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Run: Transformer Turns Ratio (TTR) Test Inspection

Record transformer turns ratio measurements at every tap position and compare them to the design ratio. Use this template to catch winding, polarity, and tap...

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Test Setup and Equipment Identification

Transformer identification matches work order and nameplate critical (required)

Verify transformer serial number, asset ID, voltage class, and phase designation against the work order and nameplate.

Yes No N/A

Test instrument calibrated and suitable for TTR measurement critical (required)

Confirm the TTR test set is within calibration and appropriate for the transformer voltage class and winding configuration.

Yes No N/A

Photo evidence (optional)

Transformer isolated and de-energized under lockout-tagout critical (required)

Confirm the transformer is de-energized, grounded as required, and controlled under lockout-tagout before testing.

Yes No N/A

Ambient conditions and test notes recorded

Record ambient temperature, humidity if required by procedure, and any conditions that could affect test interpretation.

Applicable test procedure or SOP referenced

Enter the procedure, standard work instruction, or commissioning checklist used for this inspection.

Design Ratio and Tap Configuration

Design turns ratio documented for each winding pair critical (required)

Record the expected design ratio for each applicable winding pair before testing.

Tap changer type and range confirmed critical (required)

Identify whether the transformer uses de-energized tap changing or on-load tap changing and record the available tap range.

All tap positions identified for test sequence critical (required)

Confirm the full tap sequence to be tested, including neutral and all raise/lower positions as applicable.

Note (optional)

Expected tolerance for turns ratio deviation recorded critical (required)

Enter the allowable deviation from design ratio per manufacturer specification or site acceptance criteria.

Note (optional)

Turns Ratio Measurements by Tap Position

Measured turns ratio at neutral tap critical (required)

Record the measured ratio at the neutral tap and compare it to the design ratio.

Note (optional)

Measured turns ratio at each raise tap critical (required)

Record the measured ratio for each raise tap position tested and note any deviation from the design ratio.

Measured turns ratio at each lower tap critical (required)

Record the measured ratio for each lower tap position tested and note any deviation from the design ratio.

Percent deviation calculated for all tested taps critical (required)

Document the percent deviation between measured and design ratio for each tap position.

All measured values within allowable tolerance critical (required)

Confirm that every tested tap position is within the specified tolerance band.

Yes No N/A

Winding and Tap Changer Integrity

No indication of open winding, shorted turns, or incorrect polarity critical (required)

Assess test results for signs of winding defects, incorrect connections, or polarity issues.

Yes No N/A

Tap changer operation consistent across all positions critical (required)

Verify the tap changer moved and indexed correctly through the full range without binding, misalignment, or abnormal behavior.

Yes No N/A

Abnormal noise, overheating, or mechanical damage observed critical (required)

Record any abnormal condition observed during setup, tap changes, or measurement.

Yes No N/A

Deficiencies or non-conformances documented

List any deficiencies, non-conformances, or follow-up actions required before energization.

Results, Corrective Action, and Sign-off

Inspection result critical (required)

Select the overall outcome of the TTR inspection.

Corrective action and retest plan

Describe any corrective action, retest requirement, or escalation to engineering or the AHJ if applicable.

Inspector signature critical (required)

Inspector sign-off confirming the recorded measurements and findings are accurate.

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