1️⃣ Transformer Maintenance Checklist

A. Daily Checks

✔ Check for unusual noises (humming, buzzing, or crackling sounds).
✔ Inspect for oil or coolant leaks.
✔ Monitor transformer temperature (oil & winding).
✔ Check load current and voltage levels for abnormalities.

B. Monthly Checks

✔ Inspect bushings for cracks or dirt buildup.
✔ Check silica gel in the breather (should be blue, not pink).
✔ Ensure cooling system (fans/pumps) is operational.
✔ Verify grounding connections are secure.
✔ Inspect for rust or corrosion on the body and bolts.

C. Quarterly Checks

✔ Perform Dissolved Gas Analysis (DGA) on transformer oil.
✔ Test insulation resistance using a Megger tester.
✔ Inspect cooling system for dirt, blockages, or fan malfunctions.
✔ Test protective relays and alarms (temperature, Buchholz relay, pressure relief).

D. Annual Checks

✔ Perform oil filtration if needed (based on DGA & moisture analysis).
✔ Conduct Transformer Turns Ratio (TTR) testing.
✔ Check tightness of all electrical connections using a torque wrench.
✔ Inspect tap changer contacts for wear and clean if needed.
✔ Conduct thermographic (infrared) scanning to detect hotspots.
✔ Perform a sweep frequency response analysis (SFRA) for internal winding movement.

E. 5-Year Overhaul

✔ Complete oil change if necessary.
✔ Test and replace worn-out gaskets and seals.
✔ Repaint the transformer to prevent corrosion.
✔ Conduct a thorough core and winding inspection.

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2️⃣ Transformer Maintenance Schedule

Activity	Daily	Monthly	Quarterly	Annually	5 Years
Visual inspection	✅	✅	✅	✅	✅
Check for leaks	✅	✅	✅	✅	✅
Oil level check	✅	✅	✅	✅	✅
Bushing inspection		✅	✅	✅	✅
Cooling system check		✅	✅	✅	✅
Dissolved Gas Analysis (DGA)			✅	✅	✅
Insulation resistance test			✅	✅	✅
Thermographic scan			✅	✅	✅
Oil filtration				✅	✅
Tap changer maintenance			✅	✅	✅
Core & winding inspection					✅

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3️⃣ Transformer Troubleshooting Guide

Here’s a quick guide to diagnosing and fixing common transformer issues:

A. Transformer Overheating

❌ Possible Causes:

• Overloading
• Cooling system failure (fans/pumps not working)
• Blocked radiators or dirty cooling fins
• Insulation deterioration

✅ Solution:

• Reduce the load if overloaded.
• Check and clean the cooling system.
• Conduct insulation resistance tests and replace damaged parts.

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B. Low Oil Level / Oil Leaks

❌ Possible Causes:

• Leaking gaskets or seals
• Loose fittings or corroded welds
• Excessive internal pressure

✅ Solution:

• Identify and repair leaks.
• Replace gaskets or seals.
• Perform oil analysis and refill with proper grade oil.

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C. High Gas Levels in DGA Test

❌ Possible Causes:

• Hydrogen (H₂) → Partial discharge (incipient fault).
• Methane (CH₄) & Ethylene (C₂H₄) → Overheating.
• Acetylene (C₂H₂) → Arcing inside transformer.

✅ Solution:

• Conduct infrared scanning to detect overheating.
• Inspect internal parts for tracking or partial discharge.
• If acetylene is present, immediately shut down and investigate.

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D. No Output Voltage / Low Voltage

❌ Possible Causes:

• Tap changer in the wrong position
• Winding damage or open circuit
• Loose or corroded connections

✅ Solution:

• Check tap changer settings.
• Perform a winding resistance test.
• Inspect and tighten connections.

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E. Excessive Noise (Humming or Buzzing)

❌ Possible Causes:

• Loose core bolts
• Overloading
• Magnetic flux leakage

✅ Solution:

• Tighten core bolts and laminations.
• Reduce load if needed.
• Check insulation and core grounding.