Directional overcurrent relay is used for the protection of:

A directional overcurrent relay is used for the protection of ring main distribution lines. When there exists a sub-transmission network or a complex distribution, the relays are used to improve the coordination of the system. It is thus proved that one can use a directional overcurrent relay for the protection of the ring main distribution lines. Directional overcurrent relays are a type of relay that often respond to excessive current flow in a particular direction of the power system. Generally, there are two elements in a relay. One of the two-element is the element of the direction. In a directional element of a relay the direction of current flow with respect to a voltage reference. A normal non-directional overcurrent is used on incoming line circuit breakers that have two or more sources.