Transformer Pre-Energization Checklist

Pre-energization inspection for power transformers before first charge, covering oil level, insulation resistance, turns ratio, grounding, tap position, bushings, protection settings, and readiness for safe energization.

Inspection Details and Safety Controls

• Transformer identification matches the approved commissioning record
  Verify nameplate data, serial number, kVA/MVA rating, voltage class, and location match the energization package.
• Lockout-tagout and switching order are in place
  Confirm the transformer and associated circuits are controlled under an approved lockout-tagout procedure per OSHA 1910.147.
• Required PPE is selected for the task
  Select the PPE required by the energized work boundary and hazard assessment per NFPA 70E.
• Work area is barricaded and access is controlled
  Verify the area is clear of unauthorized personnel and barriers/signage are installed as required.
• Inspection package and approved drawings are available
  Confirm the latest one-line, settings sheet, test results, and energization authorization are available to the inspector.

Transformer Condition and Oil System

• Oil level is within the acceptable operating range
  Verify the oil level indicator is within the manufacturer-specified normal range and no low-oil alarm condition is present.
• No visible oil leaks, seepage, or active drips
  Inspect the tank, valves, gaskets, radiators, conservator, and fittings for leakage.
• Pressure relief device, breather, and conservator components are intact
  Confirm visible condition of pressure relief, silica gel breather, and conservator piping where applicable.
• Tank, radiators, and fittings are free of physical damage
  Check for dents, corrosion, loose hardware, missing covers, or other non-conformances that could affect safe operation.
• Oil sampling, test, and filtration records are complete
  Confirm required oil quality checks, moisture results, and any filtration or degassing actions were completed and accepted.

Bushings, Terminations, and Grounding

• Bushings are clean, intact, and free of cracks or chips
  Inspect all high- and low-voltage bushings for contamination, damage, tracking, or oil leakage.
• Bushing connections and hardware are tight and properly torqued
  Verify terminations, jumpers, and hardware are secure and installed per approved torque specifications.
• Grounding connections are installed and continuous
  Confirm tank ground, neutral ground, and any equipment grounding conductors are present, secure, and bonded.
• Ground resistance or continuity test result is acceptable
  Record the measured grounding continuity or resistance value used by the commissioning procedure.
• Surge arresters and neutral links are correctly installed
  Verify arrester connections, neutral links, and any removable bonds are installed per design.

Electrical Tests and Tap Configuration

• Insulation resistance (IR) test completed and acceptable
  Enter the measured insulation resistance value and confirm it meets the project or manufacturer acceptance criteria.
• Turns ratio test (TTR) results are within tolerance on all required tap positions
  Verify the TTR test was completed and all measured ratios are within the acceptable tolerance for each required tap position.
• Tap changer position matches the approved energization setting
  Confirm the off-circuit or on-load tap changer is set to the documented pre-energization position.
• Winding polarity, phase rotation, and vector group are verified
  Confirm test results match the design data and system interconnection requirements.

Protection, Controls, and Final Readiness

• Protection relays and settings match the approved coordination study
  Verify relay settings, CT/PT ratios, and trip logic correspond to the approved setting sheet.
• Alarm and trip circuits are functional
  Confirm any required alarm, trip, and indication circuits have been checked and are operational.
• All covers, barriers, and access panels are secured
  Verify all removable covers, doors, and access points are closed and secured prior to energization.
• Transformer is approved for energization by the responsible authority
  Final authorization is confirmed by the commissioning lead, competent person, or AHJ as applicable.

Inspector Findings and Sign-Off

• Deficiencies or non-conformances noted
  List any deficiencies, observations, or exceptions identified during the inspection.
• Corrective actions completed or assigned
  Document corrective actions, responsible party, and target completion date if applicable.
• Inspector signature
  Signature of the inspector completing the pre-energization checklist.