Cable selection method of generic cabling system

Generic cabling is one of the key links of information network system. In order to ensure the high-speed and stable operation of information network system, it is particularly important to select high-quality and high-performance cables.

The cable selection should be based on the system requirements, technical performance, investment estimates and other factors, but in the wiring system, it should first determine the type of cable used and the structure of wiring (unshielded cable, shielded cable, optical cable or mixed use). Cables usually use Aluminum conductors with insulation and one or more layers of plastic sheath. The cable usually consists of 2 to 3600 pairs. Large logarithmic cables are usually used in backbone cabling systems and are suitable for voice and low rate data transmission. The maximum lengths of these cables for trunk and horizontal (hub to desktop) cabling systems are specified in the latest GB 50311-2007. It should be noted that these maximum length limits apply to all media. They do not consider the impact of performance differences due to different cable types and protocol types used in the network. In fact, the maximum cable length will depend on the application of the system, the type of network and the quality of the cable.

Method of cable selection in generic cabling system

Since it is a building, it will definitely use a lot of communication cables. As the nervous system of intelligent building, generic cabling system is the key part and infrastructure of intelligent building. It has a very close relationship with the planning and design, construction, installation and maintenance of construction engineering. It is like an information superhighway in the building. People can communicate and communicate conveniently, quickly and effectively. It can be said that the generic cabling system connects the communication, computer and various facilities and equipment in the intelligent building to form a complete set of whole, so as to meet the requirements of highly intelligent.

But then we have to consider a problem: fire prevention. Once a fire breaks out in the building, the heat and gas released by these cables will become a major safety hazard. Looking at several large-scale fire accidents in China in recent years, many of them are due to the fact that the victims can’t escape. The burning of cables emits poisonous acid gas. In addition, a lot of heat and smoke are released from the combustion, which makes it difficult for the victims to breathe and lead to tragedies. Therefore, in addition to considering the performance, fire protection and environmental protection are also very important reference factors when we select cables for generic cabling system.

Discussion on environmental protection requirements of PVC cables and wires

The use of non environmental protection cables is strictly prohibited in developed countries, and China also attaches great importance to this field. China’s relevant laws and regulations clearly require the use of PVC wires and cables in important buildings. Halogen free and low smoke crosslinked PVC wires and cables must be used to avoid heavy smoke and chlorine gas causing casualties in case of fire.

Environmental protection cable will effectively drive the development of cable industry, enhance the competitiveness of cable manufacturer, and make the cable industry more and more stable on the road of sustainable development in green practice and innovation. In recent years, China’s cable enterprises have gradually made efforts to environmental protection cables and low smoke and halogen-free cables. As far as possible, they do not contain heavy metals such as lead, cadmium, mercury, bromine flame retardants, harmful halogen gases, corrosive gases, less heat during combustion, and no soil pollution. Environmental protection cables will be more favored by the market, and will be recruited by power grid companies It is easier to get high order in the bid.

The user’s requirements for environment-friendly wires and cables can be summarized as follows:

1. Low content of lead and heavy metals is required

It is well known that lead and some heavy metals will have adverse effects on human health. In PVC formulation, additives such as lead, cadmium, barium and other heavy metal compounds are usually needed. However, since the 1990s, some developed countries and large electric companies have successively formulated laws and regulations. In the PVC wires and cables used, there are eight kinds of heavy metal content shall not be greater than the regulations. These new regulations not only bring new business opportunities to wire and cable manufacturers, but also bring serious challenges to PVC cable manufacturer.

2. Low smoke and low hydrogen oxide are required

Good flame retardant performance is a very obvious advantage of PVC wire and cable. However, when ordinary flame retardant PVC cable is on fire, it will release thick black smoke and a large amount of HCI gas, which will cause “secondary disaster” after the fire, and seriously affect personnel evacuation and fire rescue work. Therefore, in addition to the flame retardant requirements for wires and cables, the requirements of “low smoke” and “low HCI” will be put forward in some applications.

3. Low toxicity or non toxicity is required

In addition to lead-free and heavy metal free, non-toxic (or low-toxic) cables are required for some household appliances, medical and health appliances and children’s electric toys that may come into contact with food and blood products. This means that all constituent materials used in PVC formulations should be non-toxic. There are a lot of plasticizers in cable materials, but the non-toxic plasticizers must be used to manufacture non-toxic materials. Therefore, the requirements of this PVC material are higher than that of lead-free and heavy metal free materials, and the price is naturally more expensive.

4. Other prohibited items

At present, the regulations being reviewed by the EU impose restrictions on the following items to ensure that wires and cables meet the requirements of environmental protection. For example: 1) asbestos; 2) biphenyl and its ethers, polybrominated phenol; 3) polychlorinated biphenyls; 4) short chain (C10-C13) chlorinated paraffin.

With more and more attention to environmental issues, many countries have formulated a variety of environmental protection policies, so people prefer to use green cable. Low smoke halogen-free flame retardant cable material is one of the most popular environmental protection cables. Although China’s market demand for green cable is growing, compared with developed countries, China still has a long way to go in terms of relevant policy formulation and mandatory application. China should improve the environmental protection cable standards as soon as possible.