase Imbalance Upstream
- SPD END OF LIFE — SPD Cartridges Depleted
- WTI TRIP — Transformer Overtemperature / Insulation Fault
- 2310 — Overcurrent Fault
- 2330 — Ground Fault
- 3210 — DC Bus Overvoltage Fault