This book was created for relay test technicians and provides the knowledge and skills necessary to test most of the modern protective relays installed over a wide variety of industries. Basic electrical fundamentals, detailed descriptions of protective elements, and generic test plans are combined with examples from real life applications to increase your confidence in any relay testing situation. A wide variety of relay manufacturers and models are used in the examples to help you realize that once you conquer the sometimes confusing and frustrating man-machine interfaces created by the different manufacturers, all digital relays use the same basic fundamentals and most relays can be tested by applying these fundamentals.By the end of this book, you will have the information you need to: Evaluate relay applications Review, understand, and compare the relay settings to the application Create a test plan Test the most commonly applied elements:Instantaneous Overcurrent (50)Inverse Time Overcurrent (50)Directional Overcurrent (67)Undervoltage (27)Overvoltage (59)Over/Under Frequency (81)Differential (87) (With three of six current channels)Line Distance (21) Evaluate the test results Provide comprehensive test results and documentationEach chapter is a self contained unit and the chapters are organized in a logical progression of knowledge to allow readers from different skill sets to focus on or skip to the sections they need without wasting time reading through information they already know. We also provide packages for technicians who are looking for specific information only. These packages can be downloaded in pdf format for easy viewing and printing as they become available.