What problems should be paid attention to in weak current design?

In a sense, design is the foundation of the success or failure of the project, and it is a very important and challenging work, especially an excellent weak current design. However, the current situation of weak current design in China is not optimistic. I think the main reasons are: (1) There are many subsystems of weak current system, involving many high and new technologies, the existing theoretical system and norms are not perfect, some key issues are still inconclusive, and there are few successful engineering construction experiences worth learning and popularizing. These are the objective reasons for the difficulty of weak current design. (2) The lack of excellent designers and the urgent need to improve the quality of designers are human factors. At present, some weak current designers are often behind closed doors, seriously divorced from reality and user needs, blindly pursuing high standards and high grades, and their designs are the same, with no features and new ideas, which has caused many weak current projects to be "born with defects". The high-tech and complexity of weak current require designers (especially chief designers) to have high quality. He has extensive professional knowledge, rich design experience and skills in computer, communication, electricity, water and heating, and has keen foresight for new technologies. (3) Unlike other civil and plumbing majors, weak current design is easily restricted by other majors and units in practical engineering, which is determined by the nature of the major. For example, the design can only be fully developed in the later stage of the project, which leads to tight design time and no time to think carefully; In the implementation of the project, the bidding behavior is standardized and the system products are changed at will, resulting in a lot of waste of design work; The construction drawing is seriously out of touch with the decoration, and the user's requirements are inappropriate and unclear, which makes the designer do a lot of useless work; User functions change at any time, which brings a lot of inconvenience to the design. (4) People (including many owners, government departments, some Grade A design institutes, large-scale construction units, supervision units and engineering companies) have misunderstandings about the whole weak current design, and they are not very clear about the design procedures, processes and contents. In the whole design "baton", there are differences among designers, and the design division of labor is not reasonable. To sum up, in order to improve the quality of weak current design, in addition to long-term efforts to increase the investment of the whole industry, actively promote the in-depth theoretical research of weak current specialty, and actively cultivate high-quality design talents through various channels (especially universities), another very important and effective method is to change ideas, straighten out the whole construction workflow, and strengthen publicity and standardization. Let people know clearly the procedure, process and content of weak current design from chaos, and fully ensure the consistency of designers' quality, so as to change the passive situation of "no rules, no Fiona Fang" in weak current design. Only when everyone understands and abides by the rules and procedures can the design move towards standardization. Then, what steps and contents should a typical and perfect weak current design include? I think it should include at least four parts: planning and design, overall design, detailed (engineering construction) design and reconstruction and expansion design, and weak current design should run through the whole process of the project. In order to make the design more reasonable, the planning and design of 1 must be well prepared before design. Planning and design is such an important but easily overlooked task, which includes three steps: user demand analysis, planning (preliminary) design scheme and feasibility study. User demand analysis: the designer should first collect the ideas, requirements and problems put forward by users on the weak current system through oral conversation, discussion and analysis with the owner, and define the goals to be achieved by the weak current system. On this basis, the designer combs the user's needs, clarifies and quantifies the requirements for the owner, and forms a scientific, rigorous and operable specific goal, that is, combining the existing products and various related technologies to determine the system goal in terms of function, performance, realization and cost. Planning (preliminary design): On the basis of determining the system objectives, designers should describe and demonstrate the overall scale and performance index of the weak current system, the scale and performance index of each subsystem, the selected technology and how to realize it from a macro perspective around user needs and building functions. Make the user system have an overall concept and understanding, and have a good idea of future implementation and funds. At the same time, it is also a document in the system analysis stage. The planning and design scheme generally includes: the overall overview of the target system, the overall structure of the target system and the description of each subsystem. The description of each subsystem includes: system objectives, system wiring structure, system implementation scheme and system budget. When planning the design scheme, we should pay attention to fully expressing the design intention in illustrated and easy-to-understand language, so that relevant decision makers and technicians can use it as the basis for argumentation and evaluation. Feasibility study: After the planning and design scheme is published, it is necessary to carry out feasibility study, that is, to make a clear judgment on the necessity, technological advancement and economic rationality of weak current system construction. Only in the process of investigation and judgment, it is confirmed that the construction of the system meets the above three requirements, and the next design can be carried out. Necessity of construction 1. 1 Many weak current subsystems have high advantages, but it must be noted that this kind of system can not be selected in all cases, and should be installed in very necessary occasions according to the actual situation of the user department. In a word, different technical schemes are preliminarily determined through investigation, and then the installation of this weak current system can be implemented only when the schemes have obvious advantages. For some occasions where other equipment or methods can be used, this subsystem should not be installed. 1.2 economic rationality economic rationality includes two meanings, one is the selection of equipment and the reasonable investment cost of the project; Second, the input and output of system construction are reasonable. In other words, the construction of this subsystem should be economical, that is, the sum of depreciation and maintenance costs of the system itself is less than the economic benefits obtained by using this system in improving production (work) efficiency, improving product (work) quality and ensuring safety. Of course, the benefits mentioned here refer to the sum of the benefits directly and indirectly created by the system itself. In short, the installation of the system should be carried out after scientific calculation and analysis to determine the economy and rationality. 1.3 advanced technology The design content of system equipment selection and combination mode should pay attention to advanced technology. The so-called advanced technology means that a design scheme can not only meet the requirements of users, but also meet the technical indicators stipulated by the state, and it also has a relatively advanced level at present. At least, the products that have been eliminated at present cannot be selected, but we should not blindly pursue progress. In particular, when selecting imported equipment or introducing complete systems, factors such as China's national conditions, the technical level of user units, the future domestic equipment maintenance capacity and the source of accessories should be considered to prevent the maintenance work from being difficult after the system is put into use. The overall design begins with the overall design, and the designer will determine the implementation scheme of the system according to the user's demand book and planning and design scheme, combined with the actual technical, economic and social conditions. If in the last stage, the designer's main task is to investigate and understand the situation, then the main task from this stage is to weigh the advantages and disadvantages in various technical means and implementation methods, carefully design, and improve the reliability, practicability and expansibility of the system as much as possible. This is a step-by-step detailed design process from the target system to the concrete implementation, which can be divided into two continuous but relatively independent stages: overall design and detailed design. Overall design is the overall planning and design of the target system, and it is the modification, supplement and deepening of the preliminary design, including: system function design, integrated design, logic design, application design, coordination design, process design, environment design, etc. 3 Detailed (engineering construction) design The most important thing in engineering construction design is the system construction drawing design, which is the general name of system technical design and construction drawing design. Usually, the construction drawing design can be carried out after the preliminary design of the system and the design of the project implementation scheme. Engineering construction drawing design is a detailed and comprehensive technical analysis and engineering parameter calculation of software and hardware configuration and system function requirements in the preliminary design and construction scheme of the system, and then the exact technical data is drawn on the construction scheme. In particular, the integrated system needs to put forward detailed requirements and corresponding text descriptions for the installation technology and interfaces of its related subsystems in various professional aspects. Laying, location, size and direction of reserved holes, embedded parts, trunking and bridge required for civil construction. It should also be clearly stipulated in the construction drawing that the national standard general atlas should also be used to draw the construction and installation drawings of all kinds of stereotyped mechanical and electrical equipment products that need systematic monitoring and management, so as to save working hours and speed up the construction progress. The design depth of engineering construction drawing shall meet the following requirements: (1) The positioning and dimensions of reserved holes, embedded parts, trunking and bridge required by civil construction, as well as the requirements of technology and laying. (2) The weak current machine room and weak current well can use common grounding power supply and grounding, and the resistance should not be greater than1ω; When using weak current grounding alone, the grounding resistance should not be greater than 4Ω. (3) The pipelines of relatively unchanged floors (such as equipment floors), some floors and building access networks are embedded. (4) The position, size and layout requirements of the central control room and various weak current computer rooms. (5) Positioning and installation requirements of system field controller (DDC) and monitoring point (IP/OP). (6) System wiring specifications and wiring requirements. (7) The number and mode of system equipment line termination. System engineering construction drawings generally include: drawing catalogue, general construction instructions, system drawings of weak current subsystems, system pipeline plan, layout details of weak current wells and computer rooms, system wiring and termination drawings. Because the weak current system adopts centralized and unified integrated design, it is possible for us to embody the installation and wiring methods of embedded pipes, trunking bridges of each subsystem (except that the fire alarm system needs to be designed separately according to the specifications) and the corresponding equipment positioning in a set of construction drawing design.