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Woodward 8921-020
Product Identification: EHPC (Electro-Hydraulic Power Cylinder) — custom, application-specific linear integrating actuator, sister unit to 8921-018 within the EHPC family.
Product Overview: The 8921-020 is Woodward’s EHPC designed for steam turbine control valve or valve rack positioning. Like all EHPC units, it is configured and manufactured for a specific application, using a low-pressure hydraulic oil source amplified through three stages to produce the required output shaft force.
Detailed content
Working Principle: Accepts a 0–200 mA integrating input signal and converts it to precise linear shaft motion via three-stage hydraulic amplification of an 80–250 psi supply.
Technical Specifications: (EHPC family baseline)
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Supply Pressure: 80 to 250 psi (552 to 1724 kPa)
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Input Power: 24 Vdc ±10% @ 2 A
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Input Signal: 0–200 mA integrating input signal (100 mA null)
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Position Feedback: 4–20 mA, 20–4 mA, 0–10 Vdc, or 10–0 Vdc
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Output Shaft Diameter: 1.750 in (44.45 mm)
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Shaft Material: Hardened 17-4 PH stainless steel
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Thread Size: 1.250 in –12 UNF-2A
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Pressure Sensitivity: Not less than 2%
Application Scenarios: Steam turbine control valves, valve rack positioning.
Installation Requirements:
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Rigid mechanical mounting to valve assembly
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Filtered hydraulic supply regulated to 80–250 psi
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24 Vdc ±10% power at 2 A
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ESD-safe electrical connections
Usage Precautions: Same ESD handling and safety precautions as 8921-018. Independent overspeed protection mandatory for the prime mover.
