Transformer Overhauling is a comprehensive maintenance procedure that restores a transformer to its optimal operating condition. It is a more extensive service than a simple repair, often performed on older units or after an internal fault. The process typically involves dismantling the transformer, followed by a thorough inspection of the core and windings. Key components like gaskets, bushings, and tap changers are inspected and replaced as needed. The insulating oil is often drained, and the tank is cleaned to remove sludge and impurities. After reassembly, the transformer is refilled with fresh oil and undergoes a series of rigorous electrical tests to confirm it is fully functional and safe to operate.