Ethernet cable performance

In today's article, we will discuss the ethernet cable performance, specifically focusing on how the tensile strength of ethernet cables can be reflected through various ethernet cable performance indicators.

 

 

Ethernet cables, also known as twisted pair cables, consist of four pairs of twisted wires. The tighter the twist of these four pairs, the better the shielding performance and the stronger the ability to counteract external interference, resulting in higher quality cables. For example, Cat6 cables have a tighter twist pitch than Cat5e cables, making them superior in performance. However, for shielded ethernet cables, there is already a shielding layer inside, so the twist pitch is not a concern. For unshielded cables, we can use a wire stripper to expose the four pairs and examine their twist pitch. High-quality cables minimize crosstalk between each pair by tightly twisting them in a counterclockwise direction, with each pair having a different twist pitch. The complexity of this manufacturing process increases the cost of the cables. Some unscrupulous manufacturers cut corners by using a twist pitch of one centimeter or more, which increases crosstalk and degrades performance. Sometimes, you can directly observe the twist pitch from the cable's exterior; a tightly twisted cable will show clear marks of the four pairs.

The twist pitch is the distance between the outermost points of two twisted wires. Poorly twisted cables have a larger twist pitch, meaning the wires are not tightly twisted. Well-twisted cables have a smaller twist pitch due to the tight twisting of the wires.

A smaller twist pitch reduces crosstalk between cables-a principle most of us learned in middle school physics. If you're not sure, a quick look at a diagram should clear things up. Most CAT5E cables we use are UTP unshielded cables, and their interference prevention mainly depends on the twist pitch of the pairs, making the twist pitch a crucial reference for judging the interference resistance of unshielded cables.

 

When reviewing various technical documents, you'll see many manufacturers promoting both single-strand (a single solid conductor) and multi-strand (made of multiple thin conductors) cores, with multi-strand cores seemingly having more advantages. How should one choose? Multi-strand cores offer better flexibility and can withstand repeated bending, but they may introduce electromagnetic interference. However, the use of network cables should be considered based on a combination of factors.

Let's break down the differences between the two from different angles.

 

Structurally, single-strand cables use a single solid wire, whereas multi-strand cables are composed of multiple thin conductors, giving multi-strand cables better flexibility and resistance to breaking from repeated bending, which is their main advantage. However, multi-strand cables can cause electromagnetic interference due to irregular current paths, potentially affecting signal quality. Additionally, multi-strand copper conductors may cause signal attenuation, especially over long distances, leading to signal distortion and loss. Single-strand conductors have less interference and can achieve longer transmission distances. If stable transmission is your priority, single-strand copper conductors are the way to go!

When purchasing ethernet cables, the multi-strand design is not to cut corners but to meet specific usage needs. Choose the appropriate cable based on actual usage scenarios!

 

 

When using ethernet cables, you might notice a white string, known as the rip cord. The rip cord is a nylon string inside the cable for pulling and stripping.During installation, if you need to pull the cable, without a rip cord, all the tension would be on the internal wires, potentially causing them to break. Many manufacturers add a tensile rip cord inside the cable during production. Don't underestimate this nylon cord; its tensile strength is greater than the metal wires inside and much higher than the PVC outer sheath.

If the rip cord breaks, it means the cable was subjected to too much tension during installation, which can thin or snap the copper core, making the cable useless for signal transmission. The rip cord also helps in tearing open the cable's outer sheath. Many installers rely on the rip cord to strip the cable's outer sheath quickly and efficiently. By cutting a small section of the outer sheath to expose the rip cord, it can be used to pull off the entire outer sheath, avoiding damage to the internal wires when using knives or scissors. Seasoned cable installers swear by this nifty trick.

 

The tensile strength of a ethernet cable is an important indicator. Many ethernet cables advertise their tensile strength in terms of Newtons. This indicator depends not only on testing but also on the cable's structure and material. Generally, ethernet cables are made of twisted metal conductors (usually copper or aluminum wires) with an outer layer of insulating material. This structure allows the cable to transmit data while also providing a certain level of tensile capacity.

So, just how strong is a ethernet cable's tensile strength? This mainly depends on the cable's material, structure, and manufacturing process. Typically, copper cables have higher tensile strength than aluminum cables, and tightly braided cables can withstand more tension than loosely braided ones. Additionally, the sheath material of the cable also affects its tensile strength.

Why is high tensile strength important in ethernet cables? When external force is applied to the cable, the internal conductors are stretched until they reach their limit. This limit represents the material's tensile strength. On a macro level, tensile strength refers to the conductor's ability to resist deformation. When the external force exceeds the conductor's tensile strength, the conductor will break. Therefore, tensile strength can be seen as the cable's ability to resist damage. The magnitude of tensile strength is influenced by various factors, all of which protect the internal conductors from deformation and ensure that the conductive performance remains unaffected.

 

The tensile strength of a ethernet cable is closely related to its outer material. So, which materials have high tensile strength? First, let's introduce high-density polyethylene (HDPE). Most ethernet cable inner sheaths are made of PE polyethylene. HDPE has a linear, non-branching structure with strong intermolecular forces, resulting in hard and strong physical properties, as well as good chemical resistance.

The tensile strength of polyethylene depends on its molecular structure, material processing, and form. Typically, polyethylene has a tensile strength ranging from 20 MPa to 30 MPa. However, different types of polyethylene exhibit different performance characteristics. LDPE has a tensile strength between 13 MPa and 20 MPa, with an elongation rate of over 700%. HDPE has a tensile strength between 20 MPa and 28 MPa, with an elongation rate of over 500%.

PVC, or polyvinyl chloride, is a synthetic resin that's a thermoplastic with decent tensile and compressive strength. These mechanical properties make PVC a popular material in many industrial applications. The tensile strength of PVC is the maximum stress the material can endure under tensile force without breaking. The tensile strength of PVC is influenced by its molecular structure, type of additives, and processing conditions. Generally, PVC has a tensile strength between 30 MPa and 50 MPa, but this can be increased by adding reinforcing agents such as glass or carbon fibers.

LSZH sheathing, known for its low smoke and zero halogen properties, also boasts excellent tensile strength. One of the characteristics of LSZH materials is their tensile strength, which makes them perform well in various application environments. Specifically, the tensile strength of LSZH materials reaches 1000 N, demonstrating their strength and durability under external tensile forces. This tensile strength is key to shielding cables from external physical stress and tension, particularly in high-durability applications.

 

The cross skeleton in ethernet cables is primarily used to support and protect the internal structure of the cable. During data transmission, the cable must endure various external and internal pressures and tensions. The cross skeleton enhances the cable's strength and stability, preventing damage or breakage, thereby ensuring the stability and security of data transmission.

Additionally, the cross skeleton helps maintain the correct shape and structure of the cable, preventing twisting or deformation, and ensuring the accuracy and speed of signal transmission.

In extreme conditions, like high-temperature settings or flammable areas, the cross skeleton also offers fire resistance and can handle high heat.

The structure of the cross skeleton ensures that the four twisted pairs inside unshielded cables are evenly distributed, enhancing the cable's balance characteristics. This balance is crucial for improving the stability and accuracy of signal transmission. During data transmission, various factors can cause signal fluctuations or distortions. The cross skeleton ensures that the signal remains balanced during transmission, reducing the likelihood of fluctuations and distortions.

Some unshielded cables use a cross skeleton with internal flame-retardant materials. This design enhances the cable's fire resistance and lowers the risk of fire incidents. In challenging environments, like high-temperature or flammable areas, the flame-retardant cross skeleton ensures the cable operates safely and stably. The four crossbars of the skeleton separate the four twisted pairs inside unshielded cables, maintaining their spacing and ensuring even distribution. This setup cuts down on interference and crosstalk between pairs, boosting signal transmission quality. In high-speed data transmission, keeping the spacing between pairs is crucial, as it prevents signal attenuation or distortion caused by mutual interference during transmission.