Woodward 8516 Series Turbine Actuators 8516-085

Technical Dossier

Product Details And Specifications

Woodward 8516 Series Technical Notes

The Evolution of 8516 Architecture

The 8516 series was introduced as a successor to earlier Woodward hydraulic amplifier designs, transitioning from purely mechanical feedback to electronic position control loops. Early variants (circa 1978–1990) used analog signal processing with discrete op-amp circuits and required periodic potentiometer calibration. Mid-generation units (1990–2005) incorporated improved EMI shielding and extended the operating temperature range to accommodate tropical and arctic installation environments. Later revisions introduced LVDT (Linear Variable Differential Transformer) position feedback as standard, replacing older resistive feedback mechanisms that were prone to wear-induced drift.

Compatibility across generations is a known engineering challenge. Early 8516 units used a 4–20 mA input standard, while some transitional models accepted 0–200 mA signals from legacy Woodward EG governors. Technicians sourcing replacement units must verify the input signal type, supply voltage (typically 18–40 VDC or 90–132 VAC depending on variant), and actuator stroke length before substitution. The series entered the mature/end-of-production phase approximately 2010–2015, with Woodward's ProAct and TM series designated as functional successors. However, direct mechanical and electrical interchangeability with ProAct units is not guaranteed without site-specific engineering review.

8516 Series Full Catalog & Functionalities (SKU List)

The following SKUs represent verified models within the Woodward 8516 actuator series. Each unit is classified by its primary application and output torque class:

8516-009: Low-torque electric actuator, 9 in-lb output, 4–20 mA input, for small steam valve applications.
8516-025: 25 in-lb output actuator, single-phase AC supply, used on auxiliary turbine governors.
8516-038: 38 in-lb output, extended stroke variant, compatible with Woodward 505 governor systems.
8516-050: 50 in-lb mid-range actuator, dual-coil design, suitable for gas turbine fuel valve control.
8516-060: 60 in-lb output, LVDT position feedback standard, 18–40 VDC supply.
8516-070: 70 in-lb output, high-cycle-rate variant, designed for load-sharing applications on parallel turbine sets.
8516-075: 75 in-lb output, tropical-rated enclosure (IP55), used in offshore and high-humidity environments.
8516-085: 85 in-lb output electric actuator, 4–20 mA command input, LVDT feedback, 18–40 VDC; standard replacement unit for mid-size industrial steam turbine governors.
8516-088: 88 in-lb output, modified spring return mechanism, used where fail-closed valve action is required.
8516-090: 90 in-lb output, high-resolution position control, compatible with MicroNet TMR governor platforms.
8516-100: 100 in-lb output, heavy-duty variant, rated for continuous-duty cycling in base-load power generation.
8516-115: 115 in-lb output, extended temperature range (−40°C to +85°C), used in arctic and cold-climate installations.
8516-120: 120 in-lb output, dual-redundant position feedback, for safety-critical turbine trip applications.
8516-130: 130 in-lb output, high-force variant for large steam admission valve control on utility-scale turbines.
8516-150: 150 in-lb output, maximum-torque model in the 8516 range, used on large hydro turbine wicket gate actuators.

Quality Control for the 8516 Series Range

Each 8516 series unit processed by DriveKNMS undergoes a structured test protocol prior to dispatch. Electrical testing includes supply voltage tolerance verification across the rated input range, coil resistance measurement, and insulation resistance testing at 500 VDC. Functional testing applies a calibrated 4–20 mA signal sweep and measures actuator shaft position response against the manufacturer's stroke specification. LVDT output linearity is verified using a calibrated signal analyzer. Units with analog feedback mechanisms are bench-calibrated using Woodward's published calibration procedure. Hydraulic variants undergo pressure-hold and leak-down testing at rated working pressure. All test results are documented and accompany each unit shipment. Units that do not meet specification are either repaired to tolerance or classified as non-functional and excluded from inventory.