Woodward 9908-273

Woodward 9908-273

Product Introduction
The Woodward 9908-273 is a specialized digital interface module designed to provide precise control and monitoring of electro-hydraulic or electric actuators. It serves as the critical link between the turbine controller and the final control element, ensuring accurate valve positioning and reliable fail-safe operation.

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Description

Woodward 9908-273

Technical Specifications

  • Output Type: High-current analog output for actuator drive.
  • Feedback Input: Accepts LVDT or potentiometer feedback for closed-loop positioning.
  • Control Signal: Receives position command from the main turbine controller.
  • Power Supply: Regulated DC supply with over-current protection.

Functional Features

  • Closed-Loop Positioning: Continuously compares command and feedback signals to achieve exact valve positioning.
  • Fail-Safe Logic: Drives the actuator to a pre-programmed safe position upon loss of power, signal, or communication.
  • Diagnostics: Monitors actuator health, including feedback wire breaks, over-travel, and excessive response time.
  • Signal Isolation: Galvanic isolation protects the controller from actuator-induced electrical noise.

Application Scenarios
Used in steam turbine inlet and extraction valve control, gas turbine fuel valve actuation, and engine fuel rack positioning.

Performance Parameters

  • Positioning Accuracy: Better than ±0.25% of full stroke.
  • Response Time: Fast dynamic response for excellent transient performance.
  • Drive Capacity: Sufficient current output for high-inertia actuators.

Material Composition
Industrial-grade electronics in a protective metal chassis with gold-plated terminals for reliable connections.

Structural Characteristics

  • Mounting: Panel or DIN rail mount.
  • Indicators: LEDs for power, command, feedback, and fault status.
  • Wiring: Screw terminals for field connections.

Working Principle
The module receives a position command from the controller and outputs a proportional drive signal to the actuator. It simultaneously reads the actuator’s position feedback and adjusts the output to eliminate any position error. If a fault is detected, the module overrides the command and drives the actuator to the fail-safe position.

Installation Requirements

  • Install in a clean, dry control panel.
  • Use properly sized conductors for actuator power connections.
  • Ensure the feedback linkage is mechanically secure and free of backlash.

Usage Precautions

  • Verify the fail-safe position matches the mechanical safety requirements of the prime mover.
  • Do not bypass internal protection circuits.
  • Perform regular stroke tests to verify calibration and response.

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