DESIGN AND DEVELOPMENT OF MICROPROCESSOR BASED MULTI FUNCTIONAL RELAY

Abstract

The author in this report presents the design and development of processor based multifunctional relay. The functions implemented are over current relay, Earth fault relay, Under/Over voltage relay, Under/Over frequency relay. The user can select different combination of relays, the options are as follows Over current and earth fault relay Over/Under voltage relay. Over current and Over/Under voltage. Over current, Earth fault and Over/Under voltage. Under/Over frequency relay All the functions of the relay. ( i.e. over current, Earth fault relay, Under/Over voltage relay, Under/Over frequency) Characteristics provided for over current and earth fault are Very Inverse. Extremely Inverse, Definite time and Inverse definite minimum time. Characteristics provided for Over/Under voltage and Over/Under frequency relay are. Inverse definite minimum time and definite time. Programming for implementing all the relays is done on a MATLAB platform and an Executable file (.exe) is generated which is a standalone windows application. The multifunctional relay is tested practically for different standard settings and compared with standard characteristics and the results are tabulated. The effect of noise transients and harmonics is also considered in the design and development of multifunctional relay. The effect of harmonics on the relay is studied by using Electrical Power Standard Fluke make. The equipment provided variable frequency and harmonics with respect to fundamental frequency of 50 Hz