Introduction

In three-phase Alternating Current (AC) systems, phase reversal and single phasing, i.e. phase loss, are the commonly observed fault conditions. Phase reversal fault generally arises from human errors during system installation or maintenance, and single phasing fault due to broken wire or mechanical failure, worn contact, blown fuse, and thermal overload. The consequences of these faults are unsafe conditions for systems operation, which can lead to severe damage and failures to the systems as well as injury to personnel. Hence, a phase-sequence and phase-loss monitoring unit is required for the three-phase AC systems. The monitoring unit detects the fault and notifies the system to take subsequent action to protect the load.

This application note describes the implementation of a phase sequence and phase loss detection system for a three-phase AC supply and demonstrates the detection of phase sequence and phase loss faults on emulated three-phase AC systems supply using the AVR128DA48 microcontroller. The demo is based on the AVR128DA48 Curiosity Nano development board, a Curiosity Nano Adapter board, and Mikroelektronika Click boards™. The supplemented firmware is developed with the AVR128DA48 microcontroller, using the Atmel START code configurator and Atmel Studio Integrated Development Environment (IDE). The firmware is also developed with the MPLAB® Code Configurator (MCC) and MPLAB® X Integrated Development Environment (IDE).

The AVR® DA is a feature-rich, high-performance, and low-power 8-bit microcontroller family. The built-in Zero-Cross Detector (ZCD), 12-bit differential Analog-to-Digital Converter (ADC), and timer/counter peripherals are essential in implementing a phase sequence detection application. The AVR DA microcontroller ZCD peripheral features interrupt generation on rising edge, falling edge, and both the edges. The combination of ZCD and the 12-bit differential ADC peripheral provides reliable, efficient, and cost-effective phase sequence detection solution over the conventional non-microcontroller based phase sequence detection solutions available for the multiphase AC supply.