Overhauling and maintenance of power and distribution transformers are essential activities to ensure the reliability and longevity of these critical components in the electrical power infrastructure. Regular maintenance and, when required, overhauling help prevent unexpected failures, improve efficiency, and extend the lifespan of transformers. Here's a general overview of the maintenance and overhauling process:

Regular Maintenance:

1. Visual Inspection:

   • Regularly inspect the external condition of the transformer for signs of leaks, corrosion, or physical damage.
   • Check the transformer's foundation and support structures for stability.

2. Oil Analysis:

   • Collect oil samples regularly to perform dissolved gas analysis (DGA) and other tests.
   • Monitor oil quality, including acidity, moisture content, and contamination.

3. Electrical Tests:

   • Conduct routine electrical tests such as insulation resistance, turns ratio, and power factor tests.
   • Check for any abnormalities in the transformer's electrical parameters.

4. Cooling System Inspection:

   • Inspect the cooling system components, such as radiators or fans, for cleanliness and proper operation.
   • Clean or replace air filters as needed.

5. Bushings and Insulators:

   • Inspect bushings and insulators for cracks, leaks, or other signs of degradation.
   • Check for proper electrical connections.

Overhauling:

1. Dismantling:

   • Disconnect and de-energize the transformer.
   • Drain the oil and disconnect electrical connections.
   • Dismantle the transformer, separating its core and windings.

2. Core Inspection:

   • Inspect the transformer core for any signs of damage, such as hot spots or core laminations.
   • Clean the core and check for proper insulation.

3. Winding Inspection:

   • Examine the windings for signs of overheating, insulation breakdown, or mechanical damage.
   • Re-varnish or re-insulate windings if necessary.

4. Tap Changer Maintenance:

   • Inspect and clean the tap changer mechanism.
   • Lubricate moving parts and replace any worn-out components.

5. Oil Treatment:

   • Purify the transformer oil to remove contaminants.
   • Test and treat the oil for proper dielectric strength.