Giving new life to the legacy Distribution Transformers through Proactive repair

Abstract— Distribution Transformer (DT) is the heart of distribution network. It is essential to monitor its health as it is one of the high CAPEX assets for DISCOMs. For overall DISCOM viability, it is important that each individual DT is turned into a profit center. It is estimated that of 24% national average AT&C losses, at least 3- 4% comes from Technical losses in DTs alone, and it can be brought down to 0.5% and below. Restructured Accelerated Power Development and Reforms Programme (R-APDRP) has envisaged utilities to carry out an energy audit of a DT for monitoring losses (at least on a sampling basis) but unfortunately, this keeps missing the attention, add to the extent that DT technical losses are not even measured till it breaks down. And only broken- down DTs are sent for repair, and there is minimum to none pro-active approach to DT renovation, repair towards modernisation and O&M.

This article presents a repair concept called ‘Proactive Repair’ using winding compensation only, with no change to the healthy core. Proactive repair was conducted in field at Madhya Pradesh Paschim Kshetra Vidyut Vitaran Company Limited (MPPKVVCL), Indore on Aluminum wound legacy DTs (100kVA and 200kVA) with high technical losses, with winding compensation carried out through copper winding replacement. Results revealed significant technical loss reduction, reliability improvement and kVA enhancement of the repaired DTs thereby breathing new life in them.

The proposed proactive repair can be developed as an easy replicable DT repair technique, and DISCOMs can selectively apply it to high technical loss-making legacy DTs that will yield shorter payback period. Existing DT repairers can be incentivized to undertake proactive repairs through performance tied improved repair contract or service level agreements (SLAs) with further extension to provide integrated DT managed services for improved reliability and life cycle management.