WOODWARD 8901-457 Current-Pressure (I/P) Converter
the Woodward 8901-457 is a high-precision Current-to-Pressure (I/P) Transducer, specifically designed for industrial turbine and engine control applications.
It acts as the critical interface between electronic control systems and pneumatic actuators, converting a standard electrical signal into a proportional pneumatic output to position valves or fuel racks.
Technical Parameter Table
| Parameter | Specification |
| Model Number | 8901-457 |
| Input Signal | 4–20 mA (Standard) |
| Output Pressure Range | 3–15 psi (0.2–1.0 bar) |
| Supply Pressure | 20 psi (1.4 bar) recommended; Max 50 psi |
| Accuracy | < ±0.5% of span |
| Linearity | < ±1.0% of span |
| Air Consumption | < 0.11 SCFM at 20 psi supply |
| Operating Temperature | -40°C to +85°C |
| Enclosure Rating | NEMA 4X / IP65 |
| Weight | Approximately 1.1 kg (2.4 lbs) |
Related Models
The 8901-457 is often utilized alongside these Woodward components:
8200-1300: 505 Series Digital Governor (provides the 4-20mA control signal).1
9907-162: 505 Turbine Controller.2
ProTech-GII: Overspeed protection systems that may trigger the I/P transducer for emergency shutdown.3
CPC II: Current-to-Pressure Converter (a more modern, high-precision electronic alternative).
Application Cases
Steam Turbine Control: Regulating the position of the steam governor valve to maintain constant speed or load.
Gas Turbine Fuel Systems: Controlling the fuel metering valves through pneumatic actuation.
Process Industry Valves: Used in refineries and chemical plants to control large-scale pneumatic control valves where electrical-only actuators are impractical.
Boiler Feedwater Systems: Managing the modulation of feedwater valves based on boiler demand.
8901-457
Product Advantages and Features
Explosion-Proof Design: Certified for use in hazardous areas (Class I, Div 1), making it ideal for oil and gas environments.
Vibration Resistance: Specifically engineered to be mounted directly on or near high-vibration equipment like turbines and engines.
High Flow Capacity: Delivers high pneumatic flow rates, allowing for faster response times in large actuators.
Low Air Consumption: Optimized internal pilot valves minimize the amount of compressed air wasted during steady-state operation.
Field Adjustable: Includes zero and span adjustments that are easily accessible for calibration during commissioning.
8901-457
Other Models in the Same Series
The Woodward 8900/8901 family includes various pressure and signal configurations:
8901-456: Variant with 6–30 psi output range.
8901-458: High-pressure output variant for heavy-duty actuators.
8901-460: Model with internal pressure feedback for enhanced stability.
8910 Series: Low-cost variants for non-hazardous locations.
Introduction
The Woodward 8901-457 is a rugged, field-proven I/P transducer that bridges the gap between digital control logic and mechanical execution.
By translating a 4-20 mA current signal into a highly accurate 3-15 psi pneumatic signal, it allows sophisticated electronic governors to control heavy pneumatic machinery with extreme precision.
Its NEMA 4X housing and vibration-dampened internals ensure a long service life even when exposed to the corrosive and turbulent atmospheres of power plants and refineries.