Transformer Logbook

A transformer logbook is a structured record-keeping document used to track the history, maintenance, inspection, testing, and operational data of a transformer. It ensures reliability, compliance with safety standards, and helps in fault analysis or future reference.

Sections of a Transformer Logbook

1. General Information

1. Transformer ID/Code: __________
2. Location: __________
3. Capacity (kVA/MVA): __________
4. Voltage Rating (Primary/Secondary): __________
5. Manufacturer: __________
6. Serial Number: __________
7. Year of Commissioning: __________
8. Cooling Type (ONAN/ONAF/OFWF, etc.): __________
9. Winding Configuration (Dyn11, Yd11, etc.): __________
10. Daily/Shift Operational Record

Date	Time	Load (kVA)	Voltage (kV)	Current (A)	Frequency (Hz)	Top Oil Temp (°C)	Winding Temp (°C)	Ambient Temp (°C)	Remarks

3. Maintenance Record

Date	Activity Performed	Parameters Checked	Results/Readings	Performed By	Remarks
05-08-2025	Oil level check	Oil sight glass	Normal	Technician A	OK
12-08-2025	Breather silica gel check	Gel color	Blue (OK)	Technician B	Needs replacement soon

4. Testing Record

Date	Test Type	Standard Used	Measured Value	Acceptable Value	Remarks
01-06-2025	Insulation Resistance (IR)	IEEE Std 43	1000 MΩ	> 500 MΩ	Pass
02-06-2025	Transformer Oil BDV	IEC 60156	65 kV	> 50 kV	Pass

5. Fault/Abnormality Record

Date	Type of Fault/Abnormality	Symptoms	Action Taken	Restored By	Remarks
10-07-2025	Overheating	High winding temperature	Load reduced	Technician A	Continuous monitoring required

6. Spare Parts & Consumables Record

Date	Item	Quantity	Issued By	Used For	Balance Stock

7. Inspection Checklist (Monthly/Quarterly/Yearly)

1. Oil level checked
2. Silica gel condition checked
3. Bushings clean and intact
4. Cooling fans/pumps operational
5. Protection relays tested
6. Earth connections tight
7. DGA (Dissolved Gas Analysis) carried out
8. Tap changer inspected

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Importance of Transformer Logbook

• Helps in preventive maintenance.
• Provides history for fault investigation.
• Ensures compliance with safety standards.
• Extends equipment life.
• Useful during audits and inspections.