505 Digital Control for Steam Turbines

Applicatons

The 505 controller is designed to operate industrial steam turbines of all sizes and applications. This steam turbine controller includes specifically designed algorithms and logic to start, stop, control, and protect industrial steam turbines or turbo-expanders, driving generators, compressors, pumps, or industrial fans.

The 505 control’s unique PID structure makes it ideal for applications where it is required to control steam plant parameters like turbine speed, turbine load, turbine inlet header pressure, exhaust header pressure, or tie-line power.

The control’s special PID-to-PID logic allows stable control during normal turbine operation and bumpless control mode transfers during plant upsets, minimizing process over- or undershoot conditions. The 505 controller senses turbine speed via passive or active speed probes and controls the steam turbine through one or two (split-range) actuators connected to the turbine inlet steam valves.

The 505 controller also includes the following turbine protection functions to ensure that the turbine or its driven load (compressor, pump, generator) is not operated outside of its designed limits:

• 3 Critical speed avoidance bands
• Overspeed anticipation and shutdown protection
• Configurable under- or over-pressure shutdown logic
• Minimum and maximum speed and load settings

Ethernet and serial communications allow users to easily connect the 505 into the plant or process control system. All controller inputs, outputs, and statuses can be monitored, and all start/stop or enable/disable commands can be given through industry standard Modbus ® * TCP or OPC protocols. The 505 uses SNTP (synchronized network time protocol) over Ethernet to allow users to synchronize the 505’s real-time clock to the plant distributed control system.

* Modbus is a trademark of Schneider Automation Inc.

Description

The 505 control is packaged in an industrial hardened enclosure designed to be mounted within a system control panel located in a plant control room or next to the turbine. The control’s front panel serves as both a programming station and operator control panel (OCP). This user-friendly front panel allows engineers to access and program the unit to the specific plant’s requirements, and plant operators to easily start/stop the turbine and enable/disable any control mode. Password security is used to protect all unit program mode settings. The controller’s 8.4-inch (21 cm) graphical display allows operators to view actual and setpoint values from the same screen, simplifying turbine operation.

Turbine interface input and output wiring access is located on the controller’s lower back panel. Un-pluggable terminal blocks allow for easy system installation, troubleshooting, and replacement.