The paper should provide a historical overview of relay protection with a special emphasis on current numerical relays. Also, the ABB numerical relay, type REF615, should be described in detail. Furthermore, the candidate should state the characteristics of the Omicron CMC-256/6 relay testing instrument as well as the PGX30 relay testing measuring system from CMC Protection. Using the mentioned systems, measurements should be carried out on a specific example to verify the correctness of the relay, compare the measurement results obtained with different instruments and create appropriate test protocols.