Woodward 9907-1228 CPC-II – Enhanced current-to-pressure converter for precise steam turbine valve control

The Woodward 9907-1228 is an enhanced CPC-II (Current-to-Pressure Converter) designed to translate a 4–20 mA command into a stable 0–10 bar hydraulic pressure. It’s typically used on single-acting steam turbine speed-control and stop/ratio valves where accuracy, response, and long service intervals matter. One thing I appreciate is how the enhanced “Silt Buster” logic keeps performance stable even when oil cleanliness isn’t perfect—something you run into in real plants.

Order Placement Process and Guarantees

• Warranty: 365 days from shipment
• Delivery: 1 week if in stock; no more than 1 month latest
• Payment: 50% advance; balance before delivery
• Express options: FedEx, UPS, DHL

Key Features

• 4–20 mA to 0–10 bar conversion – Proportional, isolated input drives stable hydraulic output up to 145 psi.
• Enhanced “Silt Buster” function – Adaptive purge logic helps clear ~40 μm contaminants without interrupting control.
• High accuracy and repeatability – Typical accuracy to ±0.2% of full scale; repeatability around 0.1% FS for tight valve positioning.
• Fast response – Sub-75 ms to 90% step is common, improving turbine load response and start-up sequences.
• Advanced control algorithms – PID with 11-point linearization improves low-flow and near-seat control behavior.
• Built-in diagnostics – Health/status monitoring, event history, and trending support predictive maintenance.
• Redundancy options – Dual 4–20 mA inputs with voting logic help maintain control if one source degrades.
• Rugged build – IP66 enclosure, wide operating temperature, and vibration/shock-tested for turbine skids.
• Service interface – RS-232 service port for configuration, testing, and calibration from a PC tool.

Technical Specifications

Application Fields

From my experience, the 9907-1228 fits best on single-acting steam turbine governor valves and intercept/stop valves where precise hydraulic pressure tracking is required. It’s also a solid choice for fast-trim industrial control loops that need stable I/P conversion with minimal drift. You might notice that Zone 2 / Class I, Div. 2 classified areas are supported when installed per the approvals, which expands where you can deploy it on brownfield turbine skids.

• Steam turbine speed and load control (single-acting servos)
• Industrial process actuators demanding 0–10 bar control pressure
• Upgrades from standard CPC-II and legacy I/H transducers (e.g., Voith E360 with adapter)
• Projects aiming to reduce maintenance through intelligent oil contamination handling

Advantages & Value

• Reliability in real-world oil conditions – The enhanced silt-handling routine maintains valve control stability between filter service intervals.
• Measurement-grade control – Low noise and tight linearization improve efficiency on turbines that run close to limits.
• Reduced downtime – Event logging and trend data typically shorten troubleshooting and support predictive maintenance plans.
• Lifecycle economics – Drop-in upgrade path from standard CPC-II or older I/H devices cuts engineering time and preserves piping.
• Compatibility – Works with standard 4–20 mA loops and common turbine control systems; RS-232 simplifies field service.

A maintenance lead at a 150 MW plant told us their governor valve hunts diminished after moving to the enhanced CPC-II profile—no other changes made—so the upgrade seems to pay off in many cases.

Installation & Maintenance

Install on a clean hydraulic circuit with proper venting and access for service. Any orientation is acceptable; most teams mount on a rigid bracket or panel near the valve manifold.

• Cabinet/Environment – IP66 enclosure; allow airflow around the unit and keep cable bend radii within spec.
• Hydraulic plumbing – Flush lines before hookup; connect S (supply), C (control), T (return); verify supply ≈10 bar and return ≤2 bar.
• Fasteners – 4 × M10 with ≥16 mm thread engagement; torque ~60–80 N·m on suitable grade bolts.
• Power – 18–32 VDC with local switch/breaker and earth ground; allow for short inrush up to ~8 A during actuation.
• Signal wiring – Shielded twisted pairs for 4–20 mA; keep shields properly terminated; minimize exposed braid (≤50 mm).
• Service/Calibration – Use the RS-232 PC tool for tuning, 11-point linearization, and verification of silt/cleaning parameters.

Routine maintenance typically includes external filter element service, oil cleanliness checks (target ISO 20/16 or better), connector inspection, and periodic calibration. Firmware updates—when applicable—should be performed during planned outages after a full configuration backup.

Quality & Certifications

• CE compliance: EMC Directive 2014/30/EU; Machinery Directive 2006/42/EC; Pressure Equipment Directive 2014/68/EU
• ATEX: II 3 G Ex nA IIC T4 Gc (Zone 2); IECEx equivalent
• North America: CSA Class I, Div. 2, Groups A, B, C, D; T4
• EAC conformity for Customs Union markets
• EMC: EN 61000-6-2 / EN 61000-6-4
• Functional safety: SIL-2 capable in approved system architectures
• Warranty: 365 days from shipment (supplier warranty)

Model Positioning & Upgrade Notes

The 9907-1228 is the enhanced, low-pressure CPC-II variant for demanding, non-incendive applications typically found on steam turbine skids. If you’re upgrading from a standard CPC-II (e.g., 9907‑1200 series) or replacing older I/H transducers like Voith E360, this model usually shortens commissioning due to familiar I/O and mounting practices, while delivering tighter control and more robust diagnostics.