Woodward 9905-144 – 2301A Full Authority Speed Control

Product Overview

The 9905-144 is a Woodward 2301A Full Authority Speed Control designed to regulate the speed or load of diesel engines, gas engines, steam turbines, and gas turbines. It is a low-voltage, forward-acting controller with a 10–40 VDC supply and a 0–200 mA actuator output. The speed reference is provided through a 4–20 mA input, allowing the controller to respond to process or supervisory control signals. Woodward’s documentation also describes isochronous operation, with droop available through an externally wired potentiometer. An optional SPM synchronizer connection can be used for speed and phase matching. The unit is housed in a sheet-metal chassis with front-accessible adjustment potentiometers, making it particularly useful for maintaining legacy turbine and prime-mover control systems.

Technical Specifications — 9905-144

Woodward 9905-144

Woodward’s manual specifically identifies 9905-144 as the 10–40 VDC, 0–200 mA, 4–20 mA, forward-acting version of the 2301A controller.

Key Features and Benefits — 9905-144

• 10–40 VDC low-voltage power supply.
• 4–20 mA speed-setting input.
• 0–200 mA actuator output.
• Forward-acting control configuration.
• Isochronous speed-control capability.
• Adjustable droop through external circuitry.
• Optional SPM synchronizer connection.
• Suitable for turbine and engine governor applications.
• Front-accessible adjustment controls.

The distinction between forward- and reverse-acting versions is important when selecting a replacement. Woodward lists 9905-146 as the corresponding reverse-acting model, so the actuator behavior must be checked before substitution.

Related Models

9905-146: Reverse-acting 2301A version with the same general 10–40 VDC and 0–200 mA configuration.

9905-145: AC/DC-powered version with 88–131 VAC or 90–150 VDC supply.

9905-148: Forward-acting version using a 1–5 VDC speed-setting input rather than the 4–20 mA configuration.

9905-794: Forward-acting low-voltage version using a 0–20 mA actuator output and 1–5 VDC speed-setting input.

Installation and Maintenance — 9905-144

Before installation, verify the supply voltage, actuator coil requirements, speed-sensing arrangement, 4–20 mA reference signal, and forward-acting configuration. Record the existing potentiometer settings before removing the controller.

During maintenance, inspect terminal connections, actuator wiring, speed-sensing circuits, and the external droop/synchronizer wiring. Verify the control signal and actuator current independently before adjusting the governor. Personally, I would confirm the actuator type and fail-safe behavior first; an incorrect forward/reverse configuration can produce an unsafe response from the prime mover.

For turbine applications, an independent overspeed shutdown system should remain in place. The speed controller should not be treated as the sole protective device.

Product Warranty — 9905-144

Warranty coverage should be confirmed according to the supplied condition, such as new surplus, refurbished, repaired, or tested-used. For critical turbine-control spares, procurement records should include the complete part number, revision, serial number, inspection status, and warranty period.

When sourcing the Woodward 9905-144, verify the 10–40 VDC supply, 4–20 mA speed reference, 0–200 mA actuator output, and forward-acting configuration before purchase. Woodward also provides a product-history lookup service for verifying product-specific information using the equipment label and part number.