Description

Woodward 9907-838 – 24 VDC PWM Load Sharing Module

Product Overview

The Woodward 9907-838 is a Load Sharing Module designed for generator-set applications using engines equipped with digital speed controls that accept a pulse-width-modulated (PWM) input. It provides both isochronous and droop load-sharing functions, allowing generator sets operating in parallel to distribute electrical load in a controlled manner. The unit operates from a 24 VDC supply and provides a Caterpillar-compatible PWM bias output. Woodward specifically identifies this version as having PWM output surge protection, distinguishing it from the earlier 9907-175.

Technical Specifications — 9907-838

Woodward’s product literature lists 9907-838 as the 24 VDC PWM version of the Load Sharing Module and identifies it as suitable for engines using compatible PWM speed-control inputs.

Woodward 9907-838

Key Features and Benefits — 9907-838

• 24 VDC operating supply
• PWM speed-control output
• Isochronous load sharing
• Droop load-sharing capability
• PWM output surge protection
• Designed for generator paralleling
• Compatible with selected Caterpillar digital speed controls
• Supports Woodward synchronizing and generator-loading accessories
• Suitable for legacy power-generation control systems

The load-sharing circuit compares generator loading and adjusts the speed-control bias so paralleled generator sets can share load appropriately. The module can also operate in droop mode when required for parallel operation with an infinite bus or another generator configuration.

Related Models

Woodward 9907-175: 24 VDC PWM Load Sharing Module with similar functionality but without PWM output surge protection.

Woodward 9907-252: 24 VDC Load Sharing Module using a 0.5–4.5 VDC analog speed-reference output.

Woodward 9907-173: 115/230 VAC Load Sharing Module using a ±3 VDC analog output.

Woodward SPM-A: Synchronizer commonly used with compatible generator paralleling and load-sharing systems.

Installation and Maintenance — 9907-838

Before installation, verify the 24 VDC supply, generator CT/PT connections, PWM input requirements of the connected speed controller, load-sharing wiring, and droop configuration. CT polarity and phase identification should be checked carefully because incorrect power-sensing connections can produce erroneous load measurements.

Use shielded wiring for load-sharing signals and follow the grounding arrangement specified by Woodward. After installation, verify generator load indication, PWM output, load-sharing response, and droop/isochronous operation under controlled conditions.

Personally, I would confirm the receiving speed controller first. The PWM interface is the critical compatibility point; an analog-output load-sharing module is not a direct substitute simply because its generator application is similar.

Product Warranty — 9907-838

Warranty coverage depends on the supplier, equipment condition, and purchase agreement. For new-old-stock, surplus, or refurbished inventory, confirm the exact part number, hardware condition, functional-test results, and warranty period before purchase.

The Woodward 9907-838 should be treated as an exact PWM load-sharing spare. Its 24 VDC supply, PWM interface, surge protection, and generator-control configuration should all be verified against the existing system before commissioning. Woodward continues to list this part number within its Load Sharing Module product documentation.