Unique electrical environment applications require unique ingredients in the make-up of their cables. Like baking a cake, the ingredients of a standard vanilla with white frosting sheet cake are a lot different than a carrot cake or a red velvet cake with strawberry filling. The overwhelming majority of Betty Crocker “boxed cake mix” cables are made with bare copper or tinned copper for their desired electrical conductivity and affordability. Some cables with higher temperature or corrosion resistance requirements are made with silver plated copper or nickel plated copper, but what happens when the temperature drops?

Figure 1: The overwhelming majority of Betty Crocker “boxed cake mix” cables are made with bare copper or tinned copper for their desired electrical conductivity and affordability. Source: Cooner WireFigure 1: The overwhelming majority of Betty Crocker “boxed cake mix” cables are made with bare copper or tinned copper for their desired electrical conductivity and affordability. Source: Cooner Wire

Device manufacturers with cryogenic applications require special conductor materials that will meet the challenges of extreme cold. Cooner Wire offers a wide range of conductors that are up for the challenge. They have made cryogenic cables with copper nickel (CuNi 70/30) and niobium titanium (NbTi) as conductors. The CuNi is desirable because it retains its ductility at low temperatures and exhibits good thermal conductivity, which is advantageous for heat exchangers. Other common conductor materials get fragile and break at cold temps. The NbTi has zero resistance at 4° Kelvin and below.

The superconducting NbTi is famously used in the Large Hadron Collider (LHC) magnets. The LHC is a ring of superconducting magnets that is the most powerful particle accelerator in the world. It generates a strong magnetic field that accelerates and collides particles at very high speeds to study the fundamental particles and forces of nature. These particles are accelerated to a speed close to the speed of light. The accelerator sits in a tunnel 100 meters underground at CERN, the European Organization for Nuclear Research, on the Franco-Swiss border near Geneva, Switzerland. This is the same NbTi superconducting material used in some of Cooner Wire cryostat cables on a much smaller level.

This is not to be confused with nuclear fusion. That’s a process where two light atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy in the process. Nuclear fusion is the process that powers the sun and other stars. While the technologies used in particle accelerators like the LHC and nuclear fusion reactors share some common principles, they serve different purposes and operate on different scales. The LHC is not designed to be used as a nuclear fusion reactor. Nuclear fusion reactors are specifically designed to confine and control the fusion reactions to produce energy.

Research into nuclear fusion is ongoing, with the goal of developing practical fusion reactors that can generate clean and abundant energy. While the LHC is not used for this purpose, it does contribute valuable insights and technologies that can be applied in various fields of science and engineering, including nuclear fusion research.

The insulation of choice for cryogenic applications is ethylene tetrafluoroethylene (ETFE) — DuPont Tefzel. ETFE has proven to be the best performer in these cables. Other fluoropolymers like tetrafluoroethylene — TFE (Teflon), perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP) tend to get brittle at cryogenic temperatures. ETFE has held-up well in these cold environments.

The shielding material chosen by cryogenic device manufacturers in cold environments is either stainless steel or phosphor bronze. Stainless steel is chosen because it retains its engineering properties, which allows them to maintain their ductility and impact toughness. As the temperature drops, stainless steel’s tensile and yield strength will actually increase. Phosphor bronze is sometimes chosen because of its combination of low thermal conductivity and fair electrical conductivity. This allows for electrical connections to devices at very low temperatures without adding too much heat. Phosphor bronze wires are also suitable for almost all cryogenic applications because of their low magnetoresistance, which makes them ideal for use in magnetic fields.

Another example of needing a different conductor ingredient arose when a device manufacturer was having arcing issues with a grounding application for a highly sensitive environment. Cooner Wire was able to source a pure silver raw material wire supplier and ultimately offered a ground strap made with pure silver. Silver will oxidize, but it has a nice property that its oxide is conductive. It’s expensive, but it works.

Most customers come to Cooner Wire for flexible cables. There is a difference between flexibility and flex life. The company achieves the flexibility in their cables by using finely stranded wire (high strand counts) and soft silicone rubber or PVC insulating compounds. Many of these flexible cables are made with tinned copper conductors, which have a tensile strength of 35K psi. Customers in the robotics industry that are looking for increased flex life (high cycle counts) require high strength copper alloy conductors with a 90,000 psi tensile strength. A conductor with a higher tensile strength will yield a higher flex life and break strength. Cooner Wire stocks many different flexible multi-conductor cables in different AWG sizes that can be purchased in prototype lengths for ambitious R&D engineers who don’t want to wait. Samples are available for flexibility evaluation by request. These are just some of the considerations that Cooner Wire takes into account when designing cables in partnership with their customers.

Being able to offer all of these diverse conductor materials and insulations sets Cooner apart from other custom cable manufacturers. If customers have settled for rigid tinned copper conductors in the past and feel a different conductor material will yield better performance for their device, a Cooner Wire cable design expert can help. Visit their website today.