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Capabilities & Process

HV Coil has over 125 years of collective experience designing and manufacturing high voltage Turbo and Hydro bar (half-coil) stator windings and associated components.  Our proprietary manufacturing process enables us to offer superior replacement windings that will:

  1. Fit and nest perfectly within the stator core and end winding support structure

  2. Provide long term trouble free operation

  3. Outperform the original winding by operating at higher efficiencies and generating capacities

Data Acquisition

HV Coil's proprietary manufacturing process is designed to work seamlessly with data obtained in two ways:

  1.  Onsite measurement outage to obtain the generators fundamental electrical and physical attributes

  2.  OEM supplied drawings or 3D geometry in virtually any format


Every new winding is designed to ensure:

  1. Total loss reduction by maximizing copper content and optimizing roebel transpositions

  2. Optimized series connections (stranded / consolidated / hybrid configurations)

  3. Optimized end winding design to maximize system service life by:    (learn more here)

    • Incorporating consistent and adequate clearances to prevent partial discharge between components

    • Using materials and design practices to minimize in-service vibration and thermal expansion stresses


Manufacturing & Quality

HV Coil's manufacturing process utilizes modern automated manufacturing equipment to process an industry proven class F resin rich insulation system.  This system demonstrates industry leading dielectric properties, mechanical strength, long term thermal stability and reliability.   The processing of our system requires no EPA permits, making HV Coil a safe and environmentally friendly manufacturing facility.


To ensure perfect form/fit/function, HV Coil performs the following in-process quality checks on every stator winding.

  1.  Full-scale mock stator inspection validates:

    • Circumferential and radial position of series loop connections

    • Sufficient crossover clearance between top and bottom bar sets at core exit

    • Agreement between measured bar-to-bar end winding clearances and design requirements

  2. 100% production bar electrical testing

    • 220 VAC strand isolation tests after flat bar consolidation

    • AC Hipot per IEEE Std. 4

    • Surge testing for multi-turn bars per IEEE 522

    • Power Factor per IEEE 286 with Tan Delta < 1%

    • Customer specific testing availble upon request


In addition to stator winding manufacturing, HV Coil manufactures all associated connection rings / connection hardware and will provide the entire rewind kit (wedges/SRS/TRS/RTD's/fillers/paints/resins/felts/tie materials...etc).

3D Representation of new Stator Winding Design

Bar Armor Application


HV Coil offers expedited delivery schedules.  Contact us for details.

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