During a routine inspection, you notice a significant amount of grease leaking from the shaft of a 550 V, 3-phase motor. The motor is running, but the grease is discoloured and has a burnt smell. What action should be taken?

Question: During a routine inspection, you notice a significant amount of grease leaking from the shaft of a 550 V, 3-phase motor. The motor is running, but the grease is discoloured and has a burnt smell. What action should be taken?

Answer options: ✅ Shut down the motor immediately and investigate the bearings.

• Monitor the motor for increased vibration or temperature changes.
• Wipe away the excess grease and continue operation, scheduling maintenance for later.
• Add more grease to the bearing to compensate for the leakage.

Correct answer: Shut down the motor immediately and investigate the bearings.

Explanation: Grease leaking from a motor shaft, especially if discoloured and burnt, is a strong indication of overheating bearings. This can be caused by over-greasing, bearing failure, or excessive mechanical load. Continuing to operate the motor risks catastrophic bearing failure, damage to the motor windings, and potential safety hazards. Immediate shutdown and investigation are critical. Simply adding more grease or monitoring alone is inadequate and potentially unsafe.