A proposed procedure for monitoring, overhauling, and maintaining on-load tap changers (OLTCs) in 110 kV transformers

Transformers constitute a critical component of national power transmission and distribution systems, particularly at voltage levels of 500 kV, 220 kV, and 110 kV, with the on-load tap changer (OLTC) serving as an indispensable element in ensuring operational stability. This study draws on periodic oil testing conducted by the Southern Power Testing Company’s Petrochemical Testing Laboratory and other service providers, encompassing multiple transformer components. Based on the analysis of these diagnostic data, the study develops and presents a systematic procedure for monitoring and overhauling OLTCs in 110 kV transformer systems in the Southern region. The proposed framework supports the assessment of equipment condition, lifespan, and operational reliability, thereby contributing to the stable and efficient operation of transformers across the 110 kV grid under the Southern Power Corporation.