User`s guide

11
5 - Implementation of a digital relaying algorithm
5.1 – Relays of the past and present
Since the beginning of the 20
th
century, relays built with electromechanical components have
been used. Reliability and robustness are characteristics for these power electronic artifacts,
and have contributed to their long reign of success.
In the 1960’s, the first investigations into computer relaying was made. The idea at the time
was to integrate all relay applications in one substation into a single computer. This was
necessary due to the expensive nature of computers at the time. Still, the cost, power
consumption and comparatively slow computation speed of the computers couldn’t compete
with conventional relays.
Over the following decade, major advances in computer hardware were made – along with
faster and more efficient algorithms – computer relays performing just as good as their
conventional counterparts were presented in the early 1970’s. During the 1980’s the speed of
processors rose as quick as the manufacturing cost plummeted, which led to the slow
replacement of electromechanical relays by their superior digital brethren. This is a trend that
continues to this day.