Aspects regarding the Protection Relays from Power Substations

The first smart electronic devices with microprocessor technology were introduced in the early 1980s. Microprocessor-based relays are often called numerical relays, because analog inputs are converted into numbers that are processed by the relay. At present, there is a tendency to replace the classical devices in the protection, measurement, signaling and control systems with digital relays that achieve better performance. Among the advantages of the new digital relays we can enumerate that they can incorporate more functions into one device. The paper will describe some aspects about the relays which are found in the power substation and for the case study was tested an electronic, electromagnetic and numerical relay. Also, was performed a comparative analyses from the obtained results.