High Voltage Power Transformers are some of the most expensive equipment in electrical power networks (HVPT). In addition to the expense of repairs, disruptions in the delivery of electricity to customers are also a result of these equipment failures and malfunctions. Using preventive testing and online monitoring, the transformers may be scheduled for outages for upkeep and retirement. There are a variety of ways to monitor and identify transformer malfunctions in order to improve maintenance procedures. These devices have been in use for many years in various (electrical, mechanical, and environmental) circumstances. These are the most important elements, and they account for the majority of a company's total outlay of funds. In order for distribution transformers to last a long time, they must be used in their rated condition. Overloading, heating, low or high voltage/current, and other conditions that might cause a sudden failure or supply loss can severely shorten their lifespan. © 2022 Elsevier B.V., All rights reserved.