© 2019 HV Coil LLC. All rights reserved.

700 Newport Street

Newcomerstown, Ohio 43832

(P) 330-556-4395

(F) 330-863-8892

info@hvcoilusa.com

HV Coil LLC - High Voltage Roebeled Stator Bar and Coil Manufacturing 

The HV Coil Difference

Our proprietary manufacturing process yields a world class stator winding

  1. A coil geometric design that ensures sufficient winding clearances and the prevention of surface discharge (PD).

  2. Superior manufacturing quality control yielding repeatable end winding shape and lead position.

  3.  An industry proven insulation system utilizing 100% tape-applied components (Mica Groundwall Insulation, OCP - Outer Corona Protection / Bar Armor and Voltage Supressor).

  4. Rewind kits inclusive of precision assembly tools and componenet materials designed for longevity.....not lowest cost.

Quality

Stator winding quality and longevity is achieved by addressing key points in three main categories.  Most failure modes can be attributed to a breakdown within these categories:

  1.  Coil / Bar Design

    • Surface / Partial Discharge (PD) will occur due to inadequate conductor spacing within the endwinding.

    • Catastrophic coil-to-ground failures can occur if the coil winding design violates the minimum required distance from ground.

    • Inadequate coil blocking along endwinding, within the phase connections or connection buswork, or at the series loop causing excessive end winding vibration and dusting.

  2.  Coil / Bar Manufacturing

    • PD activity due to inadequate bonding of mica groundwall insulation to the Outside Corona Protection (OCP) or Bar Armor causing accelerated degredation within the core section of the generator.

    • PD due to inadequate bonding & cure (or poor workmanship during application) at the voltage gradient and OCP interface

    • PD due to inadequate manufacturing quality control yielding bar-to-bar endarm spacing that is inconsistent, and in extreme cases contacting one another.

  3.  Coil / Bar Installation

    • Inadequate coil winding restraint due to substandard materials or work practices causing end winding vibration and dusting.

    • Lack of necessary alignment & assembly tools required to ensure each coil is properly placed and tied in the winding.

 Poor bonding at voltage suppressor / OCP interface - degradation penetrates several layers of mica insulation.

Inadequate spacing within endwinding.  Severe PD activity along coil endarms at phase breaks.

Inconsistent endwinding spacing.  Indicative of excessive manufacturing and installation variance.

Poor shape control causing PD at contact point between bars.

 Poor coil endarm shape control causing convergence of end winding, misaligned series connections, PD at phase breaks and inadequate blocking causing vibration and dusting.

Phase Connections

New winding is connected to re-insulated connection rings.