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Since the implementation of the “high regulations”, the design, construction, fire protection, owners and other units have different understandings of the new provisions of “high regulations”, but there are great differences in the standard methods of design, construction and acceptance. There is a hidden danger to the normal operation of the electrical fire alarm system. Since the country has not yet introduced design, construction, and acceptance standards, many design, complete sets, and owners have the words "high" and "conformity". Different understanding, the standard provisions are "electrical fire alarm system", indicating that it should be a networked whole device, is a complete system, rather than a single electrical fire monitoring detector or traditional leakage switch that has been dispersed in the past can be competent. In the description of the "High Regulations", special emphasis is also placed on "these equipments should be tested by the National Fire Electronic Products Quality Supervision and Inspection Center to ensure quality and safety". It can be seen that it is not possible to use ordinary leakage switches, many electrical designers There is often a tendency to make this mistake.
Regarding the grasp of the word "Yi", the specification of the wording indicates that it allows a slight choice and should do so when conditions permit. It can be seen that the "suitable" principle is to be considered first. In the absence of special circumstances, it is not possible to choose to cancel the setting without the consent of the fire department.
First, the specific design and installation location of the electrical fire monitoring detector. Because the "high-rise civil building design fire code specification" is the building design specification, not the electrical fire alarm system product inspection standard, it is not the electrical fire alarm system design, construction acceptance specification, therefore, the provisions The requirements are relatively coarse, resulting in the current electrical fire alarm system design, construction, and acceptance are not clearly marked, which will inevitably affect the smooth construction and operation of the electrical fire alarm system project, affecting the normal function of its electrical fire alarm system.
1.1 According to the national standard "Installation and operation of electrical fire monitoring action protection device" GB13955-2005, regarding the classification protection provisions, when installing the electrical fire monitoring fire monitoring device, the reasonable distribution design of the fire prevention area in the building should be made to determine the appropriate The protection range, the scheduled electrical fire monitoring action value and the action time, and should meet the operational characteristics requirements of the hierarchical protection, and reduce the power failure range caused by the failure of the power supply. Therefore, the design should first have a clear understanding of the relevant parameters of the control power distribution system, study the relevant drawings related to the control of the distribution line, and investigate the distribution of the building electrical to determine the distribution equipment (distribution box, disk) The position of the cabinet, the electrical fire monitoring detector is assigned to the corresponding power distribution equipment, according to the actual situation, such as: setting current, normal leakage current estimation, determine the number of electrical fire monitoring detectors. In order to avoid repeated settings, the allocation principle is as follows: According to the building electrical load and the specific conditions of the line, it is determined to adopt the two-level or three-level protection mode; generally all the two-stage switches must be equipped with electrical fire monitoring detectors; Installation should be based on actual conditions of the load and the actual use of the building, fire hazard, etc. After determining the installation position of the electrical fire monitoring detector, it should be designed and wired in the bus mode. The bus system is a four-core cable, and an independent system bus should be formed. The four-core bus is converted into an RS232 serial port by the bus-based transmitter data, and the terminal An electrical fire alarm system consisting of a console (leakage alarm system host). The bus system transmitter and terminal console (leakage alarm system host) should be installed in the fire center or duty room.
1.2 Important load: including fire, security, emergency power supply, channel lighting circuit and important places that are not allowed to be powered off. According to GB139554.6, alarm type electrical fire monitoring detector should be installed, which has the signals of collecting leakage current and over current. When the set value is exceeded, only the sound and light alarm signal is issued, but the power is not cut off, and the collected signal is transmitted to the control center through the bus mode, and the manual power-off mode can be set, which ensures the safety of the power and ensures the safety. Uninterrupted power supply.
1.3 The design must pay attention to the principle of grading protection and avoiding large-scale power outages to prevent electrical fires. GB13955-2005 emphasizes the use of grading protection. The electrical fire monitoring and protection devices on the power supply or branch lines should be connected with the electrical fire monitoring and protection devices at the end. The action characteristics should be coordinated to achieve hierarchical protection with action selectivity to avoid large-scale power outages. Under normal circumstances, the low-sensitivity time-delay electrical fire monitoring and protection device should be used on the power incoming line or branch main circuit. At the end, the leakage current IΔn≤30mA and the rated operation time Tn<0.1s are mainly used to prevent personal electric shock protection and complement the electrical fire alarm system.
One or several electrical fire monitoring detectors may be installed at the main entrance of each floor of the building, but the electrical fire monitoring detectors with appropriate parameters shall be selected and selected according to the normal leakage current. The electrical fire monitoring at the general incoming line is set at 200 to 500 mA.
Second, the installation method of electrical fire monitoring detector According to the selection of electrical fire monitoring detector products and the characteristics of engineering power distribution system, there are generally the following design methods:
2.1 The installation design of the internal form of the distribution box or control box is generally used for the new project. There is a special floor distribution box or control box on the floor. The electrical fire monitoring detector is installed directly in the appropriate position inside the distribution box or control box.
2.2 Installation of the external form of the distribution box or control box (cabinet) The electrical fire monitoring detector is separately made into a box, and the total power is passed through the electrical fire monitoring detector, and the power is connected to the distribution box or control box.
For the application of new and old (reconstruction) projects, the electrical fire monitoring detector only needs to introduce the power supply into the leakage alarm switch device before connecting it to the distribution box or control box.
The fire monitoring box specially installed with the leakage controller is located near the distribution box or control box. The retrofit project recommends the use of rectangular leakage transformers, which can try not to touch the internal wires and device layout of the original distribution box (cabinet).
2.3 Installation design of the distribution cabinet form The leakage controller is embedded directly on the distribution box or the control box panel. Only the current transformer is fixed at the appropriate position in the cabinet (generally at the upper or lower end of the main air), without changing the power distribution. The internal structure of the cabinet does not need to add a separate leakage controller installation box, which is beautiful and does not occupy space. The requirements should be clearly stated in the design. After the construction drawing is completed, the power distribution cabinet complete plant considers the size of the opening of the electrical fire detector embedded in the panel.
3. The following matters should be noted in the installation of electrical fire alarm system.
3.1 Electrical Fire Alarm System Construction Main Unit According to the characteristics of the above-mentioned electrical fire alarm system, the electrical fire alarm system has high independence, but it is inseparable from the power distribution system. It is easier to coordinate and cooperate with the construction of the high-power system.
On the contrary, the practice proves that it is easy to whip the construction of the construction unit of the fire alarm system, and it is difficult to coordinate and cooperate. Moreover, it is unfamiliar with the strong use of the control cabinet. It is unfamiliar to the connection and installation position of the strong electric wires, and the construction quality is difficult to guarantee.
3.2 Construction requirements of electrical fire alarm system National standard "Installation and operation of residual current action protection device" GB13955 Part 6 "Installation of electrical fire monitoring and protection device" clearly states: "Electrical fire monitoring and protection device installation should fully consider the power supply mode, Supply voltage, system grounding type and protection method. The form of electrical fire monitoring and protection device, rated voltage, rated current, short-circuit breaking capacity, rated residual operating current, breaking time should meet the requirements of protected lines and electrical equipment, in different systems. The grounding form should be correctly wired."
3.3 The host of the system can be cyclically controlled with 1,250 electrical fire detectors, and connected to the microcomputer by ordinary telephone line. The microcomputer is connected to the detector via the Rs232 communication port (com1) via the FH bus. When an electrical fault occurs. At the same time, the corresponding extension automatically transmits the alarm information to the system microcomputer. After the microcomputer receives the micro-machine, the alarm information system interface displays the fault type and voice prompt, and the monitoring system roots the alarm information, and the corresponding load electrical circuit diagram can be adjusted. Accurately guide maintenance personnel to handle faults.
4. When the electrical fire alarm system is put into use, the following items should be noted:
4.1 When wiring, it should be correctly wired according to the incoming and outgoing ends of the power supply indicated by the electrical fire monitoring detector, and must not be reversed.
4.2 When installing the molded case circuit breaker, there should be sufficient arcing distance in the direction of arc discharge as required.
4.3 When installing, the N-line and PE lines must be strictly distinguished. The 3P 4-wire or 4P 4-wire N-line should pass the leakage mutual-inductance detector of the electrical fire monitoring system. The N-line of the leakage transformer through the electrical fire alarm system shall not be used as a PE wire. It shall not be grounded repeatedly or the exposed device may be exposed to the conductor. The PE line shall not be connected to the electrical fire monitoring and protection device.
4.4 When the electrical fire alarm system is included in the construction of the power distribution system construction unit, both parties shall fully communicate and coordinate the relevant installation methods, dimensions and electrical technical parameters. When using the electrical and electrical fire alarm system for new projects, when ordering the power distribution cabinet (box), the product should be requested from the manufacturer for the external dimensions and opening dimensions to facilitate the calculation of the installation location.
4.5 "High-rise civil building design fire protection code" GB50045-2005 requirements of 9.1.1, electrical fire alarm system should be implemented in accordance with the provisions of fire-fighting electricity. Therefore, regardless of the terminal console (leakage alarm system host) set up by the fire center, it must be implemented in accordance with the provisions of fire-fighting electricity, and access to fire-fighting electricity.
4.6 Electrical leakage alarm system The leakage current transformer is installed in the power distribution cabinet (box). Pay special attention to the construction safety. It should be constructed in the case of power failure, and pay attention to the separate lines of strong and weak electricity, pay special attention to prevent misconnection or take The line causes the strong electric power to enter the four-core line of the electric fire alarm system and burns the entire electrical fire alarm system.
4.7 Reconstruction Engineering Generally, the electrical fire monitoring detector/electric fire monitoring detector should be placed at the lower end of the molded case circuit breaker. When the installation is inconvenient, consider installing it at the incoming end of the molded case circuit breaker.
4.8 The construction unit shall be equipped with a mobile (handheld portable) electrical fire monitoring detector, and firstly conduct the electrical fire monitoring of the power distribution system during commissioning, and timely eliminate the abnormal situation of electrical fire monitoring, and make detailed records. According to the requirements of 5.7.3 and 5.7.5 of GB13955 standard, set the appropriate leakage current alarm threshold. Usually, the alarm setting value is not less than twice the leakage current value of the line and equipment.
4.9 bus system four core wire in parallel, all electrical fire monitoring detectors are connected, the bus is led to the control center, converted to RS232 serial port by the bus system, connected to the receiving host, the host should be installed with leakage monitoring software, with two-way The communication function realizes “remote adjustment, telemetry, remote control, and remote communication.”
4.10 According to the requirements of 6.13 of GB13955 standard, after the installation is completed, the following inspection items must be available: press the “self-test” test button of the electrical fire monitoring detector to test whether the tripping action is performed. This test should be carried out one by one, with the test button continuously tested 3 times, should be correctly operated, the fire center alarm system should display the current status, address and automatically record; with rated load current 5 times, all reliable operation, should not There is a false alarm phenomenon; manual remote power-off test of each distribution box should be correct.
4.11 In the fire control center, the main unit of the leakage alarm system should be able to control the operation of any fault monitoring point. When the “test” button is pressed, the terminal console (the main body of the leakage alarm system) should be able to automatically receive the displayed fault status. Address code, record the current status and query.
4.12 Management system used by electrical fire alarm system: Under the condition of power-on state, you can temporarily allow power failure, press the test button to check whether the electrical fire monitoring detector is reliable. After the lightning fire or fire-fighting linkage power failure causes the electrical fire monitoring detector to operate, it should be checked. After the operation of the electrical fire monitoring detector, if the cause of the accident is not found after the inspection, the test is allowed to be sent once. If it is operated again, the cause should be found out and the fault should not be continuously transmitted. It is strictly forbidden to use electrical fire monitoring detectors after connecting and shorting the power-off device.
1. With the rapid development of electronic technology, remote control technology, bus technology, communication technology and other technologies, early detection and early warning of electrical fires will be realized, and fault information will be transmitted to the fire control center through the bus to display the fault address and fault information. Pre-alarms, troubleshooting by manual means, early detection and elimination of electrical faults.
2. With the wide application of electrical fire alarm system, the requirements of different project settings will be more and more detailed. For example, different places in the hospital must have different settings. The operating room and fire power supply should be set up with only alarms, and some hospitals are not. In important situations, both alarms and actions can be set.
3. The implementation of different projects is also different, and the new projects and renovation projects are different.
4. In short, the author calls on the relevant state departments to introduce relevant standards as soon as possible, so that the electrical fire alarm system can play its role and make due contributions to the protection of people's lives and property.