DESIGN AND CONSTRUCTION OF THE MULTI MICROCONTROLLER BASED NUMERICAL UNDERVOTAGE PROTECTION RELAY

Abstract

This paper presents a design and construction of the multimicrocontroller based numerical undervoltage protection relays, applied in industry and household electrical appliances. In addition, the relay also serves the teaching of electrical engineering and automation majors in engineering schools thanks to its ability to connect to a PC to change the relay's parameters via software. The hardware of the relay is designed using two Atmega16 microcontrollers, which is a popular microcontroller on the market. To improve the accuracy of the relay, the software for the relay is designed based on the interrupts of the microcontroller, which uses the external interrupts to change the value of the setting voltage and delay time of the relay, the ADC interrupt to read the protected grid votage. In addition, another important solution that contributes to improve the accuracy of the relay used in this paper is the linearization method for each segment to overcome the nonlinear nature of the potential transformer. Experiments for the designed and built  numerical undervoltage protection relay was conducted to evaluate and confirm the quality of the relay.