Woodward 9905-711

Woodward 9905-711

Product Introduction
The Woodward 9905-711 is an advanced digital synchronizer and load control module. It is designed to automate the complex process of matching a generator to a live bus and then seamlessly transferring load, replacing older analog synchronizing systems with precise digital control.

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Description

Woodward 9905-711

Technical Specifications

  • Product Type: Digital Synchronizer and Load Controller.
  • Inputs: Generator and Bus VT/PT signals, frequency, and voltage.
  • Outputs: Raise/Lower speed and voltage contacts, breaker close command.
  • Communication: RS-232/485 or Modbus for monitoring.

Functional Features

  • Automatic Synchronization: Automatically adjusts generator speed and voltage to match the bus within preset windows.
  • Closed-Loop Load Transfer: Smoothly transfers load from the grid to the generator (or vice versa) without transients.
  • Programmable Parameters: All setpoints (phase window, voltage window, ramp rates) are software-configurable.
  • Self-Monitoring: Continuously checks VT/PT circuits and internal health.

Application Scenarios
Used in generator control panels, automatic transfer switches (ATS), and microgrid controllers for safe and automated paralleling.

Performance Parameters

  • Sync Accuracy: Phase match within ±1-2 degrees, voltage match within ±1%.
  • Close Timing: Calculates breaker close time to achieve zero-phase-angle closure.
  • Load Transfer Rate: Adjustable kW/sec ramp rates for smooth transitions.

Material Composition
Industrial-grade digital electronics in a rugged enclosure. Front panel includes a display and keypad for local configuration and monitoring.

Structural Characteristics
DIN-rail or panel-mount form factor. Features screw terminals for power, VT/PT inputs, and relay outputs. LED indicators show sync status, close permissive, and faults.

Working Principle
Samples the generator and bus waveforms to calculate phase angle difference, frequency difference, and voltage difference. When all parameters are within the programmable windows, it calculates the breaker close time and issues the close command at the precise moment to achieve zero-phase-angle closure.

Installation Requirements
Connect VT/PT signals with proper fusing. Wire raise/lower outputs to the governor and AVR. Configure all parameters via the front panel or software before commissioning.

Usage Precautions

  • Verify VT/PT polarity and phase rotation before enabling auto-sync.
  • Start with wide sync windows and narrow them after successful testing.
  • Always have a manual synchronizing method as a backup.

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