Microprocessor-based testing of protection relays

To ensure the integrity of electrical transmission and distribution networks it is vital that protection relays are tested on a regular basis. Developments in the automation of relay test sets utilising the latest microprocessor technology now permit more frequent and accurate testing. The application of these new developments to the monitoring of transmission and distribution relays is discussed by particular reference to two models of an automated relay test set, one for complex three phase schemes; the other for routine single phase protection