The #1 US-owned power transformer manufacturer in North America Core type transformers up to 500 MVA, 525kV Shortest lead time in the industry Shell type power transformers up to 1400MVA 500kV The most reliable transformers made right here in the USA


Since 1983 Virginia Transformer Corp (VTC) has offered a superior encapsulated dry type transformer that withstands the toughest environments. We call it UNIClad®. Our customers know it as the system that offers unmatched design integrity and strength compared to traditional cast coil products. UNIClad® is simply the best choice for your applications with high humidity, contaminated conditions, short-circuit loading and impact loading. And you’ll spend less for UNIClad® than a conventional unit because we design exactly the transformer you need. With VTC, you never have to overbuy simply because what you need isn’t standard.VTC unveiled UNIClad® in the early 1980s to address the growing need for a product that could outperform traditional systems. Standard cast coil construction can withstand short-circuit forces, but its brittle epoxy construction is prone to cracking from thermal, mechanical and electrical forces. This cracking allows moisture and corrosion to attack the coil causing failure. Our UNIClad® coils withstand thermal cycling forces, short-circuit shock and operating vibration without cracking, thanks to our unique encapsulation and sealing process. We completely seal UNIClad® coils with a 220° C-rated, flexible polyester varnish applied under vacuum and pressure. This tough, flexible cladding material is also highly chemical and moisture resistant. Besides our vacuum sealing process, VTC uses NOMEX on UNIClad® coils to ensure flexibility of the insulation system and the highest thermal rating for the longest life. UNIClad® can even withstand total water immersion for 24 hours with no change in seal integrity.



By filling the coils with low-viscosity 100% solid polyester varnish under vacuum and pressure, VTC also assures void-free coils. UNIClad® coils exhibit very low partial discharge levels, which means longer life, a reduction in the possibility of internal dielectric failure, and partial discharge-free operations maintained for the life of the transformer. We seal coil ends using an evacuated resin system formulated to match the coefficient of thermal expansion of the coil.UNIClad® 220°C insulation system and 115°C temperature rise design provides a continuous overload capability of approximately 15%. Even under overload conditions, UNIClad® will maintain temperatures within the insulation rating. The solid filling of our coils improves thermal conductivity, allowing the coils to run cooler and resulting in longer unit life. On average, the life expectancy of a UNIClad® is 40 years at a constant rated load, subject to proper application, protection, maintenance and duty cycle.


VTC custom designs all UNIClad® units, resulting in significant dollar savings to you. We simply don’t believe in forcing customers to choose from pre-determined molds, designs, or specifications. Such on-size-fits-all product offerings often force customers to “size-up” their unit, wasting money and taking up extra space at their site. With UNIClad®, you’ll pay only for what you need. And you can expect delivery of your UNIClad® system in about half the time needed for standard cast coil units thanks to our commitment to global sourcing.


  • Epoxy sealed coil (top and bottom) – evacuated resin system formulated to match the coefficient of thermal expansion of the coil.
  • Flexible, polyester insulation system allows coils to withstand mechanical and thermal shocks.
  • UL listed 220°C rated insulation system for turn and layer protection.
  • Vacuum and pressure processed coils reduce operating temperature and   corona level.
  • Tough, flexible polyester cladding assures reliable operation in contaminated and humid environments.
  • Circular coil construction for best short-circuit and impact-loading strength.


VTC Developed UNIClad® to operate under demanding applications in increasingly harsh environments. Because it is designed to withstand industrial fumes and vapors, fibrous and particle contamination, high temperature and humidity, short circuit forces, and electrical voltage impulses, UNIClad® is the cost effective alternative to liquid filled or cast coil transformers. UNIClad®. For power, rectifier, drive isolation and generator exciters up to 15,000 KVA, 35 kV class.

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