A Comprehensive Review of Recent Developments in Thermal Condition Monitoring of Dry-type Transformers

At present, oil-filled transformers are experiencing installation problems under tough environmental conditions, oil spilling during operation, pollution from the oil spillage, preventive maintenance issues and shorter maintenance schedules. The fire accidents triggered by the insulating oil can lead to economic issues. To overcome oil-filled transformers' technical and economic issues, researchers suggest installing dry-type transformers. The dry-type transformer requires fewer maintenance strategies, but for better operation, some condition monitoring techniques are followed. This paper proposed a review of some important research work on the thermal condition monitoring techniques of dry-type transformers. The thermal profile of the transformer is a key indicator of any losses and faults. This study initially eyes the temperature rise factors and operating conditions. The temperature distribution factors like conduction, convection and radiation are discussed to identify the thermal distribution in the transformer. This study encourages suitable thermal monitoring and diagnostic techniques to supervise the thermal profile at different loading and operating conditions. The analysis of the hotspot is an integral part of this thermal condition monitoring study. The hotspot localization from the thermal monitoring dataset and relevant analysis strategies are considered in the research work. The thermal analysis of the dry-type transformer includes multiple online and real-time approaches in the recent literature are discussed briefly. The advantages, limitations and challenges furnish a broad perspective on the suitable thermal monitoring techniques and appropriate analysis methods. The research results of the review article can provide innovative ideas for future research developments in this field.