Magne-Seal Premium-Duty Sealed Insulation System
MTC’s exclusive Magne-Seal design provides the solution for premium-duty sealed transformer needs in heavy commercial and industrial applications. It combines the environmentally friendly, cost-effective, flexible design benefits of dry-type transformers and the protection capabilities of cast coil and liquid-filled transformers.
The Product

Magne-Seal begins in the coil winding process using special techniques to install materials that create a seal at the bottom of each winding layer. Coils are then pre-baked to thoroughly dry them for varnish processing. During a two-step vacuum pressure impregnation (VPI) process, every layer of conductor and insulation material is filled with varnish like a column. After baking the coils to cure the VPI process, a final high-build polyester varnish finish is applied.
The finished Magne-Seal product provides coils that are completely sealed against the environment. All Magne-Seal materials – Nomex insulation, polyester varnish, sealing materials – are fully rated for a 220º C insulation system.
Environmental Advantages
- No Fluid Containment Required – Magne-Seal is a dry transformer and contains no fluids. It doesn’t require expensive basins to contain potential spills and eliminates the concern of transformer fluids escaping containment barriers.
- Fire Resistant – MagneSeal has successfully passed fire testing that verifies the materials used to construct it do not support combustion.
No explosion barriers or blast containment are required.
Design Advantages

- Higher Overload Capability – All the materials used in the Magne-Seal insulation system are fully rated for 220º C. Epoxy materials used in cast coil and other designs are rated for much lower temperatures. Magne-Seal is able to deliver 15-30% more overload capacity than designs that use epoxy materials.
- Smaller Footprint – The Magne-Seal processing system doesn’t restrict the use of coil cooling ducts. This allows MTC designers to provide an efficient convection cooling system that requires less floor space. Magne-Seal footprints are typically 10-20% smaller than cast coil footprints.
- Flexibility – Since Magne-Seal isn’t cast in a mold, designs aren’t restricted by mold sizes. MTC designers have available a full range of coil geometries and winding configurations to provide electrical parameters and physical dimensions exactly as specified.
- Cost Effective – No molds, expensive casting equipment, or epoxy insulation are required. Magne-Seal provides a sealed coil transformer efficiently and effectively. An experienced MTC sales staff is available to show you the cost advantage.


