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Woodward 8915-791
Product Name: 3103 Series Electro-Hydraulic Servo Actuator (Integrated EM35 Driver, High Vibration-Industrial Version)
Product Introduction: The 8915-791 is a reinforced, vibration-resistant version of the 3103 actuator, developed for industrial steam turbines and steam valves in gas-turbine combined-cycle auxiliaries where vibration is severe. The electrical section is vibration-hardened and the hydraulic components are strengthened. With the integrated EM35 driver, it receives a 4–20 mA signal and uses the turbine lubricating oil source. It delivers high stability in the most vibration-demanding duty.
Detailed content
Technical Specifications:
- Control Input: 4–20 mA
- Medium: Turbine lubricating oil
- Supply Pressure: 0.24 – 1.1 MPa
- Rated Stroke: 38 mm
- Output Force: 11,200 N
- Power Supply: 24 Vdc
- Operating Temperature: –20 to +75 °C
- Protection Class: IP54
- Vibration Resistance: Complies with IEC 60068-2-6
Functional Features:
- Circuit boards and terminal blocks are vibration-hardened for high-vibration machine environments
- EM35 built-in adaptive PID control algorithm with excellent closed-loop dynamic performance
- LVDT position feedback closed-loop control
- Self-cleaning anti-contamination servo valve structure
- Fault spring reset – on loss of power or oil pressure the valve safely closes
- Status alarm output reporting servo valve faults and position deviation over-limit alarms
Application Scenarios: Steam turbine control valves in gas-steam combined-cycle units; blast-furnace gas drive turbines; speed-governing mechanisms for high-vibration industrial drive steam turbines.
Performance Parameters:
- Full-stroke response: ≤150 ms
- Positioning accuracy: ±0.25% FS
- Hysteresis: ≤0.5% FS
- Resolution: 0.1% FS
Material Composition: Cylinder barrel – cast steel; piston rod – thickened chrome-plated; servo valve spool – hardened stainless steel; terminal blocks – reinforced structure; seals – high-temperature-resistant fluorocarbon rubber.
Structural Features: Electrically hardened and locked driver box; enlarged foundation bolt specification connecting cylinder to base; servo valve with lock-wire anti-loosening design; LVDT with added anti-loosening clip; fully integrated monoblock structure.
Working Principle: The DCS output 4–20 mA control signal enters the EM35 driver board, which outputs current to drive the servo valve, distributing pressure oil to push the cylinder piston rod. The LVDT acquires the actual valve position for closed-loop regulation. Under fault conditions the spring forcibly closes the valve.
Installation Requirements: Piston rod preferred vertical downward, tilt not exceeding 15°, hanging is prohibited. The base must incorporate vibration-damping design to reduce transmission of machine vibration to the actuator body. The oil supply line shall be equipped with a 3 μm filter and a differential-pressure alarm. Signal cables shall be twisted-pair shielded with single-point grounding; power and signal cables shall be routed separately. Connect to the actuator oil ports only after pipeline flush-cleaning is qualified.
Usage Precautions: Regularly inspect the anti-loosening status of all bolts – vibrating conditions easily cause bolt loosening. Field disassembly and repair of the servo valve is prohibited. The piston rod surface must be protected from impact and scratches. Monitor oil particle count to ensure oil quality meets the standard. The electrical box must be protected from direct high-temperature steam impingement.
