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Woodward 8915-418
Product Name: AC Linear Variable Differential Transformer (AC LVDT) Position Sensor
Product Introduction: 8915-418 is an AC LVDT (Linear Variable Differential Transformer) sensor that provides high-precision displacement detection for valves, actuators, and other moving components. It is widely used in gas turbine fuel control, servo valve feedback, and industrial automation.
Detailed content
Technical Specifications:
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Sensor type: AC Linear Variable Differential Transformer (AC LVDT)
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Corresponding model: HLR-750-6000 series specific configuration
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Housing diameter: 0.750 inch (19 mm)
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Stroke range: 6 inches (based on series code 6000)
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Linearity error: ≤ ±0.15% FSO (typical), ≤ ±0.25% FSO (maximum)
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Null voltage: 0.5% FSO
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Repeatability: 0.01% FSO
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Hysteresis: 0.01% FSO
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Operating temperature: -54°C to +135°C (standard), -54°C to +204°C (high-temperature variant)
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Thermal coefficient: < -0.02% / °C FSO
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Humidity tolerance: 90% relative humidity
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Expected life: Exceeds 100 million operating cycles
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Shock rating: 1000 g, 11 ms
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Vibration rating: 20 g to 2 kHz
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Lead wire: 28 AWG Teflon-insulated wire, standard length 305 mm
Functional Features:
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Non-contact measurement principle; no friction, no wear, theoretically infinite service life
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Free core design for easy coupling with external mechanical components
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Epoxy-potted coil windings for excellent shock and vibration resistance
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Full stainless steel sealed housing, protection rating IP61 to IP68
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Standardized electrical interface compatible with mainstream LVDT signal conditioners
Application Scenarios:
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Gas turbine valve position feedback
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Hydraulic and pneumatic actuator stroke monitoring
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Fuel control system linear displacement detection
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High-precision positioning in industrial process automation
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Flow control feedback loops in energy sector
Material Composition:
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Housing: Full stainless steel monolithic structure with corrosion and oxidation resistance
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Coil bobbin and windings: High-temperature insulating material with epoxy potting protection
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Core: High-permeability alloy with surface treatment to reduce wear
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Lead wire: 28 AWG Teflon insulation
Structural Characteristics:
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Compact 19 mm diameter design for space-constrained applications
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Free core structure allows connection to target mechanical components via extension rod
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Sealed design prevents ingress of moisture, dust, and chemical contaminants
Working Principle: The primary coil is energized with AC excitation voltage, inducing voltages in two symmetrically arranged secondary coils. As the core moves within the coil assembly, the induced voltages in the two secondary coils change differentially. By measuring the ratio of the difference to the sum of the two secondary output voltages, a precise electrical signal proportional to core displacement is obtained. Since there is no physical contact between core and coil, the sensor experiences no mechanical wear.
Installation Requirements:
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Ensure proper alignment between the sensor core and the measured moving component
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Use appropriate extension rods for coupling the free core to target mechanisms
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Maintain lead wire routing away from high-electrical-noise sources
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Provide strain relief for the 28 AWG lead wire
Usage Notes:
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Operate within specified temperature and vibration limits
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Do not exceed the rated shock load to avoid permanent calibration shift
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Verify linearity and null voltage during periodic maintenance
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Protect the Teflon-insulated leads from mechanical abrasion and excessive heat
