Hello everyone, I'm Brother Xue. 220V50Hz and below are collectively referred to as weak current, which mainly provides people with power energy and converts electrical energy into other energy sources, such as air conditioning electricity, lighting electricity, power electricity and so on. Weak current system has a wide range, more common: security monitoring system, fire alarm system, entrance and exit control system, parking lot charge management system and building automatic control system, etc., today to talk about the installation process and construction specifications of weak current engineering.
I. Construction Steps:
1. Survey the site
A. Negotiate with the customer to borrow the material room where the materials are stored, and the material room should be large enough and close to the construction site. B. Hydropower equipment. Whether the site has the necessary water and electricity facilities for construction. C. Electrical load. Whether the power line at the construction site can match the load requirements of the project. D. Device layout. Determine the location of the cabinet, the installation location of the terminal equipment, and the routing path of the line. E. Sample specifications. Clarify the customer's requirements, determine the model and style of the sample. To form a document, the customer signs and acknowledges. F. Security. Safety of raw materials, fire and theft prevention measures at the construction site.
2. Draw the network topology diagram and layout diagram, and submit it to the customer for confirmation.
3. Formulate the project schedule. List the tasks that need to be completed during the construction period, as well as the order in which each work is completed, and determine the detailed planning time, as shown in the figure below. After the completion of the project schedule, a copy should be handed over to the customer for the customer's supervision and cooperation.
4. Designate the person in charge of the project and the project supervision personnel, responsible for planning and preparation, preparation, user cooperation requirements, etc., put forward the timetable for the cooperation of various departments, and be responsible for internal and external coordination and construction organization and management
5. On-site construction, record the construction progress every day, and adjust the plan in time according to the completion of the plan to ensure that the project is delivered according to the requirements of the construction period.
6. On-site certification test, make test report, print IP address table, routing table, configuration table.
7. Acceptance. The documents established and perfected in the above links are handed over to the customer as part of the acceptance data. At the same time, the company should also retain the page book as customer information for after-sales service.
II. Layout Specification:
The layout is the basis for subsequent work, so it must be determined beforehand, otherwise it will be extremely costly to rework. The height specification of the computer desk: about 70CM in primary school, about 75CM in middle school; SEAT SIZE SPECIFICATION: WIDTH 60-80CM, FRONT AND REAR ABOUT 60CM; Reserved width of aisles between rows and columns: 60-100CM; The layout drawing must be drawn according to the actual size of the site and facilities, and the detailed dimensions should be indicated in the drawing. Determine the layout plan to sign and confirm to the customer, and if necessary, outline the layout on the site to get an intuitive feeling.
3. Wiring specifications (network cable, power line)
1. Cable mark content: on the sheath of the cable, indicate the name or code of the manufacturer and the cable model specification, manufacturing year, cable length, and the cable length at intervals of about 1M.
2. The specifications of plastic trunking and its accessories should meet the design requirements, and the corresponding stereotyped products should be selected. The ambient temperature of the laying site shall not be lower than -15 degrees Celsius, and its flame retardant performance oxygen index shall not be less than 27%. The inside and outside of the trunking should be smooth and free of edges, there should be no distortion, warping and other deformation phenomena, and there should be a product certificate.
3. There should be redundancy when the cable is deployed. At the cabinet, the length of twisted pair cable is reserved, generally 3~6m; The terminal is 0.3~0.6m; The length reserved for optical cables at the equipment end is generally 5~10m; If there are special requirements, the length should be reserved according to the design requirements
4. When laying the movable floor in the equipment room, the plate is laid tightly and firmly, the allowable deviation per square meter should not be greater than 2mm, the floor pillars are firm, and the grounding of the movable floor anti-static measures should meet the design and product description requirements.
5. Each pair of twisted wires should be kept twisted as much as possible, and the non-twisted length should not be greater than 13mm.
6. The sheath shall not be scratched by peeling off the insulation layer, and should be peeled off with special tools.
7. There shall be no joint phenomenon in the middle of the cable.
8. The longest line spacing of twisted pair is 100 meters, and the twisted pair repeater connection can be extended by more than 100 meters, and the data of repeaters in each section of line cannot be more than three.
9. Optical fiber transmission distance: transmission rate 1Gb/s, 850nm, ordinary 50μm multimode fiber transmission distance 550m, ordinary 62.5μm multimode fiber transmission distance 275m, new 50μm multimode fiber transmission distance 1100m.
10. The bending radius of the cable should comply with the following regulations:
a The bending radius of unshielded 4-pair twisted pair cable should be at least 4 times the outer diameter of the cable, and at least 8 times during the construction process.
b The bending radius of shielded twisted pair cable should be at least 6~10 times the outer diameter of the cable.
c The bending radius of the trunk twisted pair cable should be at least 10 times the outer diameter of the cable.
d The bending radius of the optical cable shall be at least 1.5 times the outer diameter of the optical cable and at least 20 times during the construction process.
11. When the twisted wire is connected in the information socket (RJ45), it must be snapped according to the color scale and wire pairing order. The type, color scale and number of the socket should comply with the provisions of T568A and T568B. As shown in the following figure.
12. When making the crystal head, the outer protective layer of the cable needs to be pressed into the connector and not outside the joint. Because when the cable is pulled by the outside world, it is the entire cable that is stressed, otherwise it is the metal part of the cable and the connector that is connected.
13. When the twisted pair cable and the wiring module (IDC, RJ45) are snapped, it should be operated according to the design and manufacturer's regulations.
14. The shielding layer of the shielded twisted pair cable is in reliable contact with the shielding cover at the terminal of the connector, and the cable shielding layer should be in contact with the 360o circumference of the connector shielding cover, and the contact length should not be less than 100mm.
15. The two ends of each double glue line should be glued and numbered to facilitate installation and maintenance.
16. Provide reliable construction power supply and grounding device in the handover room and equipment room.
17. The temporary power supply at the construction site should have a complete plug. Switch. Receptacle. Leakage protector setting, temporary power must use cables. The power cord comes in three colors: Firewire Red. Zero line blue. Ground line yellow. All unidirectional sockets should be connected "Left Zero Right Fire Middle Ground" or "Upper Fire Zero Bottom".
18. When the power cord pipe passes under the ground, it must be connected tightly with the casing, and no joints are allowed under the ground, and elbows must be applied to enter and exit the ground. Before the ground is not closed, the PVC casing must be protected, no cracking damage is allowed, the PVC casing should be covered when laying floor tiles, and when nailing the wooden floor, the power cord should be laid along the corner of the wall to prevent the power line from being damaged by nails.
19. The power cord should be straight and horizontal, not diagonally pulled to prevent it from being hammered. Nail damage.
20. All kinds of strong and weak electrical socket interfaces should be as few as possible. All sockets. THE SWITCH SHOULD BE MORE THAN 300MM ABOVE THE GROUND, AND IT WILL NOT BE OBSCURED BY SLIDING DOORS AND FURNITURE.
21. Weak current lines and strong current lines are not allowed to share a tube, and the separation distance is more than 0.5m.
22. Three-phase five-wire system refers to A, B, C, N and PE lines, of which PE line is a protective ground wire, also called a safety line, which is specially used to connect to equipment shells to ensure the safety of electricity. It is best to use standard/normative wire colors in the application: yellow for A wire, blue for B wire, red for C wire, brown for N wire, and yellow-green for PE wire.
23. The power supply between the various plates in the project should be controlled separately as much as possible, and the power supply should be independent as much as possible, and each other should not worry about each other.
4. Equipment installation and commissioning
1. Selection specification of cabinet placement location
A. Security. Concealed, ventilated, preferably with a dedicated room, with restricted access. B. Reliability. There is a suitable power access point, sufficient power guarantee, easy maintenance. C. Availability. The line spacing to each terminal is within the range required by the specification. D. Economy. The total amount of line spacing to the terminal is minimal.
2. Installation specifications for network equipment
A. Network equipment (routers, switches, etc.) should be installed on fixed bays; B. The fixed bracket should generally be more than 500mm from the ground; C. The cable inserted into the network device should be fixed to the bracket or wall to prevent it from falling off inadvertently.
3. Terminal equipment installation steps
A. First read the equipment manual and equipment installation manual. B. The equipment should be counted according to the packing list, the appearance of the equipment should be checked, and the records should be made carefully and in detail. C. The device is in place. D. Power up each device separately and do a good job of self-test. E. Connect each device to the server for online inspection, and problems should be solved one by one. The faulty equipment is left to solve last. F. Install the system software and carry out the joint debugging of the main system. G. Install the software of each workstation, and each workstation can work on the Internet normally. H. Solve all remaining problems one by one. I. Users can check on the machine at will according to the operating procedures, and are familiar with the various functions of the network system. J. Trial run begins.
5. Troubleshooting specifications for weak current projects
1. According to statistics, about 50% to 70% of weak current engineering failures are related to cables. Therefore, the quality of the cable itself and the quality of installation directly affect the normal operation of the network. There are many types of network cable faults, which can be summarized into two categories: physical faults (also known as connection failures) and electrical performance failures.
A. Physical failure. Physical faults mainly refer to directly observable faults caused by subjective factors, mostly caused by construction processes or accidental damage to network cables, such as: wrong line sequence of modules and connectors, open circuit, short circuit, ultra-long link, etc.
B. Electrical performance failure. Electrical performance failure mainly refers to the electrical performance index of the link does not meet the requirements of the test standard, that is, the cable does not meet the design requirements during signal transmission. In addition to the quality of the cable material itself, the factors affecting electrical performance include excessive bending of the cable during construction, too tight cable binding, excessive stretching and excessive proximity to interference sources, such as: near-end crosstalk, attenuation, return loss, etc.
2. The fault of integrated wiring is mostly in the horizontal area. There are many threading and module terminations here, the construction process varies from person to person, and the building pattern is more complex than the vertical part. In general, there are three aspects that cause failure.
A. The electrical performance of the product itself, that is, the design and production quality of the product. B. The design of the engineering scheme, according to the architectural pattern, the design requirements of the wiring system. C. Construction process, which is the embodiment of the overall quality of wiring, good products and good construction plans, must have good construction completion.
3. Common mistakes of tying wires. Common errors in wire typing are open circuit, short circuit, reverse connection (two of the lines in a pair are crossed, such as 1 for 2, 2 for 1). Another error is jumping, such as 1, 2 corresponding to 3, 6. There are two main reasons for this error. First, one end of the cable uses the T568A standard, while the other end of the cable uses the T568B standard. Second, in the practical application of the network, it is sometimes necessary to use this jumper. When some switches cascade with the switch, jumper cables are required.
In addition, when connecting the PC to the PC (without going through the switch), jumper cables are also required. Some users can also access the Internet when using jumper cables, and can also cascade the switch when using the correct wiring. This is because the switch they use is a smart switch. This type of switch automatically reverses the wiring around the alignment. But that doesn't mean this way of tying the line is correct.
Finally, there is a mistake that is cross-winding. Usually the reason for this result is that 1 and 2 are a pair, 3 and 4 are a pair, 5 and 6 are a pair, and 7 and 8 are a pair. The network uses 1, 2 and 3 and 6 instead of 3 and 4 for communication. This faulty wiring cannot be checked with an eye or a multimeter because end-to-end connectivity is normal. The biggest harm of this incorrect wiring is that it will produce a lot of near-end crosstalk. It does not cause the network to be disconnected, but makes the network run very slowly, intermittently. It is a soft fault and is cumbersome to check when the network is running. [Brother Xue warm tips: crystal head reserve = information points * 2 * 20% Network cable measurement estimate: (shortest line spacing + longest line spacing) ÷2×1.1× total number of information points Standard length of network cable per box: 305±5 meters]
Introduction to the latest quality information
This set of weak current data summarizes a large number of technical documents, 313 PPT schemes, 279 standard specifications, 60 design schemes, 119 drawing materials, 8 sets of construction drawings, 20 sets of bills of quantities, 20 construction organization designs, 69 visio topology diagrams and blocks, 54 excel tables, complete construction process documents and acceptance documents, etc., very comprehensive.