Motor Maintenance Checklist

1. General Safety

Apply LOTO (Lockout-Tagout) before starting work.
Use proper PPE: insulated gloves, goggles, safety shoes.
Verify motor is properly earthed/grounded.
Ensure working area is clean, dry, and ventilated.

2. Visual Inspection

Check for dust, dirt, oil, or moisture on motor housing.
Inspect motor casing for cracks, rust, or deformation.
Verify nameplate details (voltage, current, power rating).
Look for loose or missing bolts, nuts, or covers.
Inspect cooling fans and shrouds for damage.

3. Electrical Checks

Measure insulation resistance (IR test) with megger.
Perform polarization index (PI) test (for critical motors).
Check winding resistance balance between phases.
Verify terminal connections are tight and clean.
Check supply voltage and current balance (should be within ±5%).
Record power factor, efficiency, and load during operation.

4. Mechanical Checks

Inspect motor bearings for wear, noise, or overheating.
Lubricate bearings as per manufacturer’s schedule.
Check shaft alignment with driven equipment.
Inspect motor coupling/gearbox/belt drive condition.
Verify shaft end-play and radial play.

5. Cooling & Ventilation

Ensure air filters, ducts, and vents are clean.
Verify cooling fan direction and airflow.
Inspect cooling water/oil system (if applicable).
Check motor temperature rise (compare with nameplate limits).

6. Protection & Control

Verify overload relay settings.
Test motor protection devices (OC, EF, thermal relay).
Inspect contactors, relays, and control wiring.
Check starter (DOL/Star-Delta/VFD) operation.
Verify emergency stop function.

7. Vibration & Noise

Measure vibration levels with vibrometer.
Check for abnormal noise (bearing, shaft, or load-related).
Investigate unusual resonance or looseness.

8. Operational Checks

Start motor and monitor starting current.
Verify direction of rotation.
Check for smooth acceleration without jerks.
Monitor motor under full load for stability.

9. Maintenance Frequency

Daily: Cleanliness, noise, temperature, load readings.
Monthly: IR test, lubrication check, vibration check.
Quarterly: Bearing inspection, relay tests, thermography.
Yearly: Full electrical + mechanical overhaul, winding resistance, PI test.