The Tricon-based feedwater control system architecture is shown in Figure 1 on the next page.
This basic architecture can be adapted to satisfy existing plant-specific field elements and wiring
requirements, any additional field element requirements, existing auto-manual feedwater control
procedures and strategies and communication requirements.
A typical feedwater control system consists of:
• Triconex® Tricon TMR system
• Triconex TriStation 1131 application development station
• Feedwater control application software
• Foxboro I/A Series® System or Wonderware® HMI (Human Machine Interface)
• Maintenance/Engineering workstation
• TriLogger software
Tricon TMR system
The Tricon is a Triple Module Redundant (TMR) architecture-based digital safety and control system.
The system is certified by TÜV (a world recognized, independent safety agency) at IEC (International
Electrotechnical Commission) SIL (Safety Integrity Level) 3 to be used for safety and critical control
applications in process control and other industries. The Tricon is also certified by the NRC (Nuclear
Regulatory Commission) to be used for safety (1E) and critical control applications in nuclear power plants.
The Tricon has three independent channels from the input terminal to the output terminal. Each input
is voted every scan by the three main processors (MPs), and the resultant voted input is provided to
the same application running in the three MPs. The outputs from the application running in each MP
go to the output modules where they are voted. The resultant voted output for each point goes to the
output terminal/field device.
The TMR architecture and design allows the Tricon system to perform its intended safety and control
functions in the presence of a single hardware fault. In addition, the design allows the Tricon to run in
TMR, DUAL or SINGLE mode, thus providing high availability (99.99%).
The built-in online diagnostics provide more than 99.9% fault coverage and isolate a fault to a specific module. The faulted module can be replaced with a new module online without affecting the feedwater system operation. The Tricon combines technology and architecture features to provide safety and control functions with the high reliability and high availability required for the safety and critical control applications in nuclear power plants.
The Tricon can be expanded from a single chassis system all the way up to a 15 chassis system with a wide variety of I/O and communications (COM) modules. Most feedwater control systems require a main chassis and two to three I/O expansion chassis, depending on the number of field elements and spare slot requirements for future expansion.
The COM modules provide the Tricon with the ability to interface to the existing plant computer, DCS systems, operator stations, etc. These COM modules provide the redundant, high speed, industry standard communication interfaces and protocols for transferring real-time plant data for control, monitoring, logging and trending for field diagnostics purposes. The I/O modules allow the Tricon to interface to different types of new and existing field devices. The I/O modules include: Analog Input, Analog Output, Thermocouple, Pulse Input, Digital Input and Digital Output.