Website Monitoring System for Automatic Transfer Switch (ATS) Using the MQTT Protocol

Abstract

Reliable automatic source transfer in distributed installations requires local switching and remote observability of source status and electrical parameters. This study designs, implements, and evaluates an Internet of Things (IoT)-based website monitoring system for an Automatic Transfer Switch (ATS) using the MQTT protocol. The system adopts a three-layer IoT architecture comprising perception, network, and application layers. An ESP32 performs data acquisition, local switching logic, and wireless communication; PZEM-004T and PZEM-017 modules measure AC and DC parameters; and Solid State Relays support switching between the main supply and backup battery. Sensor readings are acquired through Modbus RTU, serialized in JSON, published to an MQTT broker, stored in a database, and visualized through a bidirectional web dashboard with control-command capability. Performance evaluation was limited to prototype tests under the tested network conditions and focused on monitoring responsiveness rather than field-level robustness or protection performance. The evaluated indicators were Modbus RTU response delay, MQTT transmission delay, Packet Delivery Ratio, dashboard update delay, and estimated end-to-end latency. Results showed an average Modbus RTU delay of 46.12 ms, MQTT delay of 67.6 ms, Packet Delivery Ratio of 98.63%, dashboard update delay of 0.497 s, and end-to-end latency of 610.7 ms. Although MAPE was specified for sensor accuracy evaluation, AC and DC accuracy values were not reported. These findings indicate that the architecture can support responsive near-real-time ATS monitoring at the prototype level, while actual source-transfer response, long-term reliability, and operational impacts require further validation.