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Woodward 9902-408
Product Name: Variable Stator Vane (VSV) Actuator
Product Introduction: The 9902-408 is a Woodward Variable Stator Vane (VSV) actuator for gas turbine applications. It is part of the 3055 VSV Actuator product line and works in conjunction with 9902-407 to provide closed-loop position control of VSV actuators on industrial gas turbines. The actuator output shaft attaches to the variable stator vane hardware, enabling precise vane positioning under electronic control.
Detailed content
Technical Specifications:
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Product Type: Variable Stator Vane (VSV) Actuator
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Model Designation: 9902-408 (paired with 9902-407)
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Actuator Output Travel: Up to 3.445 inches (87.50 mm)
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Position Feedback: Integral LVDT providing electrical signal proportional to output position
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EU Compliance: Compliant with Directive 2006/42/EC as partly completed machinery
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ATEX Marking: Ex II 3 G, Ex nA IIC T4X Gc
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Applicable Standards: EN60079-0:2012/A11:2013, EN60079-15:2010
Functional Features:
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Closed-loop position control of VSV actuators
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Integral LVDT for precise position feedback
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Aluminum case with through-hardened stainless steel internal parts
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Hydraulic operation with ports marked “ROD” and “HEAD”
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Optional accumulator port (“ACC”) for fail-safe operation during pump failure
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Explosive atmosphere certified (Ex II 3 G)
Application Scenarios: Industrial gas turbine variable stator vane positioning for surge control and part-load efficiency optimization.
Structure & Materials: The actuator features an aluminum case with through-hardened stainless steel internal parts. A Linear Variable Differential Transformer (LVDT) is an integral part of the actuator.
Working Principle: A hydraulic pump supplies pressure to the servovalve. The electronic package sends a command to the dual servovalve, which directs hydraulic flow to the “ROD” or “HEAD” port of the actuator. The piston moves, rotating the VSV vanes. The integral LVDT feeds position back to the final driver, closing the control loop. An optional accumulator connected to the “ACC” port provides enough pressurized oil to move the actuator to the commanded position should the hydraulic pump fail.
Installation Requirements: Install per Woodward 3055 VSV Actuator manual (publication 26213). Lifting strap and hoist required for handling. Align serrated drive shaft of tachometer pump correctly for unencumbered rotation. Hydraulic ports “ROD” and “HEAD” connect to corresponding servovalve ports.
Usage Notes: Equipment must not be put into service until the final machinery is declared in conformity with Directive 2006/42/EC. Wear appropriate PPE. Follow ESD awareness procedures when handling electronic components.
