Power distribution systems are the backbone of modern electrical infrastructure, responsible for transmitting electricity from generation sources to end-users. To ensure the smooth operation of these systems, protecting vital equipment from faults and overloads is crucial. One of the most important devices in this regard is the Power Distribution Relay. These relays are responsible for monitoring electrical parameters, detecting abnormal conditions, and activating protection mechanisms when necessary. In this article, we will explore the role, types, functions, and applications of Power Distribution Relays in modern electrical grids.