3 Application Overview

This application showcases phase sequence detection, phase-loss detection and RMS voltage measurement on an emulated three-phase A/C supply, using the PIC18F56Q24 microcontroller.

Three MikroElektronika Waveform Clicks are used in the application to emulate a three-phase signal. The Waveform Click board generates sinusoidal signal with desired amplitude, phase and frequency. The application uses the Waveform Clicks to generate three 3.3V sinusoidal signals with 50/60 Hz and 120° phase difference to serve as the A/C supply. Additionally, to showcase the various faults, the Waveform Clicks can be reconfigured by the application in run time to change the output signal.

In this application, the Data Visualizer tool is used to interact with the application firmware through an Universal Asynchronous Receiver Transmitter (UART) interface. The Data Visualizer is used to monitor and report the live status of phase reversal and phase loss. It is also used to send the emulator commands to replicate the various faults using the Waveform Clicks.

Figure 3-1 illustrates the block diagram of the phase sequence detection application note.

To select between the 50 Hz and the 60 Hz operating mode, the on-board Curiosity Nano switch is used. The system stays in Frequency Selection mode for 10 seconds after power-up. By default, the system starts with 50 Hz frequency and it can be changed by pressing the switch after the board is powered up. The selection change can be viewed on the dashboard window of the Data Visualizer.

The application continuously monitors the three-phase power supply for phase reversal and phase-loss faults. The results of phase sequence and phase loss of the three-phase signal are continuously updated on the dashboard window.

Upon receiving the user inputs to demonstrate phase-loss and phase-reversal faults from the dashboard, the application updates the configurations of Waveform Clicks. Thereby, the three-phase signal with desired fault condition is generated by the Waveform Clicks.

Also, the application restores the fault conditions when an appropriate command is received from the dashboard to recover from the fault condition.