Run Transformer Insulation Resistance (Megger) Test — Free

Inspection Details

Asset identification recorded

Record transformer ID, location, nameplate rating, and serial number.

Inspection date and time recorded

Document when the insulation resistance test was performed.

Inspector name and qualification recorded

Record the technician or electrician performing the test and their qualification or certification if applicable.

Work order or test reference recorded

Record the maintenance work order, commissioning package, or test report reference.

Transformer type and configuration recorded

Record transformer type, voltage class, winding configuration, and whether the unit is energized or isolated.

Safety and Test Preconditions

Lockout-tagout applied and verified critical (required)

Confirm the transformer is isolated, de-energized, and controlled under lockout-tagout per OSHA 1910.147 before testing.

Yes No N/A

Absence of voltage verified critical (required)

Verify absence of voltage on all applicable terminals before connecting the megohmmeter.

Yes No N/A

Required PPE worn

Select all PPE used for the task, such as arc-rated clothing, voltage-rated gloves, safety glasses, and face shield as applicable.

Test area barricaded and controlled critical (required)

Confirm the test area is restricted to authorized personnel and warning signs are posted as needed.

Yes No N/A

Discharge procedure completed after test critical (required)

Confirm the transformer windings were discharged to ground after each test and before handling conductors.

Yes No N/A

Test instrument calibration current

Confirm the megohmmeter calibration or verification status is current and traceable.

Yes No N/A

Environmental and Test Conditions

Ambient temperature recorded

Record the ambient air temperature at the time of test.

Winding or oil temperature recorded

Record the transformer winding temperature or oil temperature used for temperature correction.

Relative humidity recorded

Record relative humidity because moisture can affect insulation resistance readings.

Surface condition and contamination noted

Document visible moisture, dirt, oil, or contamination on bushings, terminals, and test points.

Test voltage selected critical (required)

Record the DC test voltage applied by the megohmmeter.

Insulation Resistance Test Results

Winding-to-ground insulation resistance recorded critical (required)

Record the one-minute insulation resistance reading between each winding and ground.

Winding-to-winding insulation resistance recorded

Record the insulation resistance between applicable windings, if tested.

Ten-minute insulation resistance recorded critical (required)

Record the ten-minute reading used to calculate polarization index.

Polarization index calculated critical (required)

Record the polarization index as the ratio of ten-minute resistance to one-minute resistance.

Temperature-corrected insulation resistance recorded critical (required)

Record the insulation resistance corrected to the reference temperature used by the site procedure.

Acceptance, Deficiencies, and Closeout

Results meet site acceptance criteria critical (required)

Confirm the measured and temperature-corrected results meet the applicable site or OEM acceptance criteria.

Yes No N/A

Deficiencies or non-conformances documented

Describe any low readings, unstable readings, contamination, moisture ingress, or suspected insulation defects.

Corrective action recommended

Document recommended actions such as drying, cleaning, retesting, further diagnostics, or removal from service.

Photo evidence attached

Attach photos of the test setup, meter readings, nameplate, or any observed deficiencies.

Inspector signature

Signature of the person completing the inspection and test record.

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Run: Transformer Insulation Resistance (Megger) Test

Inspection Details

Safety and Test Preconditions

Environmental and Test Conditions

Insulation Resistance Test Results

Acceptance, Deficiencies, and Closeout

Get your results