Design and implementation of protective relay testing device using microcontroller and servo-motor

One of the major elements in power system protection is a protective relay. Prior to its installation and continuous use in the system, the relay needs to be tested accurately. Many capable devices are available in the market for this purpose which are costly. In this paper, a cost-efficient relay testing device is designed and implemented using microcontroller and servo-motor. The device is capable of accurately testing a protective relay in system frequency for under-voltage and overvoltage conditions with a maximum error of 2%.