Technical loss reduction through active repair of distribution transformers: Results from the field

Distribution Transformers (DTs) are key assets for any distribution network. Their reliable and efficient operations is important for strong economic standing of the DISCOMs. Many DISCOMs follow DT energy audit, but that focuses on AT&C losses external to the DT. This paper focuses on Technical losses internal to the DTs and how best it can be reduced. DT technical losses usually gets measured only at the repair facility during the breakdown event. In old legacy DTs, these technical losses stand highly deviated from original manufacturing specs, adding to the financial losses of the DISCOMs. This paper presents a technical loss reduction technique called `active repair' using winding compensation only, with no change to the core. Active repair was conducted on two Aluminum wound legacy DTs with high technical losses, one failed DT of 100 kVA and other functional DT of 200 kVA, with winding compensation carried out through copper winding replacement. Results demonstrated significant technical loss reduction to near manufacturing specs, with business viability to the DISCOMs. Active repair can be further developed as an easy replicable DT repair technique, and DISCOMs can selectively apply it to high technical losses legacy DTs that will yield shorter payback period. Existing DT repairers can be incentivized to undertake active repairs through performance tied improved service level agreements (SLAs) with further extension to provide integrated DT managed services for improved reliability and life cycle management.