Overview

The 9905-002 is a high-voltage powered governor module from the Woodward 2301A control family, developed for engine-driven generator applications. Unlike low-voltage variants, the 9905-002 operates directly from AC or high-level DC sources, making it suitable for installations where 24 VDC is not available.

This unit continuously interprets speed signals from a magnetic pickup and adjusts actuator current output to regulate fuel delivery. It ensures stable frequency control and coordinated load distribution across parallel generator systems.

Technical Specifications

Functional Description

The 9905-002 acts as the central control element in an electronic governing system. It compares actual engine speed against a reference setpoint and dynamically adjusts actuator output to maintain the desired operating condition.

Its control strategy is based on a PID loop, enabling stable performance even under rapid load fluctuations.

Key Features

Flexible Operating Modes

Supports both isochronous and droop configurations. Isochronous mode maintains constant speed regardless of load changes, while droop mode enables controlled frequency variation for parallel generator operation.

Integrated Load Sharing Capability

Includes dedicated load-sharing interfaces that allow multiple controllers to exchange load signals. This ensures balanced kW distribution across generators and prevents uneven loading conditions.

Remote Speed Adjustment

Provides an input for an external potentiometer, allowing operators to fine-tune engine speed from a control panel without direct access to the module.

Stable Actuator Drive Output

The 0–200 mA analog output is optimized for Woodward actuators, delivering precise and consistent fuel control across different engine types.

Control Tuning and Dynamics

The controller allows manual adjustment of dynamic response parameters:

• Gain: Defines proportional sensitivity to speed deviations

• Reset: Eliminates steady-state offset through integral action

• Actuator Compensation: Matches output behavior to actuator response characteristics

These parameters enable fine tuning for various engine sizes and fuel systems, minimizing oscillation and improving stability.

Application Areas

The 9905-002 is commonly deployed in:

• Diesel and gas generator sets

• Industrial turbine auxiliary systems

• Power plant control panels

• Retrofit projects replacing mechanical or legacy governors

It is particularly useful in facilities where higher voltage supplies are standard.

Comparison with 9905-211

Although both belong to the same 2301A platform, their power requirements differ:

• 9905-002: High-voltage AC/DC input

• 9905-211: Low-voltage 24 VDC input

Performance and control capabilities remain consistent across both models, with selection driven by available power infrastructure.

FAQ

What type of sensor is required for speed input?

A magnetic pickup sensor is required, providing a frequency signal proportional to shaft rotation.

Can this unit control multiple generators in parallel?

Yes, when connected through load-sharing lines, it enables coordinated load distribution across multiple units.

Is it suitable for retrofit applications?

Yes, it is widely used to upgrade older governing systems to modern electronic control.

What safety precautions are required?

Due to high-voltage operation, proper grounding is mandatory. Always isolate power before performing wiring or configuration changes.