In this edition of Ask the Legends, the engineering team at New England Wire Technologies breaks down the fundamentals of Litz wire, where it comes from, and what technical parameters are required to specify a custom build.
The name “Litz wire” originates from the German word Litzendraht, which translates to “braided,” “stranded,” or “woven” wire. To understand its construction, consider basic magnet wire: a single solid conductor (typically copper or aluminum) coated with a thin dielectric enamel film. When two or more of these individually insulated magnet wire strands are bundled and transposed in a specialized pattern, it becomes Litz wire.
The primary engineering objective of Litz wire is to reduce alternating current (AC) losses at high operating frequencies—specifically counteracting the skin effect and proximity effect that degrade efficiency in solid conductors.
When developing a custom Litz wire solution for transformers, inductors, solenoids, or specialized motor windings, five key parameters dictate the optimal construction:
- Operating Frequency: Governs the individual strand diameter (AWG) required to ensure strand radius remains smaller than the electromagnetic skin depth.
- Thermal & Temperature Class: Dictates the chemical composition of the strand enamels and outer insulation materials (e.g., Class 155°C, 180°C, or 200°C).
- Dielectric Voltage Requirements: Determines the necessary insulation barrier and voltage standoff capabilities.
- Outer Insulation Style: Tailored to the operating environment, ranging from textile serves (nylon, polyester, Nomex) to wrapped dielectric tapes (Kapton, Mylar) or extruded thermoplastic jackets (ETFE, FEP, PFA).
- Dimensional Boundaries & Final Outer Diameter (OD): Ensures the finished conductor fits strictly within the available bobbin winding window, toroid aperture, or coil geometry.
Key Technical Takeaways
- Etymology & Definition: Derived from Litzendraht (woven wire); constructed by bundling and transposing two or more enamel-coated magnet wire strands.
- Magnet Wire Foundation: Built from fine copper or aluminum strands individually insulated with thin dielectric enamel films.
- AC Loss Reduction: Specifically engineered to mitigate high-frequency skin and proximity effect losses that occur in solid conductors.
- Essential Design Inputs: Specifying a custom Litz construction requires defining operating frequency, thermal temperature rating, dielectric voltage, insulation type, and maximum finished OD.
- Insulation Flexibility: Can be left bare-bundled or packaged with protective textile servings, wrapped barrier tapes, or extruded outer jackets.
Episode Transcript – What is Litz Wire? Ask the Legends!
Welcome to Ask the Legends
Welcome to “Ask the Legends: The Legends of Litz.”
Litz wire comes from the German word litzendraht, which means braided or woven wire.
Magnet Wire vs. Litz Wire Construction
But to first understand that, we need to take a look at magnet wire.
So magnet wire would be one single strand of a wire, generally copper or aluminum, that has an enamel coating on it. So this one individual strand would be magnet wire. When you take two or more of them together and group them, it becomes Litz wire.
Operating Frequency and AC Loss Reduction
So the applications for Litz wire: if you have an application where you need to reduce your AC loss at frequency, Litz wire should be a consideration.
Key Factors for Custom Litz Wire Design
Some key factors when we would be looking to design a Litz construction would be:
- We’d need to know the operating frequency you’re working in
- If you have temperature requirements
- Voltage requirements
- Whether or not that has to be insulated—and we have various insulation options, like this is a textile, tapes, or extruded insulations
- And we’d want to understand what your final OD is, especially if you’re going to be winding this for a bobbin used for a transformer or solenoid.
So if you have an application that’s going to require Litz wire, give us a call. We’ll work with you for the details of your construction and design the best Litz wire for your application.
