Computer generation of test quantities for testing protection relays

Modern high-voltage power systems need secure high performance protection devices which have a high speed of operation for internal system fault conditions and a high level of discrimination between internal and external system faults. To achieve the high performance required by the power system, modern protection devices have, of necessity, become complex, electronic measuring systems employing large numbers of diverse types of electronic components. This increase in complexity along with the need to reduce the cost of maintenance has encouraged the development and use of automated protection test equipment. The author briefly describes an automatic protection test set which has been in use for a number of years in the UK, and describes how it has been further developed both to keep pace with developments in relaying and to satisfy users requirements for more flexible and cost effective equipment