The network market has been on the move for quite some time. Due to the progressive, ever faster data transfer rates systems are being developed with high pressure for ever higher bandwidths. The elaborations of the respective working groups in the standardization bodies lag behind the current state of the available technology a little. A current example is the cabling class E and F with category 6 and 7 passive components for copper cabling. The corresponding components of these categories have been available for some time

However, how can the user exactly weigh whether the individual component corresponds to the desired category or the selected passive network of the desired network class?

With the latest field-capable network test equipment, maximum bandwidths of 350 MHz can currently be measured with sufficient reliability, but not transmission frequencies of 600 MHz, as prescribed by category 7, or even higher. For the user, this means that he cannot verify his components by using network analyzers in the laboratory or on site without very expensive measurement effort. Rather, the user’s confidence in the quality of the products is required.

Often the price of the respective component is the decisive purchase criterion, not their electrical or mechanical quality. Fatal consequences are the result, up to the unsuitability of the resulting network for the intended application class. Especially for Class E networks, the compatibility of the individual components within the system is of utmost importance.

 

What characteristics make a data cable a high-performance solution and what are the advantage and the benefit for the user?

 

The characteristics of a high-performance cable are roughly divided into two areas: electrical and mechanical performance. The advantage is clearly in the system reserve, guaranteed by a large distance of the measured values compared to the prescribed category values.

Electrical Performance

Particular attention should be paid here to the cable characteristics with regard to the return loss and the signal-to-noise ratio (ACR). Half of all network problems are due to physical-level problems, ie mismatches, reflections in the passive network. The simplest and thus cheapest produced data cables have undesirably high manufacturing tolerances, which often only just meet the requirements of the standard. This is reinforced by the use of mostly lower-priced, mechanically less stable materials.

In times of classic “Category 5″ networks, the factor manufacturing tolerance, based on today’s standard, played a rather subordinate role. Cables and plug-in components were equipped with a high system reserve because “only” 100 MHz bandwidth could be realized. Only with improper handling or badly executed installation, it came here to failures.

The category 6 (250 MHz) marks the beginning of a new era. Above all the plug components based on RJ-45 are used up to their technical limitations. If a network of class E is to be set up, the term “system reserve” again becomes enormously important when it comes to the selection of suitable components.

Cables that just meet the limits of the categories are completely unsuitable for this purpose. The environmental factor of network installation is much too large to guarantee a safe function. The benefit of a high-performance cable is therefore undeniably high system security, which is achieved, among other things, by an extremely high stability of the geometry of the paired wires in the cable. The central position of the copper conductors and their tolerance in the core insulation material significantly influences the electrical transmission behavior in the range of high frequencies (200 MHz – 1000 MHz).

With modern production facilities, concentricities of more than 95% can be easily realized. This protects you from cable irregularities and unpleasant surprises when measuring the distances. A very high-quality standard that you receive from LEONI in all copper data lines. This protects you from cable irregularities and unpleasant surprises when measuring the distances. A very high-quality standard that you receive from LEONI in all copper data lines. This protects you from cable irregularities and unpleasant surprises when measuring the distances. A very high-quality standard that you receive from LEONI in all copper data lines.

Mechanical Performance

As a material for the cable sheath, PVC (polyvinyl chloride) has often been preferred because of the cost advantage in the past. In addition to the ease of handling during processing, PVC also has the advantage of being flame-retardant. This means that PVC cables meet the European fire safety regulations for the single fire test according to IEC 60332-1 (DIN VDE 0472 part 804 B). Specially compacted PVC also passes the stricter bundle fire test according to IEC 60332-3 Cat. C (DIN VDE 0472 Part 804 C). However, in these tests, only the fire propagation is checked, not the smoke or toxicity. The heating or combustion of PVC produces hydrochloric acid gas (HCl). At the same time, an increased evaporation of plasticizer components begins, which further accelerates the combustion process. Due to the halogens contained in the PVC dioxin can also be released, which in addition to the resulting carbon monoxide (CO) represents a high-risk to humans. The enormous smoke development additionally complicates the evacuation of the burning buildings

Example

In a large-capacity office with 25 workplaces and approx. 450 -500 m2 of office space, a total of approx. 3 km of data cables will be laid using three connection boxes per employee and an average 40-meter-long single cable section. This corresponds approximately to a PVC amount of 60 kg. In case of fire, this means that about 15kg of hydrochloric acid gas (HCl) is released. The assumed office space will smoke completely within a few minutes with a residual light content of a maximum of 5-10%. The liberated HCl gas is highly irritating and therefore dangerous to the eyes and lungs, which greatly affects the ability to escape the fire. Hydrochloric acid is also highly corrosive, ie it attacks metal surfaces, electrical equipment, and reinforced concrete. The destruction of the building by corrosion is usually many times greater than the damage caused by the fire.

  • FR ➜ flame retardant = flame retardant
  • NC➜ Non Corrosive = non-corrosive
  • LS ➜ Low Smoke = low smoke emission
  • 0H➜ Zero Halogen = No halogens

Polyolefins form the basis of these sheath materials. Two types are most common in the field of data cables and must be differentiated exactly according to the application:

On the basis of ethylene vinyl acetate (EVA) and the addition of aluminum hydroxide, a very suitable jacket material is created, the so-called TPE-O-FRNC material. It is completely halogen-free and non-corrosive, ie no dioxins or corrosive gases are released. Due to the additive aluminum hydroxide, water vapor is formed during flame treatment, which serves to extinguish the burning cable. Thus, cables with TPE-O-FRNC sheath achieve the requirements of flame resistance according to the bundle fire test IEC 60332-3 Cat. C (DIN VDE 0472 Part 804 C). The smoke development is very low compared to PVC and measured according to IEC 61034-1 and 61034-2. Both tests are necessary to demonstrate the classification of low levels of smoke. The absence of halogen must be checked in accordance with IEC 60754-2. Carbon monoxide (CO) is the most dangerous component for humans in case of fire. TPE-O-FRNC develops only about 1/5 of the CO volume compared to PVC.

Another alternative to PVC is the ethylene-ethyl-acetate (EEA). By adding the flame retardant component calcium carbonate (chalk), the flammability of the material is reduced. However, this polyolefin copolymer is much more flammable than EVA with aluminum hydroxide. It only achieves a maximum fire resistance for the single fire test according to IEC 60332-1 (DIN VDE 0472 Part 804 B). The only real advantage of EEA, in addition to the halogen-free, is therefore only in the price of materials, which is why above all extremely cheap data cables are offered on the market with this sheath material. The designation of these cables is often still FRNC. However, this material must be kept away from use in data networks since the fire safety according to the bundle fire test IEC 60332-3 Cat. C (DIN VDE 0472 Part 804 C) is not given. Especially in the horizontal and climbing area, where cable bundles are installed, the increased fire resistance is indispensable

Conclusion

It is, therefore, essential that a high-performance data cable is not only electrically perfect but also equipped with the highest quality materials. This is only guaranteed if all the above-mentioned standards are complied with and regularly checked. In order not to take any risks, you require a test certificate from an independent test institute! Because it is not only your confidence in the quality of the products required but also your control.