An Kerui Shi Qingqing Jiangsu Ankerui Electric Appliance Manufacturing Co., Ltd. Jiangyin, Jiangsu 214405
Abstract: School-type public cultural institutions have the characteristics of dense population, strong social influence, and high social attention. Their electrical fire safety is very important. In view of the characteristics of high concentration of personnel in school class venues and high safety requirements for personnel, the country and regions have established relevant electrical fire prevention and some mandatory regulations. The installation of electrical fire monitoring systems in the above-mentioned various personnel-intensive locations can effectively prevent the occurrence of electrical fires. This article describes the application of the Acrel-6000/B electrical fire monitoring system in the Shanghai Fudan Higher Art Training Base Project, briefly analyzes relevant national standards and design specifications, and outlines the specific structure of the electrical fire monitoring system in electrical fire prevention. And its superiority.
Keywords: Public buildings; Electrical fires; Shanghai Fudan Higher Art Training Base; Ankerui; School;
0 Foreword
In the recent ten years of fire accidents, electrical fires took the lead, and the average annual number of fires accounted for 27% of the total number of fires per year, accounting for 80% of the total number of major fires, and the loss accounted for 53% of the total fire losses. The number of electrical fires in developed countries accounts for 8% to 13% of the total number of fires each year. In fact, electrical fires have become the main disaster-causing factors for fire safety. Not only are they more frequent and more costly, they have also been high for many years. Public welfare public buildings have the characteristics of dense personnel, frequent contacts, and high degree of public concern, making the prevention of electrical fires in distribution systems more important.
There are two main aspects of electrical fire prevention in public buildings:
(1) Electrical fires usually start inside electrical cabinets, cable trays, etc. When the fire spreads to the surface of equipment and cables, a large fire has already formed. At this time, the fire is often not easily controlled, so prevention is very important.
(2) There is a high degree of social concern in school-type public places. If a fire occurs, it will affect the progress of related social activities and may cause loss of people's lives and property.
For the above two aspects, Ankerui Electric Co., Ltd., based on its own ARCM series of electrical fire monitoring detectors, developed the Acrel-6000 by integrating RS485 bus technology and terminal computer software display technology. / B Electrical fire monitoring system. The background of the system displays the data of each detection point, and it also provides functions such as over-limit sound and light alarm and user-friendly interface. The system realizes 24-hour unmanned real-time monitoring of the power distribution system, reduces labor costs, and improves the elimination efficiency of electrical fire hazards.
This article briefly introduces the practical application and its practical significance of Acrel-6000/B electrical fire system in the application of electrical fire system in Shanghai Fudan Higher Art Training Base Project.
1 Project Overview
Shanghai Fudan Higher Art Training Base is a teaching base established by the Shanghai Visual Arts Institute in Songjiang. Shanghai Institute of Visual Art (abbreviated as Shangshi), formerly Shanghai Institute of Visual Arts, Fudan University, is an advanced art college specializing in communication research and design research. It was established in 2001 and officially established in 2005. Start school. In April 2013, with the approval of the Ministry of Education, it was detached from the subordinate department Fudan University, changed from an ordinary college independent college to an ordinary private college, and changed its name to Shanghai Visual Arts Institute. The school is located in the Songjiang University campus and covers an area of ​​nearly 1,000 acres. The construction of the campus and the investment in fixed assets exceeded RMB 600 million. The total construction area of ​​the school building was over 120,000 square meters, and the student apartment area was 41,840 square meters. It is now a key private arts undergraduate college of the Shanghai Municipal Education Commission.
This project is mainly designed for the design of electrical fire monitoring systems in two teaching buildings in the Fudan Advanced Art Training Base in Shanghai.
According to the characteristics of this project, ARCM series residual current electrical fire monitoring detectors developed by Ankerui are installed in the important circuits of the power distribution cabinets on some floors. The electrical fire monitoring system must monitor the residual current value of the important circuit and the real-time temperature of the cabinet circuit in real time. The monitored data is transmitted to the back-end host in real time. When the remaining current value is exceeded and the temperature exceeds the limit, an audible and visual alarm can be performed in the background. The background can be linked with the fire fire alarm system to achieve fire protection linkage.
2 Reference standards
In view of the fire in public buildings, it is easy to cause loss of life and property. In order to increase the intensity of the prevention of electrical fire monitoring, in recent years, the state has successively formulated or revised a number of relevant standards and specifications. The relevant standards and specifications have put forward specific requirements for the electrical fire monitoring system. The design standards of the Acrel-6000/B electrical fire system chosen for this project are:
(1) GB50045-95 (2005 edition) "Design Code for Fire Protection of High-rise Civil Buildings", which states in Article 9.5.1 that a fire-fighting fire alarm system should be set up in high-rise buildings with high fire risk and dense personnel.
(2) The relevant provisions of the national standard “Building electrical fire prevention requirements and detection methods†also clearly require that “the residual current operation protector that automatically cuts off the power supply or alarm should be installed at the power input end.
(3) Products of electrical fire monitoring system shall meet: GB14287.1-2005 "Electrical fire monitoring equipment", GB14287.2-2005 "residual current electrical fire monitoring detector", GB14287.3-2005 "temperature measurement type electrical Fire Monitoring Detector"
(4) The installation and operation of the electrical fire monitoring system shall meet GB13955-2005 "Installation and operation of residual current protection devices"
(5) The power supply for the electrical fire monitoring system shall meet the requirements of GB50052 "Design Specification for Power Supply and Distribution System".
(6) The design of electrical fire monitoring systems should meet the requirements of the "Design Method for Electrical Fire Monitoring Systems" (Interim Provisions)
3. System Architecture and Design
Electrical fire monitoring system topology
1) Station control management
Station management The management personnel of the electrical fire monitoring system are the direct windows of human-computer interaction and the top part of the system. The host of the Ancorui electrical fire monitoring system fully takes into account the user's operating habits, and continuous and stable operation, with reference to the corresponding national standards and specifications. The host is mainly composed of monitoring software, touch screen, UPS power supply, printers and other equipment. The site's various types of data information are calculated, analyzed, and processed, and graphically, digitally displayed, voiced, and indicator lights reacted to terminal managers. Enables managers to grasp system dynamics in real time, and implement fault information that can be followed, and information can be exported.
In view of the scale of the instrument point and the amount of data in this project, the Acrel-6000/B host is currently configured for the project. The specific parameters of this host are described below.
2) Network communication layer
All instruments in this project must be connected in a strictly hand-in-hand manner, and all communication buses must be laid along weak bridges. The instrument of this project is distributed in the electric fire monitoring and detection between the floors of strong electricity.
The data bus of this project is designed as two buses. The independent bus facilitates the maintenance of the system in the later period. When a leakage current alarm occurs, the fault circuit can be quickly located according to the check table provided by us in the later period to quickly eliminate the fault.
The on-site electrical fire detectors use a twisted-pair cable (ZR-RVSP2*1.0) to communicate with each other in a hand-in-hand manner. The number of meters per bus is about 20 units.
3) Field device layer
In this project, ARKRAY embedded electrical fire detectors are installed for the incoming circuit of the floor distribution box. The embedded electrical fire detectors are used to monitor the leakage current of the distribution circuit in real time to display the working status of the entire distribution system. .
The ARCM series residual current electrical fire monitoring detectors are designed for TT and TN systems up to 0.4kV, and monitor and manage the fire hazard parameters such as residual current, wire temperature, overcurrent and overvoltage in the distribution circuit. This prevents the occurrence of electrical fires and enables real-time monitoring of multiple power parameters to provide accurate data for energy management. Products using advanced microcontroller technology, high integration, compact size, easy installation, set intelligent, digital, network in one, is the building electrical fire prevention and control, system insulation, such as the estimated aging of the ideal choice. The product complies with the standard requirements of GB14287.2-2005 "Electrical fire monitoring system Part 2: Residual current electrical fire monitoring detector".
4 system features and working principle
In view of the scale of this project, the actual situation of the project's electrical fire detection point. Both the terminal residual current detector and the background host are designed according to the actual situation of the project.
4.1 The system characteristics of this project can be summarized as follows:
(1) The terminal detector uses an embedded electrical fire detector to facilitate installation, save costs, and facilitate post-maintenance.
(2) RS485 bus connection is convenient and operability is strong. When the bus is routed, it is a weak bridge and will not be affected by strong electricity, ensuring the stable communication of the entire system.
(3) Taking into account the data volume of the instrument in this project, customer requirements. The host of this project is wall-mounted. The wall-mounted host interface is concise and the system is easy to operate. It is suitable for the power distribution room environment and customer's related operation requirements in this project.
4.2 Working Principle of Electrical Fire System
(1) Residual current measurement is based on Kirchhoff's current law: At the same time, the vector of the current flowing into and out of a node in the circuit is zero. Taking the TN-S system as an example, the A/B/C/N is passed through the residual current transformer at the same time. When the system is not leaking, the current vector flowing into and out of the residual current transformer is zero, and at this time, the residual current The secondary current induced by the transformer is also zero; when a leakage occurs on a relatively large ground, the current vector at the time of flowing into and out of the residual current transformer is no longer zero, and its magnitude is equal to the current flowing from the ground, ie, the leakage current. The leakage signal is transmitted to the electrical fire detector through the secondary wiring of the residual current transformer, and is subjected to operation amplification, A/D conversion and sent to the CPU. After a series of algorithms, the amplitude of the change is analyzed, judged, and The alarm set value is compared. If the value exceeds the set value, an audible and visual alarm signal is sent and sent to the back-end electrical fire monitoring equipment.
(2) The terminal detector is responsible for monitoring the residual current of each loop and transmitting the residual current data to the system host. The terminal detector is also responsible for the real-time display of the residual current value of its monitoring circuit. At the same time, it can set the limit value. When the residual current value exceeds the limit, an audible and visual alarm can be issued to remind the management personnel to maintain and rectify in time.
(3) The instrument transmits the data to the system host through the RS485 bus. The system host will upload the data to reflect the running status of the entire system through the form of graphs, reports, and event records.
5 System Design Considerations and Methods
5.1 The electrical fire monitoring system mainly monitors the following two types of objects: residual current and temperature.
(1) Residual current
Since the principle of residual current monitoring adopts Kirchhoff's current law, there is a certain requirement for the form of the applied low-voltage power distribution system. At present, low-voltage power distribution systems that can use residual current transformers are: TT systems, IT systems, TN-S systems, and cannot be used in TN-C systems. For users who will design and install an electrical fire monitoring system, whether it is a new project or an old one, it is necessary to first investigate and verify what the system grounding form of the user's low-voltage power distribution system is. Otherwise, design and install the point of the residual current transformer. Testing is simply not possible.
With regard to the AC220V single-phase power supply system, the residual current transformer may only cover two L/N power lines, but it is required that the neutral line N is not allowed to be grounded thereafter. For the AC380V three-phase power supply system, due to the use of three-phase three-wire system, three-phase four-wire system, three-phase five-wire system, etc., according to the specific circumstances of the residual current transformer will be at the same time jacketed A / B / C three-phase power line, Or cover the A/B/C/N line at the same time. Similarly, it is required that the neutral line N is not allowed to be grounded after that and the protection line PE must not pass through the transformer.
When the system is grounded in the form of a TN-C type industrial automation network, it must be converted to a TN-S type, TN-CS type, or a local TT type system before the residual current detection device can be installed.
(2) About temperature
The temperature measurement has nothing to do with the form of system grounding. It mainly considers the temperature of key parts in low-voltage power distribution equipment, including cables, and is generally applied in the secondary protection circuit. The temperature probe Pt100 can adopt the contact arrangement method. When the detected object is an insulator, the temperature sensor of the detector should be set directly on the surface of the object to be detected. When the detected object is a change in the internal temperature of the distribution cabinet, a non-contact arrangement can be used, close to the heat-generating components.
5.2 Point allocation in system design
According to the provisions of the national standard GB13955-2005 “Installation and Operation of Residual Current Operation Protection Device†4.4, concerning graded protection, when installing the residual current fire monitoring device, the steps of point allocation principle are:
(1) Study and analyze the relevant drawings of the controlled low-voltage AC380V/220V distribution line, investigate and verify the distribution of the building electrical, and determine the location of the distribution equipment (such as distribution cabinets, boxes, trays, cables and other important equipment). Each monitoring detector is assigned to the corresponding distribution equipment to determine the number of detectors and avoid resetting waste.
(2) Determine graded protection. In order to reduce the scope of power outage caused by personal accidents and ground faults when the power is cut off, three-level (or two-level) residual current protection devices of different capacities are usually installed at different locations of the power supply line to form a hierarchical protection. According to the power load and the line conditions, it is generally divided into two or three levels of protection, which is suitable for the protection of the first and second levels in urban and rural areas.
Among them, the important lines should include security, fire protection, emergency power supply, channel lighting lines and important places that do not allow blackouts.
(3) In the secondary protection, all switches must be installed with a residual current fire monitoring detector, that is, both at the power end of the line (first stage protection) and at the beginning of the branch (second stage also called end protection). Install residual current detectors and access electrical fire monitoring systems for fire monitoring alarms only.
(4) Temperature detection is based on the basic principle of heat generation in abnormal distribution equipment.
1) transformer low voltage side outlet terminal, transformer body temperature (wind temperature, oil temperature, water temperature) test point, load switch contacts.
2) Access points of the power distribution cabinets (boxes), contact points of automatic switches (circuit breakers, knife switches), concentrated current conductors, and cable connection points.
3) Master contact, knife switch contacts.
4) Compensation capacitor terminals and transfer switch contacts.
5) According to the total number of points installed, then select the appropriate wall, vertical or Qintai.
6 System Parameter Configuration
6.1 Setting range of alarm value
The residual current alarm value of the on-site instrument in this project is set at 300mA. The setting of the residual current value has detailed provisions in the relevant national standards.
According to the provisions of the national standard GB14287.2-2005, the alarm value of the residual current type electric fire monitoring detector is set in the range of 20~1000mA. According to this requirement, the residual current operating value at the total power supply line is generally set to 400~800mA, and the residual current operating value on the power branch line is set to 100~400mA. Generally, in the actual site, the residual current type electric fire monitoring and detection is set. The alarm value of the device shall not be less than 2 times the maximum value of the leakage current during normal operation of the protected electrical circuit and equipment, and shall not be greater than 1000 mA. Electrical fire detectors' alarm settings should take into account the normal leakage currents of the distribution system and electrical equipment.
6.2 About the cable temperature rise alarm setting reference, according to "power cable design specifications" on the cable temperature requirements
(1) High temperatures above 60°C should be selected according to the high temperature, duration, and type of insulation. Heat resistant PVC, XLPE, or EP rubber insulation, etc. should be selected. High temperature above 100°C. Insulated cable. High-temperature places should not use ordinary PVC insulated cables.
(2) The ambient temperature of the cable that allows constant current carrying capacity shall be determined according to the multi-year average of the meteorological temperature in the area of ​​use and shall comply with the regulations. When laying the cable trench in the house, the ambient temperature is the average of the highest daily temperature in the hottest month of the site plus 5°C.
(3) The temperature rise of the cable is related to laying and heat dissipation conditions.
7 major equipment parameters
The electric fire monitoring system of Shanghai Fudan Higher Art Training Base Project consists of an electrical fire monitoring device Acrel-6000/B, a leakage fire detector ARCM200L-J1, and a leakage current transformer AKH-0.66L. With regard to instrumentation and instrument transformers, we will not introduce them here. . Cn query.
7.1 Main Technical Parameters
power supply:
1 rated working voltage AC220V (-15% ~ +10%)
2 Standby power supply: When the main power supply is under voltage or power failure, maintain the monitoring equipment working time ≥ 4 hours
Work system:
24-hour work
communication method:
RS485 bus communication, Modbus-RTU communication protocol, transmission distance 1.2km, can extend communication transmission distance through repeater
Monitoring capacity:
1 monitoring equipment can monitor up to 1024 (to be customized) monitoring unit (detector)
2 can be connected with ARCM series monitoring detector
Monitoring alarm items:
1 Residual current fault (leakage): Fault cell attributes (part, type)
2 Temperature alarm (over temperature): Fault cell attributes (part, type)
3 Current fault (overcurrent): Fault cell attributes (part, type)
Monitoring alarm response time: ≤30s
Monitoring alarm sound pressure level (A weighting): ≥70dB/1m
Monitoring alarm light display: red LED indicator, red light alarm signal should be maintained until manual reset
Monitoring alarm sound signal: Can be eliminated manually, when it is alarm signal input again, it can start again
Fault alarm item:
1 An open circuit or short circuit occurred in the communication cable between the monitoring equipment and the detector
2 Monitoring equipment main power supply undervoltage or power failure
3 An open circuit or short circuit occurred in the connection between the battery charger and the battery
Fault alarm response time: ≤100s
Monitoring alarm sound pressure level (A weighting): ≥70dB/1m
Monitoring alarm light display: yellow LED indicator, yellow light alarm signal should be maintained until troubleshooting
Fault alarm sound signal: Can be eliminated manually, when it is alarm signal input again, it can start again
During faults, normal operation of non-failed circuits is not affected
Control output:
Alarm control output: 1 set of normally open passive contacts, capacity: AC250V 3A or DC30V 3A
Self-inspection project:
1 Indicator Check: Alarm, Fault, Operation, Main Power, Standby Power Indicator
2 display check
3 audio device inspection
Self-check time ≤60s
record:
1 Record content: record type, occurrence time, detector number, area, fault description, no less than 20,000 records can be stored
2 record query: according to the record of the date, type and other conditions
Operation rating:
1 daily shift: real-time status monitoring, event record query
2 monitoring operation level: real-time status monitoring, event record query, remote reset of the detector, device self-test
3 System management level: real-time status monitoring, event record query, remote reset of detector, device self-check, system parameter query of monitoring equipment, individual detection of each module of monitoring equipment, operator addition and deletion
Use environmental conditions:
1 Workplace: fire control room, manned power distribution (distribution room), on-call room walls
2 working environment temperature: 0 °C ~ 40 °C
3 working environment relative humidity: 5% to 95% RH
4 Altitude: ≤2500m
7.2 Basic functions
(1) Monitoring alarm function:
The monitoring equipment can receive the leakage and temperature information of multiple detectors. When the alarm sounds, an audible and visual alarm signal is emitted. At the same time, the red “alarm†indicator light on the equipment is on. The display indicates the alarm location and the type of alarm. The alarm time is recorded and the sound and light alarm is maintained. , until the display reset button remote reset the detector. The audible alarm signal can also be manually cancelled using the display “Mute†button. 
(2) Fault alarm function
Communication failure alarm: When a communication failure occurs between the monitoring device and any connected detector, the corresponding detector in the monitoring screen displays a fault prompt, and the yellow “fault†indicator on the device lights up, and a fault alarm sound is emitted. .
Power failure alarm: When the main power supply or backup power supply fails, the monitoring device also emits an audible and visual alarm signal and displays the fault information. You can enter the corresponding interface to view the detailed information and cancel the alarm sound.
(3) Self-test function
Check if all status indicators, display screens, and speakers in the device are normal.
(4) Alarm record storage inquiry function
When leakage, over temperature alarm, or communication or power failure occurs, the alarm location, fault information, alarm time, and other information are stored in the database. When the alarm is removed and the fault is eliminated, it is also recorded. Historical data provides a variety of convenient and fast methods for searching.
(5) Power Function
When the main power supply has a power failure or undervoltage, the monitoring device can automatically switch to the standby power supply. When the main power supply resumes normal power supply, it automatically switches back to the main power supply, ensuring continuous and smooth operation of the monitoring device during the switchover process.
(6) The detector control function
By monitoring the software operation, remote reset control can be performed on all detectors connected to the device.
(7) permission control function
In order to ensure the safe operation of the monitoring system, the monitoring device software operating authority is divided into three levels, and different levels of operators have different operating rights.
Project summary
During the implementation of this project, we assisted the construction company to guide the laying of communication cables and to eliminate the hidden dangers of the leakage current in some of the incoming circuits. The large leakage current is mainly due to the partial loop neutral connected to the ground.
The whole process of design, installation, commissioning and acceptance of the electrical fire system is not only a comprehensive inspection of electrical safety, but also a comprehensive training for the users of the electrical distribution system management personnel. Through the implementation of the project and the training of the system application, the project The power system administrators can understand the electrical fire hazard elimination methods of the project's distribution system in more detail and improve their electrical fire prevention awareness and efficiency.
After the project is running normally, we also provided the complete set of data for the electrical fire system of this project. The data includes the point table of the electrical fire detection point of this project, and the system operating instructions. As far as the point table is concerned, the specific name and position of each fire detector installation circuit in the project is marked on the above, and the real-time data after the normal operation of the system. The full set of data facilitates late management personnel to quickly grasp the system architecture, improve system maintenance efficiency and troubleshooting speed.
references
[1]. Ren Chengcheng, Zhou Zhong. Principles and Application Guide for Digital Meters for Electric Power Measurement [M]. Beijing. China Electric Power Press, 2007. 4
[2].Zhou Zhong. Application of Power Meters in Energy Metering of Large-scale Public Buildings [J]. Modern Building Electronics 2010. 6
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