Electromechanical overcurrent relays such as the IAC and CO are the historical backbone of power system protection. These relays use delicate mechanisms and precision components to develop their operating characteristics and are subject to misoperation and failure resulting from contamination, corrosion, and simple aging. As a result, frequent testing and recalibration are required to ensure proper operation. As the relays continue to age, failing internal insulation and increasing cost associated with maintenance and repair of the relays makes it increasingly difficult to ensure reliable operation. Reliable operation is essential for personal safety and the prevention of unnecessary outages and/or extensive damage due to overloads and faults.