Design and application of the fire alarm system fo

Design and application of leakage fire alarm system

with the substantial increase of social power consumption, the fire accidents caused by electricity increase sharply. Electric leakage not only threatens personal safety and causes property losses, but also is the main hidden danger of fire in various buildings. Among the top ten fires in 2005, the catastrophic fire in Liaoyuan Central Hospital of Jilin Province and the catastrophic fire in Shantou South China hotel with a large number of deaths were all electrical fires. According to the statistics of the Ministry of public security, of the 100836 major fires in China in January, 2005, 30512 fires were caused by violating the regulations on electrical installation and use, accounting for 30.3% of the total fires in the same period. The occurrence rate of electrical fires ranked first among all kinds of fires. In order to contain electrical fire accidents, relevant departments have attached great importance to it, successively formulated and modified relevant national standards and specifications, emphasized the protective role of leakage fire alarm system in preventing electrical fires caused by grounding faults, and required to set leakage fire alarm system in buildings. With the gradual improvement of national standards and specifications, the setting of leakage fire alarm system will be more and more extensive. At present, there are few technicians who are familiar with the design and construction of this new alarm system, and the relevant technical specification system is not perfect. In practical application, the specifications are implemented according to different understandings and understandings, resulting in confusion in design and application. The author discusses the understanding and practical application of leakage fire alarm system design, and discusses with peers

2 design basis of electric leakage fire alarm system

2.1 provisions of relevant specifications for setting electric leakage fire alarm system

(1) article 9.5.1 of partial revision of code for fire protection design of high rise civil buildings GB50045-95 (2005 Edition) (hereinafter referred to as "the high standard"): electric leakage fire alarm system should be set in places with high fire risk and dense personnel in high-rise buildings

(2) article 11.2.7 of code for fire protection design of buildings GB (hereinafter referred to as "building code"): Class B and class C plants and class C warehouses that supply power according to class I load and whose building height is greater than 50.0m; Power plants (warehouses) that supply power according to class II load and the outdoor fire water consumption is greater than 30l/s; Theatres, cinemas, shops, exhibition halls, radio and television buildings, telecommunications buildings, finance, trade and finance buildings and other public buildings with outdoor fire water consumption greater than 25l/s supplied by secondary load; The key ancient buildings of brick and wood structure in the national level cultural relics protection unit for judging the fracture type; Residual current operated electrical fire monitoring system should be set for fire protection electrical equipment powered by class I and II loads

(3) item 7 in article 6.5.2 of code for design of residential buildings (GB 50096-1999) (2003 Edition): the main power incoming circuit breaker of each residential building shall have leakage protection function

(4) requirements and detection methods for building electrical fire prevention (at the end of October, 2004, the mandatory standard has passed the review and is being submitted for approval). The relevant article clearly requires that "in order to prevent leakage fire of electrical equipment and lines, residual current action protectors that automatically cut off the power supply or alarm shall be set at the incoming end of the power supply"

(5) installation and operation of residual current operated protective devices (GB) clearly states that: "buildings and residences of enterprises and institutions shall adopt hierarchical protection, and the residual current protective devices at the power supply end of buildings shall meet the functional requirements of electrical fire prevention." For "urban power distribution, residual current protection devices against electrical fire shall also be considered when hierarchical protection is adopted in power users." Can you operate the bending testing machine in the introduction, 3.26 in terms and definitions, 4.4.5 in graded protection, etc. of the standard? The function of installing residual current protection device to prevent electrical fire caused by grounding fault is emphasized, and the installation of residual current operated fire monitoring device and action parameters in the building are clearly specified. The model diagram of installing residual current operated fire monitoring device is provided in the appendix

2.2 understanding of relevant specification provisions

2.2.1 definition of leakage fire alarm system

installation and operation of residual current operated protective devices gb1395 these mechanisms are all enclosed in the steel plate inner shell for definition, "residual current operated electrical fire monitoring system": used to monitor residual current transformers, residual current detectors It is a device composed of an alarm or a controller for real-time monitoring of electrical fire and giving an alarm or cutting off the power supply. The leakage fire alarm system required by the relevant provisions of the high standard is the "residual current operated electrical fire monitoring system" defined in the GB installation and operation of residual current operated protective devices. The general term of "leakage" in the world is "residual current", and other relevant national standards are also called "residual current". Therefore, new standards such as the construction plan uniformly call "leakage fire alarm system" as "residual current operated electrical fire monitoring system". The leakage fire alarm system is a digital monitoring network system based on computer technology, which is responsible for monitoring the electrical fault of the terminal and realizing the functions of remote transmission, remote control and alarm display. Both the high standard and the construction standard emphasize that "qualified products tested by the national fire electronic product quality supervision and inspection center shall be adopted to ensure quality safety". "Leakage fire alarm system" itself is a connected integrated device and a complete system, which should meet the requirements of the electrical fire monitoring system GB, rather than a single leakage current alarm or traditional leakage switch set up in the past

2.2.2 understanding of "should" for setting leakage fire alarm system

the specification wording notes indicate that "should" means that a little choice is allowed, and it should be done first when conditions permit. It can be seen that "should" in principle requires the first consideration. In the absence of special conditions, Judith hackitt, who should be the Minister of health and safety of the UK recently, has accepted the appointment and selection setting of the UK government. In the review of building fire protection design, the setting requirements of leakage fire alarm system should be emphasized

2.2.3 understanding of setting places

the author believes that it should be emphasized that buildings with "densely populated places" as the main body, or public buildings with large area, complex functions and important properties, should be equipped with leakage fire alarm system, and electrical devices or places that will cause significant economic losses and adverse social impacts due to power outage must also be considered. In principle, residence design requires that leakage fire alarm devices should be set on the main power incoming line of each residence. If conditions permit, a system should be formed, and the signals should be fed back to the fire control room, duty room, property management room, etc. to realize centralized alarm. In the design of public buildings, residual current protection devices shall be set according to the requirements of code for design of low voltage power distribution, and the important circuits therein shall be subject to systematic detection and control. The provisions of the high level planning on the location are relatively simple and poor in operability. The provisions of the construction planning are more detailed and easier to implement