Microprocessor-Based Transmission Line Relay Applications

For many years, utilities have used electromechanical relays for power system protection. The result of using electromechanical relays has been an extensive maintenance and design practice. Both the maintenance and design of protection schemes using these relays is expensive and time-consuming. Over the last ten years, microprocessor-based relays have come of age. Microprocessor-based relays offer many advantages over electromechanical relays. This paper compares a typical transmission line protection scheme in terms of cost, engineering design, and maintenance. The information presented in this paper shows that microprocessor-based relays offer significant savings in cost, engineering design, and maintenance. The paper concludes by showing many transmission line protection applications for microprocessorbased relays