PM planOfficial FreeMaint

Electric motor six-monthly preventive maintenance plan

Six-monthly plan for a low-voltage induction motor: vibration, temperatures and phase currents checked running, cooling fins cleaned, bearings greased where regreasable, and a yearly check of the terminal box and of the winding insulation.

9 tasksMotors and rotating machineryVersion 1Updated

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What’s inside

Schedule

Every 6 months

  • Fixed calendar: the next date does not move with the completion date.
  • Work order window: 14 days
Estimated duration: 1 h 15 minPriority: Medium

Imported inactive and without equipment: assign it to your assets, set its start date (the first due date), check the intervals against the manufacturer’s manual, then switch it on.

Tasks at each service

  1. Measure vibration at both bearings

    With the motor running at its usual load, measure overall velocity vibration in mm/s at the drive-end and non-drive-end bearings, in the same points and directions as the baseline. Listen for bearing noise at the same time.

    Measurement15 min

    Tools: Vibration meter

    Risks: Rotating shaft and coupling: keep every guard in place during the measurement.

  2. Measure the frame and bearing temperatures

    Measure the surface temperature of the frame and of each bearing housing and look for a rise against the previous readings.

    Measurement5 min

    Tools: Infrared thermometer

  3. Measure the current on each phase

    Measure the running current of the three phases and compare it with the full-load current on the nameplate and with the previous readings. A current above the nameplate value, or a growing difference between phases, points to an overload, a supply imbalance or a winding fault.

    Measurement10 min

    Tools: Clamp meter

    Risks: Measure at the cables only, with the enclosure closed or with the protection required for work near live parts.

  4. Clean the cooling fins and the fan cover

    Motor stopped, remove dust and deposits from the frame fins and the fan cover inlet, check that the fan is intact and that nothing restricts the airflow around the motor.

    Action20 min

    Risks: Isolate and lock out the motor before removing the fan cover. Never blow compressed air towards the bearings or the terminal box.

  5. Grease the bearings (regreasable bearings only)

    Apply the grease type and quantity given on the nameplate or in the manual, with the drain plug open so the old grease can escape; never over-grease. Skip this task on bearings sealed for life.

    Action15 minoptional

    Tools: Grease gun

  6. Check the mounting, the coupling or belt guard and the base

    Check that the foot bolts are tight, the base shows no crack, and the coupling or belt guard is complete and fixed.

    Inspection10 min

  7. Inspect the terminal box

    Check that the connections are tight and show no sign of overheating, the cable gland and the cover gasket are intact, and the earth (ground) connection is in place.

    Inspection20 minonce every 2 services

    Risks: Isolate, lock out and verify the absence of voltage before opening the terminal box.

  8. Test the winding insulation resistance

    Motor isolated and its cables disconnected from any variable speed drive, test each phase to earth with the DC test voltage suited to the motor voltage, then discharge the windings. Record the value with the winding temperature and compare it with the previous tests: a falling trend matters more than one value.

    Measurement30 minonce every 2 services

    Tools: Insulation resistance tester

    Risks: Isolate, lock out and verify the absence of voltage. Never test through a variable speed drive. Discharge the windings after each test.

  9. Restart, check and record the readings

    Remove the locks, restart the motor and check its direction of rotation and noise. Record every value in the work order and report anything that needs a corrective action.

    Verification5 min

Parts (indicative)

  • Bearing grease cartridge, type per nameplate × 1

Tools (indicative)

  • Vibration meter
  • Infrared thermometer
  • Clamp meter
  • Insulation resistance tester — Yearly insulation test
  • Voltage tester
  • Grease gun

Indicative list: on import it is written into the plan’s description, to link to your own inventory.

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Licence

Official FreeMaint template, free to use and adapt inside your FreeMaint workspace. An adaptation may be shared in the library under CC BY 4.0; its page then credits this template.

Templates are general guidance. They do not replace the manufacturer’s instructions, your site procedures or applicable regulations.

Equipment: Motors and rotating machinery

Industries: Manufacturing, Energy and utilities, Facilities, Food and beverage

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