Category Archive: Uncategorized

Aluminum vs. Copper Wire: Which One Is Right for My Transformer Winding?

At Sam Dong, we are a domestic producer of high-quality oxygen-free, high conductivity (OFHC) and electrolytic tough pitch (ETP) copper wires. These materials find application in a wide range of magnetic product applications, including as winding wires in transformers.

Winding wire—also referred to as magnetic wire or enameled round wire—refers to wire coated with a thin layer of insulation and wound into a coil. It is a key component in transformers and other magnetic equipment (e.g., inductors and motors). While many transformers utilize copper windings, some use aluminum ones. Below, we provide a comparison between the two to serve as a helpful guide for readers that needs assistance choosing the one that is best for their needs.Aluminum vs Copper

Overview of Aluminum Wiring

Aluminum wiring is lighter in weight and lower in cost than copper. However, since it is usually incorporated into bigger and, consequently, heavier transformers, the overall benefits of these qualities are minimal. Additionally, its few advantages are often outbalanced by its many disadvantages. For example:

  • The electrical conductivity and thermal conductivity of aluminum are less than copper. These qualities make the aluminum windings less efficient, which can lead to higher operating costs, and more prone to high hot spot temperatures, which can lead to shorter operating lives.
  • Transformers wound with aluminum produce more noise during operation than those wound with copper, which can lead to worse working conditions for system operators.

Overview of Copper Wiring

While copper wiring is heavier than aluminum wiring, it is often used to make smaller and lighter transformers. This is because copper offers higher electrical conductivity levels than aluminum. The resistivity of copper is 0.6 times that of aluminum. Therefore, the cross-section of an aluminum conductor needs to be 1.66 times larger than that of a copper conductor to demonstrate the same amount of resistance. As a result, an aluminum wound transformer would need to be much larger than a copper wound one to handle the same load.

Some of the other advantages copper wiring offers over aluminum wiring include:

  • Lower losses (due to better electrical conductivity) and temperatures (due to better thermal conductivity)
  • Greater reliability with regard to line and load connections
  • Better manufacturability since the generally smaller-diameters conductors are easier to handle

Superior Copper Wiring Products From Sam Dong

Both aluminum wiring and copper wiring are used in transformers. While aluminum may initially seem appealing due to its lighter weight and lower cost, copper is the better option. Its higher conductivity alone makes it more efficient and cost-effective. However, it also offers many other advantages that benefit companies who use transformers, such as easier maintenance, longer working life, and quieter operation.

Want to learn more about why copper wiring is the superior choice for transformers? Ask the experts at Sam Dong. Equipped with extensive experience manufacturing and distributing copper winding wires, we can answer and address any questions or concerns you may have about them. For information on our transformer wire products or assistance choose one for your transformers, request a quote today.

What Is a Superconducting Wire?

Since 1977, our company has been producing Oxygen Free High Conductivity Copper (OFHC) components, materials, and stock blanks for an extensive variety of industrial applications. Our USA facility specializes in OFHC rods and wiring, as well as superconducting wire. Superconducting wire offers superior conduction of electricity with minimal inefficiency, making it a popular choice for energy generation and critical applications. Our magnesium diboride (MgB2) wire is a superconducting wire material that also withstands high temperatures.

Types of Superconducting Wires

Superconducting wires are unique materials that have zero electrical resistance below certain temperatures called a transition temperature. This temperature changes depending on the material and other physical attributes of the wire. There are three main categories of superconducting wires, based on the transition temperatures thresholds they must reach to offer zero electrical resistance:What is a Superconducting Wire

High Temperature Superconducting (HTS) Wire

High temperature conducting wires are coated conductors that offer very efficient electricity handling below a set temperature level. Two of the most common materials for superconducting wires are bismuth strontium calcium copper oxygen (BSCCO) wires and Rare earth barium copper oxide (ReBCO) wires. However, second-generation wires are more refined and efficient formulas.

Medium Temperature Superconducting (MTS) Wire

Magnesium diboride is a common choice for medium temperature superconducting wire. The material is produced by melting magnesium and boron powders at magnesium’s melting temperature and then forming and finishing the wires. Magnesium diboride can be used to produce wires, tapes, and flexible ribbon cables.

MgB2 is our alternative to general commercial superconducting materials. It can handle high-temperature applications, including a transition temperature of 40 K. Not only is MgB2 easy to fabricate and work with, but the material is cost-effective and simplifies assemblies by removing the need for cryogens. MgB2 is a popular choice for operations with high operating temperatures of between 15K and 30K.

Low Temperature Superconducting (LTS) Wire

Low temperature materials are categorized as those that operate at 4 K and below. Low temperature superconducting wires are often made from niobium titanium or niobium tin. While the wire production itself is cost-effective, the low transition temperature it demands means that assemblies with LTS wire need cost cryogenic cooling components.

Superconducting Wire Applications

Superconducting wires are used throughout almost every industry to increase energy efficiency. Some of the most popular applications include:


Magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) equipment use superconducting wires. Biomagnetic devices are noninvasive medical technologies that allow medical professionals to observe and diagnose conditions.


Generator, wind energy turbines, transformers, and more all utilize superconducting wires to more efficiently generate, transport, and distribute energy.


Magnetic levitation (Maglev) systems use superconducting wires in the components controlling the electromagnets in the system. This can be used for high-speed train systems, such as the Yamanashi MLX01 MagLev train.


Superconducting wires dramatically improve the performance of engines in electric vehicles.

Nuclear Industry

Scientific and nuclear energy production facilities rely on high-quality superconducting wires to handle the power for nuclear fusion systems and particle accelerators. The Large Hadron Collider has superconducting wire.


Electric devices use superconducting wires, cables, and ribbons. Electric utilities also use superconducting wires in their transformers.

Superconducting Wire Properties and Specifications

Superconducting wires in all three temperature classes have unique properties that make them a cost-effective choice for increasing energy efficiency in the operation of electrical systems. Browse through this chart to learn more about the unique properties the wires offer:


Manufacturing methodPowder in tube (PIT) drawing
Filaments718 + ‘1’Cu
Length100 ~ 3000 m
Delivery time≤ 1 month (negotiable)
Diameter0.832 ~ 1.4 mmø
MaterialsExternal sheathMonel (Cu + Ni)
Inner sheathCu
Cu fraction30 ~ 45%
Heat treatmentTemperature650 ~ 675°C
Duration30 min
Ic (@4.2 K)3 T150 A275 A
6 T25 A30 A
Jc (@4.2 K)3 T3.4 x 105 A/cm23.3 x 105 A/cm2
6 T5.1 x 104 A/cm23.6 x 104 A/cm2
InsulationS-glass, Enamel

Superconducting Wire From Sam Dong

Superconducting wires are made from a variety of finely produced metal alloys that offer near-zero or zero electrical resistance in the right temperature conditions. This allows for better and more efficient performance of sensitive electronics in nuclear science, biomedical, and other fields. At Sam Dong, we produce high-quality MgB2 superconducting wires for clients around the world. Our team of engineers can create high temperature, medium temperature, and low temperature wiring for a multitude of industrial applications. Contact us today to learn more about our capabilities or request a quote to start your order.

OFHC Copper vs. ETP Copper

Sam Dong is a domestic producer of oxygen-free, high-conductivity (OFHC) copper rod. We utilize it to produce strip, shapes, and a variety of copper wire products, including bare wires, continuously transported conductors (CTCs), paper-insulated rectangular wires, special insulated wires, and more. Below, we highlight how this material compares to electrolytic tough pitch (ETP) copper. 

Overview of OFHC Copper

Oxygen-free, high-conductivity (OFHC) copper—sometimes referred to as simply oxygen-free copper—is a copper material that has undergone electrolytic refinement to reduce the oxygen contained within it to very low levels (typically less than 1/100 of a percent). The refined material can then be melted and cast into various components under highly controlled conditions that prevent exposure to air.

OFHC Copper vs. ETP Copper

Containing less than 10 ppm of oxygen and no copper oxide particles, OFHC copper offers the following advantages: 

  • Excellent corrosion resistance
  • Excellent electrical and thermal conductivity
  • Excellent resistance to hydrogen embrittlement 
  • High impact strength
  • High heat resistance
  • Good creep resistance
  • Good machinability and weldability
  • Suitability for use in high vacuums

Overview of ETP Copper

Electrolytic tough pitch (ETP) copper—also known as tough pitch copper or ETP copper—is the most commonly used type of copper. While it has a lower oxygen content than other copper materials, it is only considered 99.9% pure rather than 100% pure like OFHC copper. 

Some of the advantages ETP copper offers include: 

  • Broad application suitability
  • Excellent electrical and thermal conductivity
  • Good biofouling and corrosion resistance
  • Good machinability, solderability, and brazeability
  • Good aesthetic look

Key Differences Between OFHC and ETP Copper

Both OFHC copper and ETP copper have low oxygen levels. However, OFHC copper contains less than 10 ppm of oxygen, while ETP copper contains between 150 to 600 ppm of oxygen. Although this difference in composition may seem small, it can significantly impact performance in critical applications. For example:

  • OFHC copper offers a minimum of 100% IACS conductivity, while ETH copper offers a minimum of 99.99% IACS conductivity. 
  • OFHC copper can pass the close bend test that detects the presence of hydrogen embrittlement, while ETH copper cannot pass the close bend test. 
  • OFHC copper does not produce copper flakes when it undergoes manufacturing operations, while ETH copper does produce copper flakes when it undergoes manufacturing operations. These flakes can create unintentional conductive paths that lead to short circuiting in electrical and electronic devices and systems. 

The slightly higher conductivity of OFHC copper can be highly beneficial to a wide range of industries. For example, using OFHC copper over ETH copper to produce wires for transformers can reduce the overall diameter of the wire needed to achieve a certain efficiency. As a result, the amount of wire material required and, consequently, the overall cost of materials are reduced. The smaller size of the conductors also means manufacturers can make the overall transformer unit smaller, further reducing material costs. 

Partner With Sam Dong for All of Your OFHC Copper Needs

Want to learn more about how OFHC copper can benefit your application? Turn to the experts at Sam Dong. Equipped with over 40 years of experience producing OFHC copper rod domestically, our team has a comprehensive understanding of the material. Whether you need bare wire or critical magnetic wire, we can develop an oxygen-free copper wire solution that fully meets your requirements. 

For additional questions about this oxygen-free copper material, contact us today. To discuss your material requirements with one of our team members, request a quote. One of our representatives will be in touch to answer any questions.