Description
The Woodward 9905-973 is a microprocessor-based digital governor designed for the precise control and protection of extraction steam turbines. As part of the specialized 505E series, this controller is engineered to simultaneously manage turbine speed (or load) and extraction or admission steam pressure. By executing complex decoupling algorithms, it ensures that adjustments in extraction steam demand do not cause unstable fluctuations in turbine speed or electrical power output.
Product Specifications
- Model Number: 9905-973 (505E Series)
- Manufacturer: Woodward
- Control Application: Extraction / Admission Steam Turbines
- Input Voltage Range: 18–32 VDC (Standard Industrial Power)
- Speed Sensing Inputs: 2 Redundant Magnetic Pickup (MPU) or Proximity Probe channels
- Analog Inputs: 6 Configurable 4–20 mA inputs (for Extraction Pressure, Remote Speed, etc.)
- Actuator Outputs: 2 Configurable outputs (typically 4–20 mA or 20–160 mA for High Pressure and Extraction valves)
- Communication: Dual RS-232 / RS-422 / RS-485 Modbus RTU ports
- Operating Temperature: -25°C to +65°C
- Dimensions: 483mm x 177mm x 103mm (19-inch Rack Mount Chassis)
- Weight: 3.8 kg (8.38 lbs)
- Country of Origin: USA
Application Fields
The 9905-973 is primarily utilized in industrial co-generation facilities where both electrical power and process steam are required:
- Chemical and petrochemical processing plants managing variable header pressures.
- Pulp and paper mills utilizing low-pressure extraction steam for drying processes.
- District heating systems utilizing extraction steam for municipal heating grids.
- District power generation facilities featuring complex steam distribution loops.
Usage Instructions
Installation of the Woodward 9905-973 must be performed within an industrial enclosure providing protection against excessive moisture and dust. Prior to powering the unit, ensure all field sensors—specifically the redundant MPUs and pressure transmitters—are wired using shielded twisted-pair cables to prevent signal noise. During initial configuration, the technician must define the turbine’s operating envelope, including the maximum extraction limit and valve relationship maps. Use the front-panel membrane keypad to navigate to the “Configure Mode” for safety interlock logic and “Service Mode” for fine-tuning the proportional-integral-derivative (PID) dynamics of the speed and pressure loops.
Frequently Asked Questions (Q&A)
Q: What is the purpose of the “Decoupled” control logic in the 505E? A: In an extraction turbine, changing the position of the extraction valve affects the steam flow to the rear stages, which alters speed or power output. The 9905-973 automatically adjusts both the high-pressure and extraction valves simultaneously to satisfy the new pressure demand without altering the turbine speed or load.
Q: Can this unit handle admission steam instead of extraction steam? A: Yes. The 505E architecture is highly flexible and can be configured through the software menus to regulate systems that inject (admit) low-pressure steam into the turbine rather than extracting it.
Q: How does the module handle an overspeed event? A: The module contains internal, independent overspeed protection logic. If the speed signal exceeds the pre-programmed trip threshold, the unit instantly drops its actuator outputs to zero mA, causing the steam stop valves to close completely.
Related Model Recommendations
- Woodward 9905-971 (Standard 505 Steam Turbine Control)
- Woodward 9907-164 (505E Field-Mount Version)
- Woodward 8200-1302 (Peak 150 Digital Governor)
- Woodward 5466-1035 (MicroNet TMR Controller)
- Woodward 9907-162 (505 NextGen Controller)
