Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
GE Multilin Protective Relay Fault Codes — Quick Reference
GE Multilin relays (369 Motor Management, 489 Generator, 750/760 Feeder, 850 Motor, and UR Series) record trip events with cause codes that appear on the display and in the event log via the EnerVista software.
| Element | Protection Function | Common Trip Cause |
|---|---|---|
| 50 — Instantaneous Overcurrent | High magnitude fault current | Short circuit on protected equipment |
| 51 — Time Overcurrent | Sustained overcurrent | Overload or slow fault |
| 46 — Negative Sequence | Phase unbalance | Open phase or unbalanced load |
| 49 — Thermal Model | Thermal limit exceeded | Motor overloaded, stalls, or hot |
| 27 — Undervoltage | Voltage below threshold | Supply problem or voltage sag |
| 59 — Overvoltage | Voltage above threshold | Supply transient or regulator issue |
| 87 — Differential | Current mismatch across zone | Internal fault in transformer or motor |
| 67 — Directional OC | Fault current in wrong direction | Reverse power or backfeed |
Most Common Trips
Element 49 — Thermal Model Trip (369/850)
The GE Multilin 369 Motor Management Relay models motor thermal state using measured current. A thermal trip means the motor reached its modeled thermal limit. Check: Was the motor subjected to multiple consecutive starts? Did it run overloaded? Allow adequate cooling time (check the relay’s thermal capacity remaining on the display) before restart.
Element 50/51 — Overcurrent Trip
Check the event log for the fault current magnitude. A 50 (instantaneous) trip indicates a high-magnitude fault. A 51 (time overcurrent) indicates sustained overcurrent. Use the trip magnitude to narrow the fault location — a high magnitude 50 trip likely indicates a fault close to the relay; a lower value 51 indicates a more distant or sustained overload condition.
Element 46 — Negative Sequence
Open-phase conditions, blown fuses, or severe load imbalance create negative sequence current. Check all three phase fuses and confirm all three phases are present and within 2% voltage balance.
Reading the Event Log
Use the front panel display or EnerVista software:
- Navigate to ACTUAL → EVENT LOG
- View the most recent trip: element, timestamp, and measured values at time of trip
- Compare to settings to verify the trip was appropriate
Parts / Actions Often Needed
| Action | Notes |
|---|---|
| Reset trip | Front panel RESET after fault cleared |
| EnerVista software | Required for full event log and settings |
| CT secondary check | Verify CT ratios match relay settings |
| Firmware update | If relay displays self-diagnostic fault |
Need Replacement Parts?
Before ordering, match the commercial equipment part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Jump to Fix
- Thermal (49) trip → Check thermal capacity on display → Allow cooling → Investigate overload
- 50/51 OC trip → Record trip current from event log → Locate fault → Clear before reset
- 46 unbalance → Check all three phases → Inspect fuses → Correct load imbalance
When to Call a Pro
Protective relay settings (coordination studies, time-current curves) should be performed by a licensed protection engineer. GE Multilin service is available for firmware, calibration, and repair.