What is the most common relay used for Line protection?

The most common relay used for line protection is the overcurrent relay. This relay is designed to detect excessive current flow in a circuit and operate to disconnect the line to prevent damage to equipment and ensure safety. Overcurrent relays are widely utilized because they effectively protect against both short-circuits and overload conditions. They can be set to operate at specific current levels and provide prompt response to fault conditions, making them essential in protective schemes for electrical systems.

In contrast, while distance relays are important in certain applications like transmission line protection, they are more specialized and not as commonly used for all types of line protection as overcurrent relays. Frequency relays monitor changes in frequency but are not generally used specifically for line protection. Resistance relays are less common and mainly utilized for specific applications rather than for general line protection. Therefore, the overcurrent relay stands out as the most prevalent choice due to its versatility and effectiveness in a variety of line protection scenarios.