Litz Cable and It's Applications

Litz Cable is a type of cable that is composed of multiple, individually insulated strands. These strands can be woven or twisted together in a particular pattern to form a single conductor. The main aim of this cable is to minimize the skin effect and proximity effect in high-frequency applications.

Skin and Proximity Effect

The skin effect refers to the tendency of alternating current to flow more on the conductor surface than the entire cross-section, especially at higher frequencies. This effect in turn leads to increased resistance and energy losses.

The proximity effect refers to the tendency of current to flow in uneven distributions due to the presence of magnetic fields which are generated by the nearby conductors. The insulation between the strands in the Litz cable assembly prevents short-circuiting due to the fact of skin effect and the overall design reduces the proximity effect. Therefore, Litz wires negate these 2 negative factors.

Litz Cable Assembly Applications

The usage of Litz Cable finds its way into various applications where high frequency, efficient energy transfer and reduced losses are of paramount importance.

1. Medical Devices:

The properties of this Litz cable assembly make it ideal for medical devices such as medical imaging equipment or medical equipment that utilizes radio frequency technology (X-ray, MR Applications) which involves high-frequency signals.

2. Induction Heating Coils :

In applications such as Induction heating coils, high-frequency AC is used for the heat generation in the conductive materials. Litz cable assembly is employed to enhance the efficiency of energy transfer and minimisation of losses.

3. Communication Cables:

Employed in high-frequency transmission communicable cables where minimised losses and enhanced signal integrity are of importance.

4. Transformers:

This cable assembly is widely used in the winding of the transformers. This cable assembly design aids in the reduction of skin effect enabling for more uniform current distribution throughout the conductor, thus leading to less AC resistance and low power loss.

5. Converter and Inverter Applications:

The role of litz cables in converter and inverter applications is crucial for improving the performance, reliability and efficiency of power-driven electronics systems. In the Converters (Conversion of AC power to DC power) and Inverters ( Conversion of DC Power to AC power), these cables play a vital role in mitigating losses during high-frequency switching.

Processes involved in Litz Cable Assemblies

The manufacturing processes involved in Litz cable assemblies comprise of couple of key steps as follows

1. Strand Selection:

Initiates with the selection of fine wire strands that are made up of conductive materials such as copper etc.

2. Insulated Strands

The insulated strands are twisted or braided together in a specific pattern. This process in turn aids in the even distribution of current on the conductor.

3. Crimping

The crimping process involves compressing the metal sleeve around or along the conductor of the cable to form a mechanically secure, robust and electrically conductive connection.

4. Bath Tinning

This process involves immersing the cable in the bath of molten solder to attain the objective of enamel removal from the individual wire strands. It provides the means of coating the exposed wire strands with a thin layer of solder. This process improves the solderability, therefore establishing the electrical connection during the subsequent soldering process.

5. Soldering

Proper soldering is crucial to ensure reliable electrical connection and optimal performance in high-frequency applications. The tinned litz wire is soldered to the connector or other components, ensuring a reliable electrical connection.

6. Final Insulation

Additional protection is provided for mechanical stress, other environmental factors and abrasion etc. The litz wire is wrapped in Kapton tape, a polyimide tape which is known for its high-temperature resistance and dielectric strength. Additionally, these cable assemblies may utilize a High Shrink Tubing sleeve for additional protection.

7. Inspection and Testing

The reliability, quality and performance of litz cable assemblies are ensured via visual inspection and testing methods via Leakage Induction test, Hipot Test (High Potential Test) and Contact Resistance Test.

Leakage Induction Test: The electrical inductance is measured to ensure high-frequency performance.

High Potential Test: The cable’s insulation integrity is assessed through the application of high voltage for fault identification.

Contact Resistance Test: The electrical resistance of the cable connector interfaces is verified for reliable connections.

Benefits of Litz Cable Assembly

Here are some key advantages of Litz Cable Assembly are as follows

Similar to the benefits of individual Litz wire, litz cable assemblies are designed to mitigate the skin effect and proximity effect.

The consequent losses and increase in resistance caused due to the skin and proximity effect pave the way for a decreased efficiency performance. This arguably holds specifically in the case of wires. However, the adoption of Litz cable assembly enables the applications to operate at enhanced efficiency therefore serving as the ideal solution for high-frequency performance scenarios when compared to those constructed with standard copper wire.

Through the cable assembly, The losses coupled with these 2 effects are decreased, thus making it specifically valuable in applications where signal integrity plays a pivotal role. The decreased losses and improved efficiency of litz cable assemblies contribute to high-quality electrical energy transmission. This is particularly true in applications where maintaining the fidelity of transmitted electrical energy is critical. One of the notable benefits of these assemblies is the decrease in AC power loss in high-frequency windings.

Due to its capability to reduce the skin effect and proximity effect, this cable assembly facilitates the usage of high-current conductors with minimal resistance at extremely high frequencies making it a suitable choice for coil material in high frequency magnetic components.

Litz cable assembly facilitates the even distribution of current, therefore forming a pivotal role in eliminating the hot spots within the conductor. Hot spots are generally referred to as the localised areas where the temperature is considerably higher than the surrounding regions, therefore leading to inefficiency. The ability of these cables aids in the prevention of the concentration of the current, therefore maintaining a consistent temperature and improving reliability.

In addition, these cable assemblies offer flexible and customized designs. The cables can be tailored by the engineers to suit specific frequency ranges and applications to enhance optimal performance. The adaptability of these cables is ideal for various industries.

Processes involved in Litz Cable Assemblies

Litz Cable Assemblies are more costly than plain magnetic wire assemblies. So why choose them?

The production of litz cable assembly includes a more intricate and time-consuming manufacturing process as the individual strands need to be coated with insulating material, braided/ twisted together and also undergo an additional process of tinning compared to ordinary magnetic wires. They are often produced in smaller quantities for specific applications, leading to reduced economies of scale.

While the upfront costs involved in this cable assembly process are high, its long-term cost savings in terms of efficiency and decreased energy losses justify the investment. Various high-frequency applications utilizing the litz cable assemblies demonstrate a substantial increase in efficiency.

Litz Cable and It's Applications