Product Core Brief
- Model: 9907-1200
- Brand: WOODWARD
- Series: CPC-II second-generation current-to-pressure converter family
- Core Function: Convert 4–20 mA analog control signals to proportional 0–10 bar hydraulic output to position single-acting steam turbine governor and bypass valve servos.
- Product Type: Field-mount electrohydraulic I/P converter (standalone explosion-proof unit)
- Key Specs: 0–10 bar hydraulic output range | Dual redundant 4–20 mA analog inputs | Spring return fail-safe to closed valve position | SIL 2 safety certified
Product Introduction
The WOODWARD 9907-1200 is a rugged explosion-proof I/P converter built exclusively for critical steam turbine electrohydraulic actuation systems. It translates DCS or turbine controller analog setpoints directly to hydraulic pressure without intermediate signal conditioning hardware.This unit outperforms generic industrial I/P converters with integrated self-cleaning fluid ports and corrosion-resistant aluminum housing for contaminated turbine lube oil circuits. OEM field data records a 54,000 hour MTBF under continuous 50 °C turbine cabinet runtime.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Analog Control Input | Single or dual redundant 4–20 mA DC signals |
| Hydraulic Output Pressure Range | 0 bar to 10 bar (0 psi to 145 psi) |
| Full-Scale Control Accuracy | ±0.2 % of calibrated range; repeatability ±0.1 % FS |
| Operating Supply Voltage | 18 VDC to 32 VDC (24 VDC nominal), 1 A steady-state draw |
| Max Hydraulic Supply Pressure | 25 bar; recommended operating pressure below 17.5 bar |
| Fail-Safe Mechanism | Internal spring return drives valve to closed position on power loss |
| Enclosure Environmental Rating | NEMA 4X / IP66 dust and splash resistant; ATEX IECEx Zone 2 certified |
| Safety Integrity Level | SIL 2 for turbine critical control loops |
| Mechanical Mount Options | 35 mm DIN rail or four-point panel surface mounting |
| Material Construction | Cast aluminum corrosion-resistant housing; self-cleaning hydraulic port geometry |
| Continuous Operating Ambient Temp | -40 °C to +85 °C full rated performance; hydraulic fluid range matching ambient limits |
| Storage Temperature Range | -40 °C to +85 °C, 5–95 % RH non-condensing |
| Integrated Protection Circuits | Input current surge clamping, reverse supply polarity lockout, hydraulic overpressure limiting |
| Certifications | CE, ATEX Zone 2, IECEx, SIL 2, EN61000 Class A industrial EMC filtering |
| Net Unit Weight | 0.35 kg |
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Cross-reference serial numbers against Woodward OEM trace databases; inspect aluminum housing for casting cracks, electrical terminal threads for stripping, hydraulic port fittings for burrs. Photograph electrical and hydraulic pin/port layout for turbine field cabinet wiring reference.
- Live Functional Test: Mount the unit to a hydraulic test bench paired with a programmable 4–20 mA signal generator and calibrated pressure transducer; run a continuous 24-hour cyclic 4–20 mA ramp test across full output pressure range. Log hydraulic output stability with a Fluke 115 digital multimeter and precision pressure gauge for the full duration.
- Electrical Parameter Test: Perform a 1000 V Megger insulation resistance test between analog input field circuits and unit housing ground; pass threshold set at >10 MΩ. Verify redundant input automatic switchover with <15 ms delay when primary 4–20 mA signal is cut.
- Calibration Verification: Read and record factory pressure span and zero calibration offsets; document default redundant input priority logic settings for customer turbine site reference.
- Final QC & Packaging: Wipe electrical terminal contact surfaces to remove oxidation; seal the unit inside an anti-static foam bag, affix a dated QC Pass label listing all completed electrical and hydraulic test metrics before rigid shock-resistant carton packing.
Replacement Pitfall Guide
❗ Pressure Range Model Mismatch Risk: 9907-1197 / 9907-1198 25 bar CPC-II variants cannot replace this 10 bar unit. Installing a higher pressure model creates valve overtravel and potential actuator seal rupture during normal DCS setpoint operation. Confirm 0–10 bar part number before field removal.❗ Hydraulic Fluid Filtration Misconfiguration Risk: Fluid filtration coarser than 40 μm clogs the unit’s self-cleaning ports within weeks. Always install OEM-specified 24–40 μm β75 hydraulic filters upstream to prevent drift in output pressure regulation.❗ Analog Cable Shield Ground Misconfiguration Risk: Unshielded 4–20 mA field wiring run parallel to high-current generator excitation cabling injects EMI noise that causes continuous valve hunting. Use factory twisted-pair shielded analog assemblies, terminate shield ground at only the control cabinet terminal block end.❗ Field Cabinet Power Headroom Miscalculation Risk: A turbine cabinet with four of these I/P converters draws 4 A total from the VM310 24 V auxiliary supply. Calculate total load with a mandatory 20% power margin to avoid voltage sag during fast valve modulation transients.❗ Uncontrolled ESD Damage Risk: Dry turbine field cabinet air creates static charge buildup. Touch a grounded anti-static mat for three full seconds before handling the electrical terminal block; ungrounded contact destroys the low-tolerance analog signal conditioning ASIC.Keep these in mind and you’ll cut 90% of rework time.
Compatibility Matrix & Benchmarks
Compatibility Matrix
- 9907-1197 25 bar CPC-II I/P converter → 9907-1200 : Incompatible — mismatched hydraulic output range risks turbine actuator mechanical failure
- Woodward 505 / Flex500 turbine main controllers → 9907-1200 : Direct — accepts standard 4–20 mA analog output to drive the converter’s control input
- VM310 24 V cabinet auxiliary power supply → 9907-1200 : Direct — regulated 24 V output falls within the unit’s 18–32 V operating window without extra voltage conditioning
- 5X00241G02 Ovation HART analog output module → 9907-1200 : Direct — 4–20 mA AO loop output feeds the converter’s primary control input
- CML40.2-SP-330-NA-NNNN-NW Rexroth SERCOS motion PLC → 9907-1200 : Needs Adaptation — wire converter hydraulic deviation dry contacts to PLC digital inputs, map DCS valve setpoint registers via Modbus TCP polling
