## 4 Results and Discussion
### Transformer Condition Monitoring
#### 4.8.4 Partial Discharges
Together, these findings demonstrate the breadth of research conducted on the use of the Internet of Things to enhance the efficiency, dependability, and performance of electrical transformers. The relatively small amount of research articles in areas such as vibration analysis, energy consumption optimization, and partial discharge analysis in the context of IoT technology for electrical transformer condition monitoring points to a few noteworthy conclusions. In the first place, it highlights a stark research gap in these areas, demonstrating that insufficient attention has been paid to them in the context of Internet of Things transformer applications. Secondly, it is possible that the complexity and unique challenges associated with these subjects have discouraged more research. Additionally, these fields may be considered niche or specialist, meaning that fewer scholars are working on them than on subjects like fault diagnosis or lifecycle management, which are subjects that are studied more extensively. Lastly, it is important to remember that research in these domains may still be in its early stages. However, if IoT technology for transformer monitoring develops further, we may anticipate seeing an increase in the amount of research produced in these areas. The dearth of research publications in these areas ought to be seen as a request for increased investigation and innovation inside the sector. Figure 10 clearly demonstrates that the majority of the references conducted studies on fault diagnosis using IoT technology. Only [21; 81] investigated the impact of vibrations in the transformer. When a fault condition arises within the transformer, the vibrations from the windings due to fault currents are a clear indication of the abnormal condition arising within the transformer. This area needs to be explored more. Figure 8 additionally illustrates that 55 publications conducted an investigation on transformer fault diagnosis using the Internet of Things. This aspect is crucial in ensuring longer service life of  
Figure 10: Research distribution by the transformer aspect investigated. transformers. A total of 29 publications conducted investigations on health indices to calculate transformer health indices and estimate the remaining life of transformers. A total of 27 reviewed papers focused on the lifecycle management of transformers. This is an asset management technique usually consisting of three steps; firstly, it involves risk evaluation for transformer assets. Secondly, it assesses the condition of each transformer, and, thirdly, involves alternative actions in the lifecycle, such as retiring, refurbishing, replacing, and discarding transformers [52]. Energy management aspects were the focus of five reviewed papers, utilizing IoT technology to monitor energy consumption and power theft. References [88; 116] did not specify the aspects they investigated in their publications. References [21; 81] were the only two papers looking into the vibration analysis of transformers using IoT technology. RQ2: Which research publication sources have been predominantly utilized in the literature to study IoT applications in transformer monitoring? The analysis of the published sources in Figure 11 shows how widely the literature on IoT technology for electrical transformer status monitoring is distributed. Conferences make up the bulk of the landscape with 55% publications, while journal articles only account for 45% publications. This distribution suggests that conference proceedings are the preferred means of disseminating research findings among the academic community researching this subject. Conference publications are very common for a variety of reasons. First of all, conferences are a well-liked substitute for disseminating cutting-edge studies in fields that are always evolving, such as IoT technology, since they usually provide a forum for scholars to promptly share their most recent findings and discoveries.