Description
The Woodward 9907-838 is a high-performance Load Sharing Module (LSM) engineered for industrial generator systems. Its primary function is to manage and distribute electrical loads proportionally among multiple parallel-connected generators. Specifically designed for use with Caterpillar engines equipped with digital speed controls and Pulse Width Modulated (PWM) inputs, this module acts as an interface that allows Caterpillar engines to work seamlessly with Woodward power generation accessories and other Woodward-controlled engines.
WOODWARD 9907-838
Technical Specifications (Datasheet Summary)
The 9907-838 module provides deterministic, real-time control to ensure system frequency and voltage stability during varying load conditions.
| Parameter | Specification |
| Model Number | 9907-838 (Replaces obsolete 9907-175) |
| Power Supply | 18–32 VDC (Standard 24 VDC) |
| Power Consumption | Approximately 10 W |
| 3-Phase PT Inputs | 95–130 VAC |
| Load Sharing Types | Isochronous and Droop |
| Output to Speed Control | PWM (Pulse Width Modulated) or Analog (+0.5 to +4.5 VDC) |
| Full Load Condition | 3 to 7 Arms |
| Operating Temperature | -40°C to +70°C (-40°F to +158°F) |
| Shock Resistance | 40 G, 11 ms sawtooth pulse |
| Weight | Approximately 1.36 kg (3 lbs) |
Key Functional Features
- Isochronous Load Sharing: Maintains a constant system frequency regardless of the load, perfectly balancing the power output between paralleled generators.
- Droop Load Sharing: Allows for a reduction in frequency as the load increases, which is essential for stable operation when paralleled with an infinite bus (utility grid) or other droop-controlled units.
- Caterpillar Integration: Features a specialized PWM output specifically designed to communicate with Caterpillar’s digital engine governors.
- Synchronizer Compatibility: Fully compatible with the Woodward SPM-A Synchronizer to automate the paralleling process.
WOODWARD 9907-838
Application Areas
The Woodward 9907-838 is a standard choice for mission-critical power applications where reliability is paramount:
- Remote Power Stations: Managing micro-grids where multiple small-to-medium generators must work in unison.
- Marine Propulsion & Power: Balancing the electrical load on ships and offshore platforms.
- Data Centers: Ensuring seamless load transfer and stability in emergency backup power systems.
- Industrial Facilities: Parallel operation of standby generators with the utility grid to manage peak shaving or emergency power requirements.
Country of Origin
The Woodward 9907-838 is primarily manufactured in the USA. Some specialized variants may be produced in other Woodward global facilities (such as Taiwan), but the design and core engineering are based on American industrial standards.
Product Usage Instructions
1. Installation and Mounting
- Environment: Install the module in a location free from excessive dust, moisture, and high-frequency vibration.
- Orientation: It should be mounted within a control cabinet, typically on a sub-panel. Ensure there is enough space for airflow to maintain the operating temperature limits.
- Cabling: Use shielded twisted-pair cables for all low-level signal and PWM lines. The shield should be grounded only at the Load Sharing Module end to prevent ground loops.
2. Configuration and Calibration
- PT Connections: Connect the 3-phase Potential Transformer (PT) inputs to the generator bus. Ensure the phase sequence is correct to allow the module to calculate power accurately.
- Droop Setting: If operating in droop mode, use the onboard potentiometer to adjust the percentage of droop (typically 3% to 5%) required for system stability.
- Load Balance: During commissioning, use the “Load Gain” adjustment to ensure all parallel units contribute an equal percentage of their rated power to the total load.
3. Maintenance
- Visual Inspection: Regularly check for loose terminal screws and signs of heat discoloration on the connectors.
- Signal Verification: Periodically verify the DC power supply voltage is within the 18–32 VDC range to ensure the internal RISC processor operates without reset cycles.
Recommended Related Woodward Products
If you are designing or maintaining a system involving the 9907-838, the following Woodward components are often used in the same architecture:
- Woodward 2301A (9907-018): A speed control and load sharing module used for older analog engine systems.
- Woodward SPM-A (9907-028): A synchronizer used to automatically bring the generator into phase with the bus before closing the breaker.
- Woodward 2301E (8273-1012): The modern digital successor to the 2301A, often paired with LSMs for integrated control.
- Woodward 9907-173: A load sharing module variant that accepts high-voltage AC input (110–240 VAC).
- Woodward 723PLUS: A versatile digital control platform used for more complex engine management tasks.
