565-01 Distributed Control System Fundamentals

When you complete this lesson, you will be able to describe the design and function of a typical distributed control system (DCS).

• Describe the functions of a typical distributed control system (DCS)
• List and briefly describe the main components or elements of a DCS
• Explain the use of a remote control panel in the DCS
• Discuss communications mediums available for use in DCS; list advantages and disadvantages of each choice
• Describe the purpose of a central control facility (control room) associated with a DCS
• Describe the functions of the human machine interface (HMI)
• Discuss the reasons for different levels of authority on various HMI stations
• Identify the functions of control, interface, and database software associated with DCS

565-02 Distributed Control System Components

When you complete this lesson, you will be able to list the components associated with a common distributed control system (DCS) and describe their functions.

• List and briefly describe plant instrumentation used to collect system parameter and equipment data to be used in a DCS
• Describe the general design and function of the following DCS components:
  • Instrumentation
  • Transmitters and input/output modules
  • Processors
  • Multiplexers
  • Electrical/computer buses
  • Human-machine interface
  • ­­­Control devices/actuators
• Discuss the flow of information through the DCS and describe how that information is used to monitor and control power plant systems, parameters, and equipment

565-03 Using Distributed Control System Diagrams

When you complete this lesson, you will be able to describe the basic symbols and parts of a logic diagram. You will also be able to explain how to use a DCS logic diagram as a troubleshooting tool.

• Identify basic logic symbols used in logic diagrams
• List the parts of a drawing title block
• Explain the purpose of a drawing legend
• Discuss permissives and interlocks associated with control systems
• Describe how a control loop maintains a parameter at its control setpoint
• Discuss the use of trip setpoints
• Describe how the feedback function in a control loop helps keep processes stable
• Describe trim and bias control logic features
• Discuss general troubleshooting steps and techniques

565-04 Power Plant Unit Control

When you complete this lesson, you will be able to describe the basic design and function of a boiler-following instrumentation and control system.

• Discuss the basic operation of a boiler-following distributive control system (DCS)
• Explain how changing power plant load affects steam temperature, pressure, and flow
• Describe how the DCS maintains parameters at their designed values when unit load changes
• Discuss the relationship between the following:
  • Fuel flow and associated unit parameters
  • Fuel flow, furnace draft, air flow, and excess oxygen
  • Feedwater flow, steam flow, unit load, and boiler drum level
• Identify operator responsibilities in controlling key operating parameters, systems, and equipment during normal operation