Woodward 9905-797 | 2301A Load Sharing and Speed Control Module

The Woodward 9905-797 is an industrial digital speed control and load sharing governor module from the globally trusted 2301A product family. It is precisely engineered to control the speed and proportional load distribution of industrial diesel or gas engines, as well as steam or gas turbines. The module features integrated circuitry that allows it to operate in either isochronous or droop modes, enabling multiple parallel-connected generator sets to smoothly split electrical loads without causing frequency fluctuations across the common bus bar.

⚙️ Product Specifications

• 🧩 Manufacturer: Woodward
• 🔢 Model Number: 9905-797
• 🏷️ Product Type: 2301A Load Sharing & Speed Control System
• 📐 Dimensions: 27.3 cm x 18.4 cm x 6.4 cm (10.75″ x 7.24″ x 2.52″)
• ⚖️ Weight: 2.15 kg (4.74 lbs)
• 🗺️ Country of Origin: USA
• ⚡ Operating Power Supply: 18–40 VDC (24 VDC Nominal)
• 📉 Power Consumption: 15 Watts maximum
• 🔌 Actuator Output Current: 0–200 mA continuous differential current loop

🏭 Applications

• ⚡ Multi-Engine Power Stations: Synchronizing and balancing kilowatt (kW) distribution across parallel generator arrays.
• 🚢 Marine Electrical Infrastructure: Main propulsion engine tracking and auxiliary generator speed management on commercial vessels.
• 🛢️ Petrochemical Substations: Regulating prime movers experiencing heavy load transitions in refinery and drilling environments.
• 🏭 Co-Generation Utilities: Stabilizing localized plant grids by precisely matching local generator output with public utility power lines.

🛑 Power Sequencing (Startup/Shutdown)

🔌 Power-On Sequence

• 🔧 Verify that the 9905-797 module’s chassis frame is properly grounded to the control panel enclosure backplate.
• 🔧 Double-check that all Potential Transformer (PT) and Current Transformer (CT) sensory connections are tight and free of ground faults.
• 🔧 Ensure that the master manual runtime switch is set to the STOP position.
• ⚡ Energize the external 24 VDC power supply to send power to the module’s primary terminals.
• 🟢 Check the faceplate diagnostic LEDs; a solid green power lamp confirms the unit has completed its internal power-on self-test successfully.

🔌 Power-Off Sequence

• 🛑 Open the main generator breaker under a zero-load state to fully isolate the generator from the common electrical bus.
• 🛑 Bring the prime mover down to its low-idle speed to allow a standard mechanical and thermal cool-down period.
• 🛑 Trigger the remote Stop contact to zero the current loop to the actuator, safely cutting off fuel flow to halt rotation.
• ⚡ Once the speed signal registers 0 RPM and the engine is completely stationary, turn off the main 24 VDC supply breaker.

🏃 Normal Operating Procedure (Step-by-Step)

• Step 1: Confirm that the 9905-797 indicates a healthy runtime baseline with no active line faults or system alarm status registers triggered.
• Step 2: Start auxiliary fuel/lubrication systems and initiate the prime mover cranking sequence from the central operator station.
• Step 3: The module reads the incoming frequency from the Magnetic Pickup (MPU) and automatically positions the actuator to the pre-programmed start-fuel limit.
• Step 4: As the machine catches and fires, verify that the governor stabilizes the system past the idle ramp and directly up to rated synchronization speed.
• Step 5: Close the parallel bus breaker; the module will instantly utilize its active load-sharing lines to dynamically balance real power with adjacent generator units.

🔧 Parameter Settings & Modification

• 💻 Interface Method: Configuration tunings are performed manually using the multi-turn potentiometers located beneath the front access panel cover.
• 💻 PID Response Tuning: Adjust the Proportional Gain and Reset (Integral) pots to eliminate engine hunting. Turn slowly clockwise to crisp up tracking response times, or counter-clockwise if you notice over-correction or speed oscillations.
• 💻 Load Gain Adjustment: Tune the Load Gain pot while running systems in parallel to guarantee that the kilowatt output splits proportionally based on each generator’s overall capacity rating.
• 💻 Droop Selection: If running in a droop configuration, adjust the dedicated Droop potentiometer to establish the exact percentage of speed reduction required from zero load to full load (typically 3% to 5%).

❓ Frequently Asked Questions (Q&A)

• Q: The generator runs perfectly alone but drops its load entirely the moment it parallels. Why?
  • A: This symptom usually points to an open circuit or reversed polarity on the twisted-pair load-sharing lines linking the parallel modules, or improperly phased CT/PT voltage sensing lines.
• Q: What is the minimum signal required from the MPU for this module to function?
  • A: The 9905-797 requires a minimum speed sensor input of 1.0 VAC RMS during engine cranking. Lower voltages will result in a loss-of-speed fault, preventing the actuator from opening.
• Q: Can this unit accept alternating current (AC) directly for its main power supply input?
  • A: No. The 9905-797 runs exclusively on low-voltage direct current (18–40 VDC). Applying standard AC line voltage directly to the power terminals will permanently damage the internal circuit boards.

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