Power·Jan 1, 2024

Automatic Power Factor Corrector and Monitor Device

Automatic capacitor-bank controller that monitors AC load behavior and improves power factor in real time.

Overview

This system monitors an AC load, estimates power factor from voltage/current behavior, and automatically switches capacitor banks to reduce reactive power. It is designed for small industrial or lab loads where low power factor increases losses and utility penalties. The display gives live electrical readings while relay-controlled capacitor stages correct the load.

Specifications

RoleHardware designer and firmware developer

MicrocontrollerArduino / ATmega328

SensorsVoltage sensorCurrent sensor

ModulesRelay moduleCapacitor bankLCD display

ProtocolsGPIOI2C

Tech tagsPower FactorCapacitor BankRelay ControlAC MeasurementEmbedded

Architecture

Sensors feed electrical data to the controller. Firmware decides the required correction stage and switches capacitors through relays while displaying real-time status.

Project photos

Automatic power factor corrector prototype — Power factor corrector prototype and display

Videos

Implementation details

Firmware

Firmware samples voltage/current inputs, estimates load condition, selects capacitor stages, updates LCD values, and prevents rapid relay chatter through timing logic.

PCB

Prototype wiring separates measurement, relay switching, and display/control sections for easier debugging.

Power

AC measurement and capacitor switching require proper isolation, fusing, discharge paths, and safe enclosure design for field use.

Components / BOM

Arduino / ATmega328 controller, Voltage sensing stage, Current sensing stage, Relay module, Capacitor bank, LCD display

Engineering challenges

Accurate sensing under noisy AC conditions and safe switching of capacitor stages were the main engineering concerns.

Solutions

Implemented staged correction, display feedback, and switching delays to make the prototype stable during load changes.

Results & metrics

Demonstrates automatic correction behavior and live monitoring on a bench prototype.

Future improvements

Add calibrated RMS measurement IC, data logging, Modbus/RS485, enclosure, and protection circuitry.