WOODWARD 5441-693 Digital Servo Drive / Actuator Control Module

Description

1. Core Overview & Positioning

2. Key Features & Functions

• Closed-Loop Position Control:​ Continuously compares the position command​ from the primary controller (e.g., 723PLUS) with the actual position feedback​ from an LVDT/RVDT sensor and adjusts its output to eliminate any error.
• Flexible I/O:​ Typically accepts a variety of command signals (e.g., ±10V DC, 4-20mA, digital) and provides a high-current output suitable for driving inductive servo valve coils.
• Advanced Integrated Control:​ Contains sophisticated control algorithms (PID with advanced compensation) optimized for demanding actuator dynamics.
• Comprehensive Diagnostics & Protection:
  • LVDT/RVDT Monitoring:​ Detects sensor faults (open circuit, short circuit, loss of excitation).
  • Actuator/Driver Fault Detection:​ Monitors for coil faults, over-current, excessive position deviation, and communication loss.
  • Fail-Safe Behavior:​ Can be configured to drive the actuator to a predefined safe position upon a fault.
• Field Configurability & Tuning:​ All operating parameters—input/output scaling, servo loop gains (P, I, D, feedforward), current limits, and fault settings—are configured and tuned via software (Woodward Toolkit) to match the specific actuator and application.
• Communication:​ Equipped with communication ports (often a proprietary Woodward bus like Gov. Bus​ or NetBus) for integration with the primary controller, configuration, and real-time diagnostics.

3. Common Technical Specifications

• Part Number Context:​ The -693suffix defines the specific variant, indicating its firmware version, connector types, and possibly its default calibration or application focus.
• Command Input:​ Configurable for analog (±10V DC, 4-20mA) or digital (synchronous serial) input.
• Feedback Input:​ Designed for AC LVDT/RVDT sensors (standard excitation: e.g., 3 Vrms @ 2.5 kHz or 5 Vrms @ 5 kHz).
• Output Drive:​ Current output stage capable of driving typical servo valve coils (e.g., 0 to ±200 mA range).
• Power Supply:​ Requires external DC power supplies, typically ±15V DC for control electronics and a separate +24V to +80V DC for the high-side output stage.
• Physical Form:​ A printed circuit board assembly designed for mounting in a dedicated chassis or control cabinet, often with robust connectors for power, signals, and communication.

4. System Integration & Configuration

• System Role:​ It is the «muscle»​ in the control loop, directly interfacing with the actuator. The primary governor (e.g., 723) is the «brain»​ calculating the setpoint.
• Configuration Software:​ Exclusively configured using Woodward Toolkit​ software. The setup process includes:
  1. Defining input/output signal types and scaling.
  2. Performing an LVDT calibration​ to map the sensor’s electrical output to the actuator’s physical stroke.
  3. Servo Tuning:​ Adjusting PID gains and other dynamic compensation to achieve fast, stable, and oscillation-free response.
• Critical Calibration:​ Mechanical calibration (linking the LVDT core to the actuator rod) is a precise, mandatory step for accurate control.

5. Typical Applications

• Aeroderivative & Heavy-Duty Gas Turbines:​ Controlling fuel metering valves for acceleration, deceleration, and load control.
• Steam Turbines:​ Positioning governor valves and intercept valves.
• Diesel & Dual-Fuel Engines:​ Governing fuel injection actuators for speed and load regulation.
• Compressor Control:​ Driving anti-surge valves and performance control valves.