Overview of Structured cabling

With the rapid development of communication technology and information industry, intelligent Building (ib,intelligent building) has more and more use of computer, control equipment and communication equipment, all equipment of building, voice exchange, data terminal, network equipment, video equipment, HVAC, fire fighting system, Security monitoring, power systems and thermal systems, such as intelligent management and control, to achieve interoperability information, sharing resources. Such a lot of systems and equipment, its information type and information distribution complex and changeable, so must establish an effective wiring system, different control equipment, switching equipment, network equipment and computer equipment and other interconnected.

Networks are connected systems that connect separate devices together and enable them to share information and resources. The correct design and implementation of a network system can improve the speed and reliability of communication, so that a system to work more efficiently. The construction of the network should meet the requirements of the published national and international standards, and should be able to evolve and upgrade according to changes in business requirements.

With the great use of computers, people pay more and more attention to the topic of network and wiring. In the past, desktop computers were usually working independently, and now that has changed. At present, more than 50% of the commercial computers are connected to the local area network, they can greatly improve the efficiency. A local area network can connect a computer to a server and peripheral, or provide a signal channel for sensors, cameras, monitors, and other electronic devices. If these links are based on a temporary basis, the workspace will soon be full of all sorts of indistinguishable cables, and it is almost impossible to troubleshoot and maintain them.

Wiring Preparation

Everything needs to be well prepared before it can be implemented. The preparation of cabling system involves the factors of load assessment and planning, target life cycle and technical index.

1. Load Assessment and Planning

The choice of network and cable types is determined primarily by the type of devices that need to be connected, their location, and how they are used. Before you begin planning, it is necessary to give a description of the potential load on the network. When a network needs to serve multiple systems, it should carefully consider the peaks of their mixed data traffic. (Computer science)

2. Target life cycle

The average target life cycle for cabling systems is 15, which is consistent with the refurbishment cycle of major buildings. During this time, there will be significant changes in the system's computer hardware, software, and usage patterns. The requirements for network throughput, reliability, and security must be increased.

3. Development of technical indicators

Use method; Number of users and possible growth; The user's location and the maximum distance between them, the likelihood of changes in the user's location, the connection to current and future computers and software, the available space for cabling, the total investment of network owners, regulatory and security requirements, and the importance of preventing service loss and data leakage

Cabling Selection

1. The importance of wiring system

Cabling is one of the key components of any networked system, so policymakers must be prepared to use 10% of total network investment in this area. Investment in high quality cabling and network design is definitely worth the money.

2. Selection of cables

The type of device connected to the network and the traffic load on the cable are key factors in selecting the cable. In the wiring system should first determine whether to use shielded cables, unshielded cables, optical cables, or combine them together.

Cables usually use wires with insulating layers and use one or more layers of plastic skins. A cable typically consists of 2 to 1800 line pairs. Large-logarithmic cables are commonly used in backbone cabling systems, which are particularly suitable for use in voice and low speed data applications.

3. Length limit

The maximum length of these cables in the application of the trunk and level (hub to desktop) cabling system is described in detail in the International standard is0/iecis11801.

4. Size limit

It is also important to check the free space for cable alignment before determining the type of cable. Factors such as size, weight and shielding flexibility depend mainly on whether the cable is metal foil or the preparation of the shield, and how many wires are used in the cable.

5. UTP Cable

unshielded twisted Pair (UTP) can transmit data at a 622Mbps or higher transmission rate. This makes it possible to use a lower, smaller cable in an application that uses only shielded cables. UTP cables reduce EMI interference by more closely matching cables to the wire. This cable is called the balance circuit.

6. The balance of the circuit

In an ideal balance circuit, the noise voltage introduced in the conductor is zero, so that the signal transmission between the line pairs will not interfere. However, this ideal situation is not fully implemented, the cable signal-to-noise ratio (SNR) is used to measure the cable in the presence of noise signals in the case of signal quality indicators.

Shielding cable due to the existence of shielding, so its balance is poor, so good shielding integrity and good grounding for shielded cable is very important. High-quality UTP cable can achieve good balance circuit characteristics without grounding or the whole circuit need not be shielded. Because optical fibers transmit signals through light waves, they are unaffected by any form of electromagnetic shielding.

7. Selection of optical cables

In applications where the transmission rate requires more than 155Mbps and requires longer transmission distances, the fiber is usually the best choice. Optical fiber has the advantages of small size and durability,

But its cost is higher than other types of cable. In most networks, cable is generally used as a trunk line, and UTP cable is used to act as a horizontal connector.

Wireless LANs can be an alternative to systems that do not easily install cables due to installation time, space, or other limitations.

Cabling Planning

Most cable manufacturers prescribe a 15-year shelf life for their products. During this period of time, change is unavoidable and cannot be accurately predicted. The only solution is to design the network in order to meet the requirements of network changes and growth to plan accordingly.

1. Investment protection in the future

Under normal operating conditions, the new network should not limit system upgrades during the 15 building renovation cycle. A well-designed cabling system can withstand data traffic that is 10~15 times higher than most LAN transmission rates. This will allow the use of new network technologies without altering the wiring system.

2. General wiring System

The main advantage of universal cabling system is that users can use it to connect different manufacturers ' devices to the network. It also allows users to run several separate systems on the same cabling network. For example, users can build a system of telephone, computer and environment control on a cabling system.

3. The structure of the wiring

Universal cabling and mass cabling are the core content of structured cabling, and Lucent Technology (formerly At&t) and its Systimaxscs solutions are pioneers in this respect. It uses an open architecture platform that supports standards and protocols for all major private and non-private networks. Systimaxscs uses UTP cables and optical cables as a transmission medium, with a star topology and a standard socket for end-up. Systimaxscs uses a simple cable type, composed of a network of modular, without affecting the use of users can easily expand or change the network.

4. Network Parts

A distribution frame located within each building or complex is a component used to quickly access or evacuate a network of computers, peripherals, network hubs, and other devices. It can save a lot of costs in a company where the structure and layout are constantly being adjusted. ----

Avoid interference

Each active electronic and electrical device can generate electromagnetic interference to disrupt network communications. With the increasing use of electronic equipment, the problem has become more and more prominent. In the choice of cable and cable cabling considerations, how to prevent EMI interference to protect communications is also a key issue.

There are two ways to measure the crosstalk performance of a cable: the crosstalk between line pairs and the Powersum crosstalk. The crosstalk between line pairs is only used to measure the maximum disturbance caused by the centerline of the cable.

1. Powersum

Powersum to reflect the crosstalk in a more authentic context. It is a method for measuring the transmission of all wire pairs on a cable across multiple lines. Powersum is the only way to correctly test Crosstalk performance for cables with more than 4 pairs of cable centerline.

2. Signal-to-noise ratio (SNR)

The signal to Noise ratio (SNR) is used to measure the suppression of EMI interference in the system. The higher the signal-to-noise ratio of the network, the less the risk of the network data transmission error.

3. Cable alignment

All network components, including connectors and wiring racks, must have some measures to resist EMI interference. This is especially true when you build a network with products from different vendors.

Design and Installation

After deciding which network configuration and cable type to use, the rest of the work is to carry out a specific system design and installation. The first step is to determine the structure of the network, which is usually a relatively straightforward task.

1. The collapsed trunk

The typical structure of the network may be different. For example, a collapsed trunk structure can be used to facilitate the placement of servers, hubs, and wiring racks in a compact, secure area, which saves space and improves the physical security of the system.

2. Redundancy

If the system is used to perform critical tasks, then the system may need to use more than one trunk to achieve the mesh network design, so that the system has a certain degree of redundancy.

3. Physical limitations

Cable types used in trunk, horizontal cabling, and mass cabling have been selected at an earlier stage of planning. In the installation, design, and planning phases, it is important to consider its physical limitations when selecting a cable type.

4. Cable alignment

Cable manufacturers will give the cable the minimum bending radius and the maximum tensile and other indicators, they would also be such as heat sources, EMI sources, and other aspects of the relevant reference suggestions. What other networks can be used to share pipelines, especially where there is a distribution of power cables, should pay special attention to EMI issues.

5. Walking line Drawing

A complete cabling diagram must be prepared before wiring system is installed. It has a great help to the installer, and it also has great reference value for the maintenance, expansion and fault lookup of the network in the future.

6. Cable identification

The actual labels on the chart and cable should be referenced to each other. Planning and labeling work can be done by the installer or the Interior system department. There are a lot of software packages that can help people to do this work.

7. Installation and Access

The design of the network should follow the principle of easy installation and access, and should consider giving the cable sufficient support and protection. The manufacturer's application guide should be designed to ensure that its products meet these requirements, and they should also take into account the requirements of the national and international standards associated with the cable pipeline, and the site installer is also responsible for ensuring that the code requirements and standards of the building are met. Alternative cable support and protection methods include: Underground pipelines, movable floors, cable pipelines, pallets and grooves, ceiling wiring, border crossings.

8. Piping and ceiling wiring

Piping and ceiling wiring should usually be carried out in accordance with the requirements of the general standard. For example, in eia/tia569, the maximum length of the pipe is 30m, and the number of 90° bends in the cable hauling point should be less than two. The pipe internal bending radius must be 6 times times the pipe diameter, for pipelines larger than 50mm diameter, the bending radius should be at least 10 times times its diameter.

9. Line Channel

The use of appropriate equipment and procedures during cable installation can reduce tension on the cable and prevent cable damage. When you install the system, you should follow the cable pipeline filling method given in the line channel and piping manufacturer's guide.

10. Cable support

Ceiling wiring, piping, trays and other piping hardware must be used above ceiling ceilings. In addition, the cable in no more than 1.5m high space, you can use J-hook, ring or other hanging means to do cable support. In addition to the specialized design, do not use ceiling tiles, brackets and supports to fix the cable, and can not tie the communication cable with the power cable to fix the communication cable.

11. Cable to Desktop

The final part of the network connection may include wiring in office furniture, in the house or under the rug. The final line of cable access to the permanent building inside the network of the switch may be a potential weak link in the network.

12. Network sockets

At the end of each network is a socket, the user can use the jumper to connect the device and the network together. The position, quality and fixed hardware of the socket are very important in the network design. CENELECprEN50174 and eia/tia569 standards for the installation of the wall, floor and furniture in the position of the sockets are relevant provisions. In addition to the principles set out in the standard, the convenience of insertion should also be fully considered.

13. Wiring Frame

In a reliable network that does not change, there is no need to use a wiring rack. In fact, every network is constantly changing, it is the wiring racks can make people faster and easier to achieve network changes. Wiring racks also make it easier to find and troubleshoot errors in the network.

Investment costs

The total investment cost of the network owner is a key factor in determining the installation and supply of bids for the network. Because the cabling network has a service life of at least 15 years, the operating cost and upgrade cost of the network will equal or exceed the initial investment amount. After the network is installed, adding, removing and changing the devices connected to the network usually requires a large investment.

1. Temporary cabling options

An alternative to integrated structured cabling system is a temporary wiring system. It has different forms, some of which are also defined as the category of structured wiring, but they cannot be called integrated structured wiring. In a temporary cabling system, different types of wiring components can be used to implement the functions of the system, but may require higher costs and may often lead to communication failures.

2. Compatibility

The maintenance costs of a temporary cabling system are high, as new parts must be purchased from multiple vendors, which requires additional overhead, as well as the risk of incompatibilities between parts.

3. Network failure

Operational failures can be a larger potential problem and are the most difficult to anticipate. Finding bugs in a poorly designed and implemented network is a very difficult and expensive task. Complete line documentation and easy access to cables and connectors can help maintain the work in a smooth way.

4. Quality Assurance

The quality of the network warranty is the best guarantee that the system failure will not cause accidental loss. Ideally, the cable wiring system and all its components should have a shelf life of 15 years. The design and implementation of the network shall be carried out by a company authorized by the manufacturer, and the parts used shall have no doubt as to its quality assurance. Such projects will be much less likely to have problems in the future.