Discussion on fire electrical design of the hottes

2022-08-24
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Brief discussion on building fire protection electrical design

Abstract: This paper puts forward some views on the use of fire protection specifications in building electrical design, fire power supply and distribution system, grounding and lightning protection, as well as the electrical design of fire control room shared by all systems in intelligent buildings

key words: building electrical design fire electrical design in high-rise and complex multi-storey civil buildings, a perfect fire electrical design system is very important for the timely and reliable operation of various fire electrical equipment in the building after a fire, the effective evacuation of people, materials and the control of the spread of the fire. Here are some personal experiences about this. 1、 The correct implementation of national fire protection electrical design code, design specifications, procedures and other engineering standards is an important basis for electrical design and a technical criterion that should be strictly followed. 1. The classification of standards can be divided into national standards, local standards and industrial standards according to the scope of application of the standards. Local standards and industrial standards are the decomposition of national standards. The national standard code is gb50xxx-yyyy, the local standard code is bxxx, and the industry standard code is the abbreviation of the Chinese phonetic alphabet of the industry. For example, JGJ is the standard of the Ministry of construction and GA is the standard of the Ministry of public security. According to the mandatory standards, they can be divided into mandatory standards and recommended standards. Mandatory standards are the standards that must be implemented. It puts forward the minimum requirements that must be followed. Industrial standards and local standards can be higher than national standards, but not lower than national standards. Recommendable standard is to add the word "t" to the standard code. As the name suggests, it is recommendable and not mandatory. In addition, the standards issued by the International Electrotechnical Commission (IEC) are a wealth of knowledge shared by the international community. After China's accession to the WTO, which is an important method for the current search engine to give the ranking of query results, China has a lot of testing contents such as adding acid and oil to detect evaporation residues, and many electrical specifications have adopted the relevant provisions of IEC standards, which is conducive to the communication with foreign electrical design requirements. 2. Coordination of the relationship between various standards in the actual engineering fire electrical design, sometimes we will encounter the phenomenon that national, industrial and local standards cross each other on the same thing, and the specified technical measures and requirements are inconsistent. Therefore, it is very important to correctly understand and implement standards and carefully coordinate the relationship between them. It is not necessarily appropriate to simply use national standards to govern local standards, or industrial standards are higher than national standards, or later issued standards are better than those issued first. Specific problems should be analyzed and solved appropriately. For example, on the selection of fire detectors in garage, the code for design of automatic fire alarm system (GB 50116-98) and the code for electrical design of civil buildings (JGJ/T 16-92) clearly stipulate that temperature detectors should be used in the form of independent clauses. Over the past few years, many designers have put forward opinions to the relevant departments that it is more appropriate to use smoke detectors, which not only saves investment, but also is conducive to the early detection of fires. In the article 9.0.7 of code for fire protection design of garage, repair garage and parking lot (GB), it is pointed out that smoke alarm facilities can be used in garages with good ventilation conditions, and temperature alarm facilities can be used in general garages. Therefore, you can choose according to specific problems. Another example is that the fire hydrant pump in the basement should be equipped with leakage protection according to the general requirements of the electrical code because it is in a wet place. According to the code for electrical design of civil buildings, leakage protectors that cut off circuits should not be installed for distribution lines whose sudden power failure will cause greater losses than those caused by leakage or overload. If the design is wrong, when a fire occurs, the fire pump may be suddenly cut off due to leakage, resulting in the paralysis of some fire-fighting facilities, which will seriously affect the fire-fighting. 2、 Fully ensure the autonomy of the fire power supply and distribution system. 1. The fire power supply should be at the highest power supply level. Article 24.9.2 of the code for electrical design of civil buildings stipulates: "when the building is powered by high voltage, it is advisable to separate the self formed power supply system from the low-voltage outlet of the transformer, that is, to form a disaster prevention power supply system independently." The power supply load level of the fire protection system power supply, not to mention how to maintain the project power supply system, should be at the highest power supply level. The self-contained power supply system is to ensure the reliability of fire power supply. 2. The product is applicable to the physical properties of metal, non-metal, composite materials and products, such as stretching, tightening, bending, shearing, tearing, peeling, etc. the fire distribution should be independent with a reliable power supply, while the distribution line of the fire equipment is unreliable, which still cannot ensure the safe power supply of the fire equipment. Article 9.1.3 of the code for fire protection design of high rise civil buildings (GB) stipulates that "special power supply circuit shall be used for electrical equipment for fire protection." the power supply circuit specified in this article refers to the power supply circuit from the low-voltage main distribution room (including the distribution room) to the last level distribution box, which shall be strictly separated from the general distribution line. However, in some designs, attention is often paid to the power supply reliability of the section from the distribution room to the distribution box in the fire control room, The reliability of power supply of fire-fighting electrical equipment on each floor, such as electric fire doors, smoke exhaust valves, etc., was ignored, and a special independent fire-fighting system was not formed. For example, there are two elevators in a building, and one of them is a fire elevator according to the requirements of the specification. As required, there should be two ways of power supply into the fire elevator machine room, and one way into the ordinary elevator machine room. But in the design, some designers often share the power supply between the fire elevator and the ordinary elevator in order to save trouble, which is inconsistent with the fire code. The connection of ordinary elevators will inevitably affect the reliability of fire elevators. Undoubtedly, it brings certain hidden dangers to the safety of these circuits. Once these devices fail and cause a short circuit, the reliability of the two power supplies will be affected. 3、 Set ATS and UPS as required. 1. The setting of terminal ATS, automatic fire alarm, fire communication, and other fire electrical equipment are equipped with emergency power supply. In case of power failure of the used power supply, the important load whose power supply is stopped is switched to another power supply by automatic power supply switching device (ATS). Article 9.1.2 of the code for fire protection design of high rise civil buildings stipulates: "the power supply of the fire control room, fire pump, fire elevator, smoke control and smoke exhaust fan of high-rise buildings shall be equipped with automatic switching device at the last level of distribution box." ATS is set at the starting end (such as at the first level of low-voltage distribution in the substation) compared with the end, when ATS is set at the end, in addition to the automatic switching of power failure and power failure, when the power distribution equipment fails or the low-voltage line fails and power failure occurs, the end ATS can also

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