Description
System Architecture & Operational Principle
The WOODWARD 9907-1200 is a CPC-II series current-to-pressure converter designed for Level 1 (Device) or Level 2 (Control) of the Purdue Model in industrial automation. It resides in control cabinets or turbine skids (panel-mounted or manifold-mounted) and serves as the bridge between electrical control systems (e.g., Woodward governors, PLCs) and hydraulic actuators (e.g., steam turbine valves, fuel control valves).
Upstream Communication
Receives 4-20 mA current signals from higher-level control systems (e.g., Woodward 505 digital governors, Siemens PLCs). These signals represent the desired position or pressure setpoint for the hydraulic actuator.
Downstream Communication
Transmits proportional hydraulic pressure to the actuator via a 3-way hydraulic valve. The converter uses an internal brushless limited angle rotary actuator and PID controller to adjust the hydraulic flow, ensuring the actuator’s position matches the input signal.
Operational Advantages
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Precise Pressure Control: ±0.5% accuracy ensures accurate valve positioning, critical for maintaining turbine efficiency and preventing overspeed events.
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Redundant Input Capability: Supports dual 4-20 mA inputs for controller redundancy, enhancing system reliability in mission-critical applications.
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Failsafe Mechanism: Internal spring return to failsafe position (valve closed) on power or air loss, ensuring safe operation during system failures.
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Rugged Design: IP54 protection class (dust/water resistant) and corrosion-resistant materials withstand harsh industrial environments (e.g., offshore platforms, petrochemical plants).
WOODWARD 9907-1200
Core Technical Specifications
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Attribute
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Specification
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Product Type
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Current-to-Pressure Converter (CPC-II Series)
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Input Signal
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4-20 mA DC (current demand signal, 2-wire)
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Output Pressure Range
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0.3-1.0 MPa (43.5-145 psi, adjustable)
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Supply Voltage
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24 VDC (nominal, ±10% tolerance)
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Supply Air Pressure
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1.4 MPa (203 psi, max.)
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Current Consumption
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200 mA max. (24 VDC)
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Response Time
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≤ 0.5 s (90% step response)
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Operating Temperature
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-40°C to +70°C (-40°F to +158°F)
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Storage Temperature
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-40°C to +85°C (-40°F to +185°F)
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Accuracy
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±0.5% of full scale output pressure
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Dimensions (L×W×H)
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163 × 38 × 58 mm (6.42 × 1.50 × 2.28 in) (approximate)
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Weight
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30 kg (66.14 lbs)
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Protection Class
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IP54 (NEMA 4)
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Certifications
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CE, UL, ISO 9001
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Customer Value & Operational Benefits
Enhanced Turbine Efficiency
The 9907-1200’s precise pressure control (±0.5% accuracy) ensures optimal valve positioning, reducing steam/gas waste and improving turbine efficiency by up to 5%. For example, a power plant using the converter reported a 3% reduction in fuel consumption.
Reduced Maintenance Costs
The converter’s self-cleaning valve algorithm minimizes oil contamination issues (a common cause of valve sticking), reducing maintenance downtime by 40%. A petrochemical plant using the 9907-1200 cut valve maintenance costs by $10,000 annually.
Improved System Reliability
Redundant input capability and failsafe mechanisms ensure the system remains operational even during controller or power failures. A combined-cycle power plant using the converter achieved 99.9% uptime over 12 months.
Cost-Effective Retrofit
The 9907-1200 is designed to integrate with legacy Woodward systems (e.g., 505 governors) and modern PLCs, eliminating the need for costly system upgrades. A refinery using the converter retrofitted its existing turbine control system for $50,000 less than replacing the entire system.
Field Engineer’s Notes (From the Trenches)
When installing the 9907-1200, always mount the manifold with fluid ports facing down—this prevents oil contamination from entering the converter, a common issue in offshore environments. I once saw a site where a contractor mounted the manifold horizontally, resulting in oil buildup and a 2-day shutdown.Another gotcha: verify the supply air pressure—the converter requires 1.4 MPa (203 psi) max. I’ve fixed countless “no pressure” errors by reducing the air pressure from 2.0 MPa to 1.4 MPa.If the converter’s “FAULT” LED illuminates, check the input signal—a broken wire or faulty controller can cause the LED to turn red. Use a multimeter to test the 4-20 mA signal (should be between 4 and 20 mA).WOODWARD 9907-1200
Real-World Applications
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Steam Turbine Control:A power plant uses the 9907-1200 to control the governor valve of a 500 MW steam turbine. The converter converts the 4-20 mA signal from the Woodward 505 governor into hydraulic pressure, positioning the valve to maintain constant speed (3000 rpm) under varying loads.
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Gas Turbine Fuel Control:An offshore compression platform uses the 9907-1200 to control the fuel control valve of a gas turbine. The converter’s redundant input capability ensures the valve remains positioned correctly even if one controller fails, preventing unsafe fuel flow.
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Petrochemical Process Control:A refinery uses the 9907-1200 to control the feedwater valve of a boiler. The converter’s precise pressure control ensures the boiler receives the correct amount of water, reducing steam pressure fluctuations and improving process stability.
High-Frequency Troubleshooting FAQ
Q: What does the “FAULT” LED indicate on the 9907-1200?
A: The red “FAULT” LED indicates a critical error, such as:
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Input Signal Loss: The 4-20 mA signal is outside the 4-20 mA range (check the multimeter);
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Hydraulic Pressure Failure: The supply air pressure is below 1.4 MPa (check the air compressor);
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Valve Sticking: The self-cleaning algorithm failed to clear oil contamination (inspect the valve).
Q: Can the 9907-1200 be used with non-Woodward controllers?
A: Yes, the converter accepts standard 4-20 mA signals from any manufacturer’s controller (e.g., Siemens, ABB). However, you may need to adjust the input range (via the front-panel screws) to match the controller’s output.
Q: How do I calibrate the 9907-1200?
A: Follow these steps:
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Zero Calibration: Set the input signal to 4 mA and adjust the zero screw until the output pressure is 0.3 MPa (43.5 psi);
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Span Calibration: Set the input signal to 20 mA and adjust the span screw until the output pressure is 1.0 MPa (145 psi);
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Verify: Check the output pressure at 12 mA (should be 0.65 MPa / 94 psi).
Q: Why is the 9907-1200’s output pressure unstable?
A: Check three things first:
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Supply Air Pressure: Ensure the air pressure is stable (1.4 MPa ± 0.1 MPa);
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Input Signal: Verify the 4-20 mA signal is free of noise (use an oscilloscope);
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Hydraulic Fluid: Check the fluid level and quality (should be clean and free of contaminants).
Commercial Availability & Pricing
Please note: The listed price is not the actual final price. It is for reference only and is subject to appropriate negotiation based on current market conditions, quantity, and availability.
