The transformer gas relay is a protective device installed on the top of oil-filled transformers. It detects the slow accumulation of gases, providing an alarm after a given amount of gas has been collected. Proper collection and analysis of these gas samples enables maintenance teams to accurately identify fault types and severity, forming the. Explore the key role of gas relays in power transformer protection. This in-depth guide explains its working principle, core functions, and why it is essential for preventing catastrophic failures in the era of smart grids and renewable energy. It is divided into light gas protection and heavy gas protection.