Woodward 9905-387 | ProAct III Digital Actuator Driver

The Woodward 9905-387 is an advanced, high-performance digital actuator driver and control module designed specifically for the ProAct III electric actuator series. It is engineered to provide precise, high-speed position and speed governance for large industrial gas engines, dual-fuel engines, and specialized mechanical drive turbines. By processing high-resolution speed and position feedback data, the module delivers specialized pulse-width modulated (PWM) current to govern high-torque actuator motor coils, ensuring stable performance during extreme load variations.

⚙️ Product Specifications

• 🧩 Manufacturer: Woodward
• 🔢 Model Number: 9905-387
• 🏷️ Product Type: ProAct III Actuator Driver / Digital Governor
• 📐 Dimensions: 28.5 cm x 17.5 cm x 6.2 cm (11.22″ x 6.89″ x 2.44″)
• ⚖️ Weight: 2.25 kg (4.96 lbs)
• 🗺️ Country of Origin: USA
• ⚡ Operating Input Voltage: 18–32 VDC (24 VDC Nominal)
• 📉 Peak Current Output: Up to 20 Amps (Optimized for heavy-duty ProAct III actuator coil inertia)
• 🛡️ Enclosure Rating: IP20 / Structural aluminum heat-sink chassis

🏭 Applications

• ⚡ Utility Power Generation: Managing precise fuel-valve positioning for large-scale natural gas and dual-fuel power generator sets.
• 🛢️ Industrial Gas Compression: Controlling heavy-duty throttle valves on high-pressure pipeline gas compressors.
• 🚢 Commercial Marine Propulsion: Managing rapid throttle transitions for high-output marine propulsion engines and auxiliary generators.
• 🏭 Large Scale Cogeneration: Stabilizing frequency and load sharing for decentralized thermal-electric plants.

🛑 Power Sequencing (Startup/Shutdown)

🔌 Power-On Sequence

• 🔧 Confirm that all high-current power distribution wires and actuator terminal connections are torqued according to specifications to prevent arcing.
• 🔧 Ensure that the physical linkage between the ProAct III actuator and the fuel valve is uninhibited and moves freely throughout its full stroke.
• 🔧 Set the remote system master Run/Stop control to the STOP state.
• ⚡ Apply the main 24 VDC industrial power supply to the module’s power input terminals.
• 🟢 Observe the status LED matrix on the faceplate; a solid power indicator confirms that the internal diagnostic logic is active and the unit is ready for command.

🔌 Power-Off Sequence

• 🛑 Lower the engine speed to its idle setpoint and observe the manufacturer-defined thermal cool-down cycle.
• 🛑 Cycle the remote Stop command to tell the driver to move the actuator to the absolute zero-fuel/shutoff position.
• 🛑 Wait for the mechanical system to come to a full stop (0 RPM confirmed via MPU feedback).
• ⚡ Disconnect the upstream 24 VDC power supply circuit breaker to safely isolate the driver module.

🏃 Normal Operating Procedure (Step-by-Step)

• Step 1: Verify through the plant HMI or local control station that the 9905-387 reports no active faults or high-current warnings.
• Step 2: Trigger the automated engine start cycle from your host PLC or Distributed Control System (DCS).
• Step 3: The module reads the MPU frequency input as the engine cranks, instantly positioning the actuator to the configured start-fuel position limit.
• Step 4: As the engine catches and begins to accelerate, the module safely ramps fuel delivery through the idle window up to the rated operating speed.
• Step 5: Monitor live operational performance during load steps to verify that the driver maintains target speed with minimal settling time.

🔧 Parameter Settings & Modification

• 💻 Interface Method: Configuration is performed via integrated multi-turn faceplate potentiometers or through a handheld configuration display connected to the serial port.
• 💻 Dynamic Response Tuning: Use the Proportional Gain and Reset (Integral) pots to tune the loop responsiveness. Turn clockwise to increase speed sensitivity or counter-clockwise if the system experiences mechanical hunting.
• 💻 Fuel Limit Tuning: Set the Maximum and Minimum fuel restrictions to protect the system against mechanical over-stroking or bottoming-out against valve stops.
• 💻 Saving Parameters: Ensure all modified control register values are manually updated to the non-volatile memory block before executing a module power cycle.

❓ Frequently Asked Questions (Q&A)

• Q: The driver housing gets quite hot during operation. Is this a failure?
  • A: ProAct III drivers handle high-current transients for large actuators, naturally producing heat. Ensure the unit is mounted on a heat-sink surface with adequate airflow.
• Q: What protection is in place if the actuator position feedback wire breaks?
  • A: The 9905-387 continuously monitors position feedback. If a loss of signal is detected, the module immediately enters a “failsafe” mode, cutting actuator current to zero to safely shut the fuel valve.
• Q: Is this driver module backward compatible with older ProAct I/II actuators?
  • A: No. The 9905-387 is specifically engineered for the unique electrical impedance and power dynamics of the ProAct III family. Mismatched hardware may cause over-current faults or actuator damage.

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