Woodward 9907-173 | Load Sharing and Speed Control Module

The Woodward 9907-173 is a specialized version of the industry-standard 2301A electronic governor platform. It is a dual-function control module engineered to manage both the speed of a prime mover and the proportional sharing of electrical load when the generator is connected in parallel with other units. By facilitating high-speed communication between multiple generator sets, the 9907-173 ensures that each engine carries its fair percentage of the total facility load, preventing individual units from becoming overloaded or “motored” by the rest of the system.

⚙️ Technical Parameters & Datasheet

(Note: System configuration, architectural, and mechanical constraints are presented below in a scannable, non-table format).

📦 Physical Specifications

• Dimensions: Approximately 224 mm x 178 mm x 64 mm (8.80 inches x 7.00 inches x 2.50 inches)
• Weight: Approximately 1.40 kg (3.10 lbs)
• Mounting: Panel-mount or cabinet sub-plate installation
• Operator Interface: Front-panel multi-turn potentiometers for “Speed,” “Gain,” “Reset,” “Load Gain,” and “Load Limit” calibration

🌍 Manufacture & Compliance

• Country of Origin: United States (USA)
• Manufacturer: Woodward Governor Company
• Control Family: 2301A Load Sharing and Speed Control Series

⚡ Electrical & Operational Ratings

• DC Power Input: 18–40 VDC (24 VDC nominal)
• Speed Sensing Input: Magnetic Pickup (MPU) interface (100 Hz to 25 kHz)
• Actuator Output: 0–200 mA (proportional current output)
• Load Signal Interface: 0–3 VDC or 0–6 VDC (standardized inter-unit load share lines)
• Operating Temperature: -40°C to +75°C (-40°F to +167°F)

🚀 Application Fields

The 9907-173 is the backbone of small-to-medium industrial power systems:

• Generator Paralleling: Automatically balances real power (kW) across multiple generators on a common bus.
• Peak Shaving: Coordinates generator output with utility-supplied power to minimize demand charges.
• Isolated Grid Power: Maintains stable frequency and load balance in islanded (off-grid) microgrids.
• Marine Power: Ensures stable load distribution on shipboard service generators during varying port/sea operations.

📘 Product Instructions for Use

• Load Share Bus Calibration: When installing multiple units, ensure the Load Share bus signal is calibrated to the same voltage level at the controller terminals. Mismatched reference levels will cause one unit to “hog” the load while another runs light.
• MPU Noise Sensitivity: The 9907-173 relies on precise MPU frequency sensing. If the speed signal is noisy, the internal PID loop will become erratic. Ensure the cable shield is grounded at the control cabinet bus only.
• Potentiometer Adjustment: Adjustments should be made in small increments. Over-adjusting the “Gain” or “Reset” can lead to rapid oscillations in the fuel actuator linkage.

🌐 Governing Principles

The 9907-173 maintains stability through an integrated control logic architecture:

🔢 Step 1: Speed Control Loop

• The unit constantly compares the actual engine speed (via MPU frequency) to the desired setpoint. Any deviation is corrected by adjusting the actuator current.

🆔 Step 2: Load Sharing Logic

• The module monitors the load-share signal from other controllers on the bus. If the local load share signal differs from the bus average, the unit automatically biases the speed setting to increase or decrease fuel, effectively shifting the load until equilibrium is reached.

⚡ Step 3: Actuator Drive

• The resulting control output is a robust 0–200 mA signal that drives the internal coil of the hydraulic actuator, directly managing the engine’s fuel rack or throttle.

⚡ Power-On Commissioning Workflow

1. Supply Power Check: Verify the 24 VDC input power is within the 18–40 VDC specification.
2. Speed Latch Verification: Crank the engine and observe the controller; the “Speed Latch” state should engage once the MPU signal exceeds 1 VAC RMS.
3. Linkage Range Calibration: Use the “Load Limit” potentiometer to sweep the actuator. Ensure the mechanical linkage travels from full-closed to full-open without hitting physical stops.
4. Gain/Reset Tuning: Increase “Gain” until the engine response is prompt, then adjust “Reset” to remove any remaining steady-state speed droop or error.

📋 First-Time Running Checklist

• [ ] All field wiring is double-checked against the 9907-173 terminal diagram.
• [ ] Magnetic pickup air gap is adjusted to factory specs (0.5–1.0 mm).
• [ ] Load sharing signal lines are properly shielded and grounded at one point.
• [ ] Paralleling CTs are verified for correct polarity and phase.
• [ ] Backup mechanical overspeed safety is functional and tested independently.

❓ Q&A: Common Problems Explained

• Q: Why does the generator oscillate when paralleled with other units?
  • A: This is often caused by an incorrect “Load Gain” setting. If the gain is too high, the units will fight for load. Lower the Load Gain and ensure all units on the bus have the same reference voltage.
• Q: The governor outputs no current to the actuator. What is wrong?
  • A: This is a safety feature. If the controller does not detect a valid speed signal (from the MPU) or if the internal diagnostics detect a fault, it will cut current to the actuator to prevent an overspeed condition.
• Q: Is the 9907-173 compatible with 12VDC systems?
  • A: Always verify the specific tag on your unit. While many 2301A variants are 24V nominal, some are designed for specific supply ranges. Using the wrong voltage can damage the internal power supply board.

📦 Recommended Related Stock Models

1. Woodward 9907-018 (Alternative 2301A speed control)
2. Woodward 8273-501 (EPG Actuator Driver)
3. Woodward 9905-796 (DSLC Synchronizer)
4. Woodward 8440-2028 (easYgen-3200XT Controller)
5. Woodward 5464-662 (Distributed I/O Module)
6. Woodward 5466-425 (MicroNet Plus CPU)
7. Woodward 9907-167 (SPC Servo Controller)
8. Woodward 9907-838 (ProTech-G Safety System)
9. Woodward 5464-834 (Actuator Driver Module)
10. Woodward 8406-121 (EGCP-2 Generator Controller)