Transformer Checklist

1. General Information

1. Transformer ID/Code: __________
2. Location: __________
3. Rating (kVA/MVA): __________
4. Voltage Ratio (HV/LV): __________
5. Type: Oil-immersed / Dry type
6. Cooling: ONAN / ONAF / OFWF, etc.
7. Serial Number: __________
8. Year of Commissioning: __________
9. Inspector Name: __________
10. Date: __________

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2. Daily / Shift Checklist

1. Oil level normal (sight glass)
2. Oil & winding temperature normal
3. Buchholz relay alarm/trip free
4. No leakage of oil observed
5. Silica gel (breather) condition normal (blue/pink)
6. Cooling fans/pumps working
7. Pressure relief device normal
8. No abnormal sound/vibration
9. HV & LV bushings clean and intact
10. Panel indicators/alarms working

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3. Weekly Checklist

1. Check earthing connections tight
2. Inspect conservator tank oil level
3. Breather silica gel condition checked
4. Cooling system auto/manual operation test
5. Thermometer calibration verified
6. Ensure no dust or moisture inside panel

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4. Monthly Checklist

1. Check oil leakage at joints/gaskets
2. Inspect physical condition of bushings (cracks, flash marks)
3. Clean bushings and terminals
4. Test fans and oil pumps
5. Check relay indication and reset
6. IR (Insulation Resistance) test of control circuits

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5. Quarterly / Half-Yearly Checklist

1. Dissolved Gas Analysis (DGA) of oil
2. Transformer oil BDV (Breakdown Voltage) test
3. Insulation resistance test of windings
4. Functional test of Buchholz, PRV, WTI, OTI relays
5. Tap changer inspection (oil level, mechanism, contacts)
6. Measure earth resistance of transformer body & neutral

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6. Yearly Checklist

1. Complete oil filtration/treatment (if required)
2. Calibration of protection relays (REF, differential, overcurrent, Buchholz, etc.)
3. Transformer ratio test (TTR)
4. Winding resistance test
5. Contact resistance measurement (if OLTC present)
6. Capacitance & Tan-Delta test of bushings
7. Thermography of connections, bushings & terminations
8. HiPot test (as per OEM guidelines)

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7. Safety Checks

1. Danger signage installed and visible
2. Fire extinguisher available near transformer
3. Oil soak pit/fire protection system in place
4. LOTO (Lock-Out/Tag-Out) used before maintenance
5. PPE worn during inspection/maintenance

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✅ Importance of Transformer Checklist

1. Prevents failures & unplanned shutdowns
2. Ensures long transformer life & efficiency
3. Helps in predictive maintenance
4. Provides history for audits & compliance