High voltage (HV) systems are integral to the distribution of electrical power over long distances, supplying electricity to industries, homes, and other essential infrastructure. Ensuring the reliability and safety of these systems is paramount, and one of the key components designed to protect these systems is the HV insulation fault relay. This device plays a critical role in detecting insulation faults in high voltage circuits, thus preventing catastrophic failures and ensuring uninterrupted power delivery. In this article, we will explore the importance, functionality, and operation of the HV insulation fault relay, as well as its role in maintaining the safety and integrity of electrical networks.