Woodward 9905-990 | 2301A Series Digital Speed Controller for Industrial Turbines

Description

Product Overview

Key Technical Specifications

• Input Signals:
  • 16 contact inputs (4 dedicated for emergency stops/safety functions, 12 programmable for custom logic).
  • 6 programmable current inputs (4-20 mA) for connecting to field instruments (e.g., pressure transmitters, temperature sensors).
• Output Signals:
  • 0-10V DC analog output (for driving actuators/valves).
  • Relay outputs for alarm indication (e.g., overspeed, low oil pressure).
• Communication:
  • RS-232 serial port (for local configuration via PC).
  • Ethernet port (for remote monitoring/control via DCS/PLC using Modbus protocol).
• Environmental Ratings:
  • Operating temperature: -10°C to +60°C (14°F to 140°F).
  • Storage temperature: -40°C to +85°C (-40°F to 185°F).
  • Humidity: 95% non-condensing (up to 48 hours at 20-55°C).
  • Protection: IP56 (dust-tight, protected against strong water jets).
• Physical Characteristics:
  • Dimensions: ~15.2 cm × 5.1 cm × 20.3 cm (6 in × 2 in × 8 in).
  • Weight: ~0.7 kg (1.5 lbs).
• Certifications: CE, UL (compliant with international industrial safety standards).

  

  WOODWARD 9907-167

Field Application & Problem Solved

1. Precision Speed Control:
   The module uses adaptive PID algorithms​ to adjust turbine speed within ±0.25% of the setpoint—even during rapid load changes (e.g., grid frequency drops). This stability is critical for power plants, where frequency deviations can trigger grid penalties.
2. Load Sharing:
   For multi-turbine systems, the 9905-990 enables isochronous load sharing—distributing load evenly across turbines to optimize efficiency and reduce wear. For example, a refinery using the 9905-990 reduced turbine maintenance costs by 20% due to balanced load distribution.
3. Fault Protection:
   The module’s first-out indication​ feature logs the initial cause of a shutdown (e.g., overspeed, low oil pressure), reducing troubleshooting time by 50%. This is invaluable for minimizing downtime in critical processes like power generation.

• Power Generation: Controlling steam turbines in coal/gas-fired power plants to maintain grid frequency stability.
• Oil & Gas: Driving turbo expanders for gas separation (e.g., air separation units) with precise speed control.
• Manufacturing: Regulating compressor turbines in chemical plants to optimize process efficiency.

Installation & Maintenance Pitfalls (Expert Tips)

1. Validate Actuator Compatibility:
   • Confirm that the turbine’s actuators (e.g., steam inlet valves) are compatible with the 9905-990’s 0-10V DC output. Mismatched signals can lead to erratic control—we once resolved a turbine oscillation issue by replacing an incompatible actuator with a Woodward EPG series model.
2. Configure Input Signals Correctly:
   • The 6 programmable 4-20 mA inputs are susceptible to electromagnetic interference (EMI) from nearby motors or transformers. Use shielded twisted-pair cables and ground the shield at the module end to prevent signal corruption—this reduced noise-related errors by 80% in a chemical plant installation.
3. Test Communication Links:
   • After installation, test the RS-232/Ethernet communication links using Woodward’s 505View​ software to ensure data is transmitted correctly. This step prevents issues like “no data” errors during operation.
4. Perform Regular Calibration:
   • Calibrate the 9905-990 annually using a precision multimeter and signal generator. Check the input signals (4-20 mA) against the module’s display and adjust the PID gains if the speed deviation exceeds ±0.25%. We recommend using Woodward’s 505View​ software for real-time monitoring during calibration.

     

     WOODWARD 9907-167

Technical Deep Dive & Overview

1. Signal Acquisition:
   The module receives input signals from:
   • Speed sensors​ (magnetic pickups) monitoring turbine shaft rotation.
   • Field instruments​ (pressure/flow transmitters) measuring process variables.
   • Operator inputs​ (via the front-panel keypad) for setpoint adjustments.
2. Processing & Control:
   The microprocessor processes the input signals using PID (Proportional-Integral-Derivative)​ algorithms to calculate the required turbine speed. The adaptive nature of the algorithm allows it to adjust gains dynamically based on operating conditions (e.g., load changes, temperature variations).
3. Output & Actuation:
   The module sends a 0-10V DC control signal to the turbine’s actuators (e.g., steam inlet valves) to adjust the steam flow, thereby regulating speed and load. Simultaneously, it monitors for fault conditions (e.g., overspeed, low oil pressure) and triggers protective shutdowns if necessary.
4. Communication & Monitoring:
   The 9905-990 transmits real-time data (speed, load, fault status) to the plant DCS via Modbus RTU/Ethernet. Operators can use 505View​ software to visualize trends, adjust setpoints, and perform diagnostics remotely.

Final Notes