Deployment of InAlN/GaN Hall-effect Sensors for Bucket Transformer Monitoring and Forecasting

Every transformer has a core that produces a powerful AC magnetic field while in operation, which can be measured to monitor the health and performance of the transformer in real time. However, the environment inside of a bucket transformer presents several challenges for sensor survival, including magnetic fields with leakage fluxes on the order of 300 mT, the possibility of shorts that can generate fields as high as 2.5 T, a wide range of temperatures from -40 to 140°C, and full submersion in hot mineral oil for extended periods (as long as decades). In an effort to produce magnetic field sensors that can survive within harsh transformer environments, we examined established InAlN/GaN wide bandgap Hall-effect sensors in collaboration with Prolec GE. The sensors proved capable of withstanding numerous environmental conditions inside a transformer. In addition, by integrating InAlN/GaN Hall-effect sensors with an analog-to-digital converter (ADC) and a microcontroller, real-time AC magnetic field signals were measured and stored at a sampling rate of ~1 kHz. This work demonstrates the ability to utilize embedded magnetic field sensor systems to monitor, diagnose, and forecast electric grid system health and performance via Internet-of-Thing (IoT) platforms.