In the high-rise and relatively complex multi-storey civil buildings, the perfect fire-fighting electrical design system can enable various fire-fighting electrical equipment in the building to operate in a timely and reliable manner after a fire, effectively evacuating personnel, materials and controlling the spread of fire. It is very important. Here are some personal experiences.
First, the correct implementation of national fire electrical design specifications design specifications, procedures and other engineering standards is an important basis for electrical design, is to strictly comply with the implementation of the technical guidelines.
1. The classification of standards can be divided into national standards, local standards and industry standards according to the applicable scope of the standards. Local standards and industry 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 in the industry. For example, JGJ is the standard of the Ministry of Construction, and GA is the standard of the Ministry of Public Security.
Mandatory according to the standard can be divided into mandatory standards and recommended standards. Mandatory standards are standards that must be enforced. They set minimum requirements that must be followed, while industry and local standards can be higher than national standards, but not lower than national standards. The recommended standard is to add the T word to the standard code. As the name implies, it is recommended 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, many electrical regulations in China have adopted the relevant provisions of the IEC standard, which is conducive to communication with foreign electrical design requirements.
2. Coordination of the relationship between the various standards In the actual engineering fire-fighting electrical design, sometimes the phenomenon that the national, industrial, and local standards cross each other and the technical measures and requirements specified are inconsistent in the same thing. Therefore, it is very important to understand and enforce the standards correctly and to carefully coordinate the relationship between them. It is not necessarily appropriate to simply rely on national standards to control local standards, or industry standards are higher than national standards, or post-release standards that are superior to the first-issued standards, and should be specifically analyzed and properly resolved.
For example, in the selection of garage fire detectors, the "Code for Design of Automatic Fire Alarm System" (GB 50116-98) and "Code for Electrical Design of Civil Buildings" (JGJ/T 16-92) are clearly defined by independent clauses. It is recommended to use a temperature detector. In the past few years, many designers have advised relevant departments that it is more appropriate to use smoke detectors, which not only saves investment but also facilitates early detection of fire. The provisions of Section 9.0.7 of "Code for Fire Protection in Auto Garage, Repair Garage, and Parking Lots" (GB 50067-97) indicate that smoke alarm facilities can be used in garages with better ventilation conditions. A temperature alarm facility can be used in the library. Therefore, you can choose according to the specific problem.
Another example is the underground fire hydrant pump. Because it is in a humid place, it should be provided with leakage protection according to the general requirements of electrical codes. According to the "Code for Electrical Design of Civil Buildings", the leakage protection device that cuts off the circuit should not be installed for a power distribution line that is more likely to cause a loss due to leakage or overload due to sudden power failure. If the design is wrong, when the fire pump is running, the power leakage may be suddenly cut off, which may cause some fire facilities to be paralyzed, which seriously affects the fire extinguishing.
Second, fully guarantee the autonomy of fire-fighting power supply and distribution system 1. Fire-fighting power supply should be at the highest level of power supply. "Article 24.9.2 of the Code for Electrical Design of Civil Buildings: "Fire, fire and other disaster prevention systems use electricity, when When the building is under high voltage, it should be separated from the low voltage outlet of the transformer to form a self-contained power supply system, that is, the disaster prevention power supply system is formed independently.†The power supply load level of the fire protection system power supply should be at the highest power supply level in the power supply system of the project. The power supply system is to ensure the reliability of fire power supply.
2. Fire-fighting power distribution should have independence. There is a reliable power supply, and the distribution lines of fire-fighting equipment are not reliable, and the safe power supply of fire-fighting equipment cannot be guaranteed. Article 9.1.3 of the "Code for Fire Protection Design of High-rise Civil Buildings" (GB 50045-95) stipulates: "Fire-fighting electrical equipment shall adopt a special power supply circuit," the power supply circuit specified in this Article refers to the low-voltage total power distribution room. (including the distribution of electricity room) to the last level of distribution box, and the general distribution line should be strictly separated, but in some designs, it is often noted from the distribution room to the fire control room distribution box The reliability of power supply, while ignoring the reliability of power supply of fire-fighting equipment in various layers, such as electric fire doors, smoke exhaust valves, etc., does not form a separate system for fire protection.
For example, two elevators are installed in a building, and one of them is required to be a fire elevator according to the specifications. According to the requirements, there should be two power sources introduced into the fire elevator room, and all the way into the ordinary elevator machine room. However, 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 access 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, causing a short circuit, the reliability of the two power supplies must be compromised.
Third, set ATS and UPS as required
1. The setting of the end ATS is equipped with emergency power supply for automatic fire alarm, fire communication, and other fire-fighting equipment. When the power failure is used, the important load that is stopped from being powered is switched to another power source by the automatic power switching device (ATS). Article 9.1.2 of the "Code for Fire Protection Design of High-rise Civil Buildings" stipulates: "The power supply for fire control room, fire pump, fire elevator, smoke exhaust fan, etc. of high-rise buildings shall be at the last level of distribution box. Set the automatic switching device." ATS is set at the starting end (such as the first-level power distribution at the low voltage of the substation). When the ATS is set at the end compared with the terminal, the power is automatically switched except for the power failure. When the equipment fails or the power fails on the low-voltage line, the terminal ATS can also operate, which increases the reliability of the load. When the ATS is set, if the power distribution equipment or the low-voltage line fails and the power fails, the ATS does not operate. There is no guarantee that the load will continue to supply power, so the end ATS is more reliable than the ATS. In some designs, the automatic switching device is not located in the last-level distribution box. After the dual-supply line enters the building, the automatic distribution device is set at the main distribution box, and then the single-circuit to the fire-distribution distribution box at each floor. Obviously this design is not up to standard.
2, computer power should be set to UPS
In addition, the AC power supply of the CRT (cathode ray tube display device) display, fire communication equipment, computer management system, etc. in the automatic fire alarm system should be powered by the UPS device. For the computer power load, if the power supply is suddenly interrupted during use, the information in the computer will disappear. The "Code for Electrical Design of Civil Buildings" stipulates: "When the power load is allowed to be interrupted within 1.5s, it should be set. Intermittent power supply unit." When using ATS to switch between two power sources, there must be a power outage time, which is 0.2-0.3s at the earliest, and the UPS can only be maintained for a short time, and it cannot replace ATS. Therefore, for the power supply mode of the computer power load in the fire protection system, the two power supply settings end ATS plus UPS.
4. Grounding of fire-fighting weak current system 1. Grounding of fire control room To ensure personal safety and reliability of power supply, more and more electronic devices in modern intelligent buildings require a complete and reliable grounding system. Therefore, in the electrical design of high-rise buildings, the design of the grounding system occupies a very important position.
The fire automatic alarm system and linkage control equipment need to set DC working ground. According to the requirements of “Fire Automatic Alarm System Design Specificationâ€, special grounding or common grounding device can be used. Generally, special grounding is used as much as possible, but it is difficult to meet the spacing requirements. The various electrical equipment in the building often uses a common grounding. When the common grounding device is used in the design, it should be noted that the lead-in section of the grounding trunk cannot be used with flat steel or bare copper bars to avoid direct contact between the grounding trunk and lightning protection grounding, reinforced concrete walls, etc., which affects the grounding effect of fire-fighting electronic equipment.
2. Fire-fighting weak current system should be equipped with lightning protection. The lightning protection design of the building is also very important. According to statistics in recent years, the damage of information systems caused by lightning is on the rise. The National Standard 2000 Edition "Lightning Protection Design Code for Buildings" (GB50057-94) newly added the "Lightning Protection Electromagnetic Pulse" section on the original basis, defining computers, communication equipment and control systems as information systems, and automatic fire alarm systems. And fire communication, etc. fall into this category.
V. Problems in the use of fire control room in intelligent buildings 1. Relationship between fire monitoring system and other systems in intelligent buildings In 2000, the state issued the recommended national standard "Intelligent Building Design Standards" (GB/T50314-2000). Building intelligence is on the platform of architecture, consisting of three major systems: Building Equipment Automation System (BAS), Office Automation System (OAS) and Communication Network System (CAS). The BAS consists of three subsystems: building equipment monitoring system, fire monitoring system and safety precaution system, commonly known as BA, FA, SA; the fire monitoring system can operate independently in the building, in addition to the completion of fire information collection, In addition to processing, judging and implementing linkage control, it should also have an interface to communicate with other systems or to transmit remote information. The fire monitoring system can make full use of the intelligent hardware and software resources of the intelligent building to realize network communication, and provide information for the city fire dispatching command center and the urban integrated management network and share the fire protection system with other city management centers.
2, fire monitoring system and other systems combined with the control room should pay attention to the problem in the fire code, the fire control room should be set separately, but there are some high-rise buildings, BA, SA, FA system combined control room, mainly for system integration And management to improve work efficiency. At the same time, SA can be used as an auxiliary monitoring system of FA. When the fire automatic alarm system sends out an alarm signal, the on-duty personnel can confirm the actual situation of the fire scene through the camera lens of the security system, and take further measures. However, the electrical design of the control room should pay attention to the following problems:
(1). The BA system can only provide monitoring for the FA system, it cannot be controlled, and the independence of the FA must be maintained.
(2). The independence of the working ground at each different operating frequency should be fully considered in the grounding design of each system.
(3). Strictly prevent electromagnetic field interference to various systems.
In short, the above is only a brief view of the electrical design of building fire protection. In actual engineering, only the understanding and implementation of the specifications are carefully understood, which truly reflects the characteristics of the people-oriented building, and makes the design of fire-fighting electrical more perfect.
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