Woodward 9905-204 | 2301A Load Sharing and Speed Control Module

The Woodward 9905-204 is an industrial digital speed control and load sharing governor module from the 2301A product series. It is engineered to control the speed and load of diesel or gas engines, as well as steam or gas turbines. This module is equipped with advanced internal circuitry that allows it to operate in either isochronous or droop modes, enabling multiple parallel-connected generator sets to share proportional electrical loads while keeping the overall grid frequency completely stable.

⚙️ Product Specifications

• 🧩 Manufacturer: Woodward
• 🔢 Model Number: 9905-204
• 🏷️ 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 Driving Output: 0–200 mA continuous differential current loop

🏭 Applications

• ⚡ Parallel Generator Networks: Synchronizing and balancing kilowatt (kW) distribution across multi-engine power stations.
• 🚢 Marine Electrical Grids: Main propulsion tracking and auxiliary generator speed management on commercial vessels.
• 🛢️ Oil & Gas Field Utilities: Managing heavy load transitions on prime movers operating in refinery and drilling environments.
• 🏭 Co-Generation Facilities: Stabilizing localized grid networks by matching local generator output with public utility lines.

🛑 Power Sequencing (Startup/Shutdown)

🔌 Power-On Sequence

• 🔧 Ensure that the 9905-204 module metal casing is properly grounded to the control panel’s sub-plate.
• 🔧 Check that the potential transformer (PT) and current transformer (CT) wiring paths are secure and free of ground faults.
• 🔧 Verify that the remote system operator switch is set to the STOP position.
• ⚡ Energize the external 24 VDC power supply to deliver current to the module.
• 🟢 Observe the status indicator lights on the front plate; confirm that the power LED stays lit, indicating that the unit has completed its internal power-on self-test.

🔌 Power-Off Sequence

• 🛑 Isolate the generator from the common electrical bus by opening the main circuit breaker under a zero-load state.
• 🛑 Bring the prime mover down to its standard low-idle speed to allow a proper thermal cool-down period.
• 🛑 Toggle the remote Stop contact to zero the current loop to the actuator, safely halting fuel flow to the engine.
• ⚡ Once the MPU verifies 0 RPM and the engine is completely stationary, turn off the primary 24 VDC supply breaker.

🏃 Normal Operating Procedure (Step-by-Step)

• Step 1: Verify through the master panel display or monitoring terminal that the 9905-204 shows no active line faults or system alarms.
• Step 2: Engage the auxiliary equipment and start the prime mover cranking sequence from the main control station.
• Step 3: The module reads initial tracking speed from the Magnetic Pickup (MPU) and automatically ramps the actuator to the configured start-fuel limit.
• Step 4: As the machine hits stable combustion, verify that the governor carries the system past the idle ramp up to rated synchronization speed.
• Step 5: Close the parallel breaker; the module will instantly use its load-sharing lines to dynamically balance the real power load with neighboring generator units.

🔧 Parameter Settings & Modification

• 💻 Interface Method: Configuration tunings are performed 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 increase loop crispness, or counter-clockwise if you notice over-correction or mechanical oscillations.
• 💻 Load Gain Adjustment: Tune the Load Gain pot while running parallel systems to ensure the kilowatt output splits proportionally based on the 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 droop required from zero load to full load (typically 3% to 5%).

❓ Frequently Asked Questions (Q&A)

• Q: The generator runs fine alone but sheds its entire load immediately when paralleled. What is wrong?
  • A: This symptom usually points to an open circuit or reversed polarity on the 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 operate?
  • A: The 9905-204 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?
  • A: No. The 9905-204 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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