Nam Theun 2 Power Company Limited operates a power generation facility in Laos, where reliable turbine overspeed protection is essential for safe and continuous operation. A robust overspeed protection system is critical to safeguard rotating equipment and ensure operational safety and availability.
To enhance reliability, accuracy, and long-term maintainability, the existing Jaquet T401 overspeed detection system was replaced with a modern Overspeed Detection System (ODS) panel. The project was carried out by TriSystems, including supply, installation, configuration, and testing of the new turbine overspeed protection system.
Challenge
The existing turbine overspeed protection system had become outdated, limiting flexibility, accuracy, and maintainability. At the same time, the plant required a highly reliable overspeed detection system to protect critical rotating equipment across multiple generating units.
The main challenges included:
- Replacing the legacy Jaquet T401 with a modern overspeed protection system
- Meeting strict turbine safety requirements through a 2-out-of-3 (2oo3) voting structure
- Ensuring accurate and fast turbine overspeed detection
- Achieving seamless integration with SCADA and EWS systems
In addition, the project had to be executed with minimal disruption during installation, testing, and commissioning.
Solution
To meet these requirements, a new Overspeed Detection System (ODS) panel was delivered as a modern turbine protection solution. The system is based on advanced SpeedSys modules, enabling accurate RPM measurement, configurable setpoints, and continuous speed monitoring.
A redundant 2oo3 voting architecture was implemented to ensure high-reliability overspeed protection and eliminate the risk of unsafe conditions. The system was fully integrated with existing SCADA and EWS environments, ensuring seamless monitoring and control of turbine speed and trip signals.
Execution
The overspeed protection system was installed, configured, and validated through a structured Site Acceptance Testing (SAT) process. This ensured that all functional and performance requirements were met.
The execution included inspection, configuration validation, functional testing, trip simulation, and full SCADA/EWS integration testing. All activities were carried out in compliance with project specifications and quality standards, ensuring a controlled and reliable commissioning process.
The structured SAT approach played a key role in validating system performance and achieving full client acceptance without critical outstanding issues.
Impact
The new Overspeed Detection System was successfully commissioned and is now fully operational across all generating units. The upgraded turbine overspeed protection system delivers accurate speed detection and reliable overspeed trip functionality.
During testing, turbine shutdown mechanisms were consistently activated under simulated overspeed conditions, confirming the effectiveness of the turbine safety system.
As a result, the plant benefits from:
- Improved reliability and maintainability of the overspeed protection system
- Fast and accurate overspeed detection and trip response
- Seamless integration with SCADA and existing plant systems
- Increased safety, availability, and operational confidence
The project also received positive client feedback on technical support, coordination, and overall delivery quality.
Conclusion
This project demonstrates how a legacy overspeed detection system can be successfully replaced with a modern and redundant overspeed protection system. By combining SpeedSys technology with a robust 2oo3 voting architecture and a structured SAT approach, the project significantly improved turbine safety, reliability, and maintainability.
The result is a modern, reliable, and future-proof overspeed protection solution that ensures safe operation of critical rotating equipment at the Nam Theun 2 power plant, delivering stronger safety, higher availability, and long-term peace of mind.
