Enhancing Power System Reliability Using a Watchdog-Based SMPS Monitoring Framework in MAXDNA DCS

Abstract

In thermal power plant instrumentation systems, uninterrupted 24 V DC supply is critical for the reliable operation of control modules, field instruments, communication interfaces, and safety interlocks. However, most installations rely on multiple SMPS (Switched Mode Power Supply) units housed across several field panels, where online health monitoring is limited. Undetected SMPS failures may lead to card malfunction, instrument dropout, or complete panel failure. This paper presents a low-cost, effective, and scalable method of introducing real-time SMPS health monitoring by integrating potential-free fault contacts as digital inputs into the MAXDNA DCS system. A dedicated logic scheme and alarm philosophy were developed to generate instantaneous alerts for any single SMPS failure. The system was successfully implemented in a working thermal power plant, resulting in improved equipment protection, reduced troubleshooting time, and enhanced operational availability. The solution contributes significantly to predictive maintenance and serves as a replicable model for similar process industries.

Introduction

Reliable 24 V DC power is critical for Distributed Control Systems (DCS) and field instrumentation in thermal power plants. Traditionally, SMPS failures were often unnoticed due to redundancy, lack of centralized visibility, and manual inspection challenges, risking instrument and panel malfunctions.

This project implemented a real-time SMPS health monitoring system integrated into the MAXDNA DCS. Key steps included system assessment, signal acquisition design, SCADA/DCS integration, alarm logic development, and phased testing (cold, warm, live). Each SMPS’s fault contact was connected to DCS Digital Inputs, with alarms configured to immediately alert operators of any failure.

Implementation outcomes:

1. 100% online monitoring: All SMPS units can be tracked in real time through SCADA/DCS.

2. Faster failure response: Immediate alarms enable quick corrective actions, preventing downtime.

3. Prevention of equipment damage: Early detection avoided DCS card, communication module, and field instrument failures.

4. Enhanced operator experience: SCADA graphics provide color-coded, panel-wise visualization and a plant-wide SMPS dashboard.

The system improved reliability, operational awareness, and maintenance efficiency while aligning with proactive digital asset management practices.

Conclusion

The integration of SMPS fault contacts into MAXDNA DCS successfully established a real-time monitoring and alarm system for power supply health in the thermal power plant. This solution eliminated delays in identifying SMPS failures, thereby preventing potential breakdowns of DCS cards, communication modules, and field instruments. The project demonstrates how minor digital enhancements can yield significant reliability improvements. The approach is scalable, economically feasible, and can be replicated across various industrial sectors relying on 24 V DC control systems. The implementation aligns with modern maintenance philosophies, including condition-based and predictive monitoring.

References

[1] MAXDNA Distributed Control System – Hardware and Engineering Manuals, General Electric. [2] IEC 61131 & 61508 standards for control system reliability and safety. [3] “Switched Mode Power Supply Design and Operation,” Texas Instruments Technical Series. [4] Thermal Power Plant Instrumentation Guides – O&M Best Practices Reports (CEA, India). [5] OEM Operation Manual and Data Sheet.

Copyright

Copyright © 2025 Anupam Patnaik. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.