A review on transformer condition monitoring with critical investigation of mineral oil and alternate dielectric fluids

Transformers are very critical elements of modern power system network and have evolved in many ways over its long history. Transformers are most significant apparatus in interconnected power systems with consideration of several aspects like reliability, efficiency, economy, wide applications and operation. However mineral oil also called transformer oil is attracting more attention from researchers and transformer industry due to environ-mental concerns, limited stock, high price of petroleum resources and its disposal issues after getting contami-nated. Above issues have motivated researchers to turn their attention to biodegradable and/or renewable insulating oil. Multiple facets, such as environmental requirements, safety and economic considerations, avail-ability of technology and raw material governs the development of new insulating liquid materials. In addition, the increased equipment efficacy and the adoption of more environment friendly alternate dielectric fluids for power system solutions is gaining popularity towards steps to reduce the carbon footprint and achieving net zero cum decarbonisation global policy. This article provides the detailed review of transformer condition monitoring and the critical investigation about environment friendly dielectric fluids. They claim excellent lifecycle of the insulation, better working compatibility and improved performance compared to the traditional mineral oil base fluids in adherence of compliance, standards and graphical abstracts. These alternate dielectric fluids are getting proved as superior transformer fluids. The diverse investigational work carried out is incorporated, providing an overview of research. In addition, the future scopes, challenges and environment friendliness of various fluids are studied and deliberately articulated.