Where Quality Meets Transformers

In most conventionally manufactured transformers, electrical insulation within a winding section relies almost entirely on the enamel coating of the copper wire. Additional insulation—such as tape or film—is typically applied only between winding sections.

Within each section, the copper wire is often wound in a semi-random manner. This means that two adjacent wires can experience significant voltage differences. The result? A higher risk of short circuits and inconsistent inter-winding capacitance from one transformer to another.

Because the majority of transformers worldwide are built this way, the industry has long associated transformers with variability and reliability concerns. These issues are not simply the result of poor quality control—they are inherent in the construction method itself. Even rigorous quality management systems, such as ISO 9000, can only marginally reduce these risks.

A Different Approach to Transformer Design

At Lundahl Transformers, reliability and repeatability are not afterthoughts—they are built into the design and manufacturing process from the very beginning.

Our transformers are known for their consistency and long-term performance, thanks to a carefully engineered production philosophy that challenges conventional methods.

1. Layer-by-Layer Open-End Winding

We apply an open-end winding technique with insulation between every single layer of copper wire—even for the thinnest wire dimensions. This results in several critical advantages:

• Ordered winding structure
  Wires are laid in precise, well-defined layers with no crossovers. This improves the fill factor—even with additional insulation.

• Reinforced insulation where it matters most
  Extra insulation is placed vertically, strengthening areas exposed to high voltages and mechanical stress.

• Controlled electrical environment
  Each wire is in close contact only with neighboring wires of similar voltage within the same layer.

• Lower, predictable winding capacitance
  Reduced and highly reproducible capacitance improves performance consistency across units.

Built-In Quality at Every Stage

Quality control at Lundahl goes far beyond final inspection:

• Pre-molding isolation testing
  Every transformer is tested before molding to identify and eliminate units with insufficient isolation margins.

• Ceramic casting for mechanical stability
  Naked windings are fixated using a specially developed ceramic molding process.

• Vacuum-pressure impregnation
  Transformers are impregnated using a solvent-free epoxy resin through a controlled pressure and vacuum cycling process. This ensures deep penetration and long-term durability.

• Individual final testing
  Each transformer undergoes comprehensive testing for electrical performance, malfunction, and isolation breakdown.

Experience That Makes a Difference

Our production is carried out by a highly experienced team, with an average employee tenure of more than 10 years. This depth of expertise plays a crucial role in maintaining the precision and consistency our customers expect.

Staying True to Our Principles

We do not compromise on our vision of how an ideal transformer should be designed and manufactured. For this reason, we choose not to produce products—such as toroidal transformers—where our design principles cannot be fully applied.

Our approach is unique enough that we have developed and built much of our own production equipment in-house, including specialized winding machines.

Looking Ahead

Like all companies, we depend on the trust and satisfaction of our customers. Maintaining that confidence drives everything we do.

Looking forward, we are focused on:

• Further documenting key production steps

• Continuously improving both products and processes

• Delivering maximum long-term value to our customers

Quality is not a feature—it’s a philosophy we continue to refine.

Per Lundahl
Managing Director