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Three Phase LV Induction Motor – 6-Month Maintenance Checklist

Learn how to apply Complete Checklist for a Low Voltage Three Phase Induction Motor Periodic Maintenance

Here is a Complete Checklist for a Low Voltage Three Phase Induction Motor Periodic Maintenance


⚠️ Pre-Maintenance Safety Steps (Mandatory)

  • Isolate power from substation drawer

  • Apply Lockout/Tagout (LOTO) at substation

  • Isolate local station controller

  • Verify zero energy state using a voltage tester

  • Wear appropriate PPE

🔍 1. Visual Inspection

  • Check for physical damage: housing, terminal box, cooling fins, fan cover, and cable gland

  • Inspect for signs of overheating, corrosion, dirt buildup, or oil leaks

  • Check wiring for loose connections or discoloration

🔧 2. Retightening Connections

  • Open terminal box and verify tightness of all terminals

  • Retighten if looseness or oxidation is observed

🔌 3. Continuity & Phase Resistance Test

Tool: Digital Multimeter
Procedure:

  • Remove connection bars (U–V–W)

  • Measure continuity across windings (U–V–W)

  • Measure resistance across each phase (U–V, V–W, U–W)

  • Confirm resistance values are within ±10% of each other

  • Record measured values:

Phase PairMeasured Resistance (Ω)
U – V
V – W
U – W

⚡ 4. Insulation Resistance Test

Tool: Megger (500V or 1000V)
Procedure:

  • Ensure motor is completely disconnected and discharged

  • Measure resistance between windings and earth (U-E, V-E, W-E)

  • Measure resistance between phases (U–V, V–W, U–W)

  • Acceptable value: > 1 MΩ

  • Record values:

Test PointMeasured Resistance (MΩ)
U – E
V – E
W – E
U – V
V – W
U – W

🌍 5. Earth Resistance Testing

Tool: Clamp Earth Tester

  • Measure and record earth resistance value:
    Measured Earth Resistance: ___________ Ω

  • Confirm it is within site standard limits (typically < 5 Ω)

🧠 6. Substation Drawer – Protection & Control Circuit Test

  • Test motor overload relays and contactors

  • Verify trip settings according to motor full-load current

  • If safe, simulate fault conditions to test protection response

  • Check control circuit logic and interlocks

🔓 7. Post-Maintenance Reconnection

  • Remove all locks/tags only after verification

  • Reconnect terminals and control wiring properly

  • Restore power and test run motor

  • Observe for abnormal noise, vibration, or heat

🧴 8. Lubrication

  • Check motor manufacturer’s grease schedule

  • Apply correct grease type if needed

  • Wipe off excess and seal grease nipple

🌡️ 9. Temperature and Thermal Scan (Optional if Loaded)

Tool: Infrared Thermal Camera

  • Scan motor surface, bearings, and terminal box

  • Record any hot spots or abnormal temperatures

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