Motor Fault — Bearing Temperature High

What This Fault Means

A bearing temperature alarm indicates the motor bearing housing temperature (measured by RTD or thermocouple) exceeded the warning threshold, typically 80°C (176°F) for standard bearings.

Common Causes

• Insufficient or degraded lubrication (grease dried out or wrong type)
• Over-greasing causing churning and heat buildup
• Bearing wear or spalling from fatigue
• Excessive belt tension or shaft misalignment increasing radial load
• Ambient temperature plus motor heat exceeding bearing rating

Recommended Fix

1. Check the grease condition — if dry or discolored, re-grease per the motor manufacturer's schedule and quantity.
2. Do NOT over-grease — use the calculated volume (V = 0.005 × D × B where D = OD, B = width in mm).
3. Listen for bearing noise with a stethoscope — rough, growling sound indicates damage.
4. Check shaft alignment and belt tension.
5. If the bearing is damaged (noise, excessive play), plan a replacement during the next scheduled downtime.