VariStroke II Servo

Servovalve (V90V-R)

The new industry standard electro-hydraulic linear actuator used in the most demanding environments providing superb accuracy and resolution for stable, reliable and safe operation of steam turbine control valves or valve racks. Used on mechanical-drive or generator-drive steam turbines, the robust design with 50 lbf chip shear force, and self-cleaning port design uses a low-pressure hydraulic oil source (typically turbine lube oil) for output shaft force. The V90V-R is a remote double acting fail-retract servovalve used to drive a Woodward or OEM power cylinder for steam and hydro turbines.
Product Type

About 9907-1288

Turbine Actuator

  • Application Notes
  • Brochure
  • Product Specification
  • Software Manual
  • Technical Manual
  • Software
Varistroke II servovalves solves steam turbine users #1 reliability problem...dirty oil!
The patented dirt tolerant and self-cleaning technology of Woodward's VariStroke servovalve ensure greater overall reliability of your steam turbine. The VariStroke line of linear electro-hydraulic valve servovalves operate mechanical-drive or generator-drive steam turbines. These servovalves utilize a low-pressure, hydraulic oil source (typically turbine lube oil) to provide output to a cylinder shaft. Their superb accuracy and resolution make them ideal for steam valve control and related turbine speed and load control, where turbine up-time and availability is essential.
The VariStroke line is configurable via a simple user-friendly, computer-based PC service tool, allowing users to easily configure, calibrate, and adjust all internal functions and response settings. Its integrated driver includes a 4-20 mA output channel to indicate output shaft (control valve) position, as well as unit alarm and shutdown relay outputs for use as unit health and status indications. The 4-20 mA demand inputs and dual-redundant shaft position sensors allow it to continue to operate even with demand input or feedback sensor failures, ensuring extended run-times between forced outages and on-line system repair.
The total installed cost for this servovalve is low because it is completely assembled and tested at the factory, greatly reducing OEM and end-user fabrication, testing, and site assembly time. In retrofit applications, the VariStroke servovalve can be used to directly replace the existing servo system. This saves costly repairs to existing and aging servos, eliminates the difficulty of obtaining spare parts for obsolete equipment, and reduces calibration time and difficulty.
Dirt-tolerant design:
  • Two moving parts
  • 105 lb chip shear force
  • Self-cleaning valve design
Variable / configurable shaft stroke lengths
Fast slew rates/times:
Up to 10 inches/second (254 mm/s)
Precise position control
Integrated driver:
  • 4–20 mA or CAN open
  • Included valve flow linearization table
  • Redundant CANopen network communications
  • Redundant LVDT position sensor available
  • Certified for Hazardous Locations 

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