Summary:Electrical faults are a significant cause of fires. Due to the fact that traditional fire alarms exist independently and lack networking and data synchronization, they may not respond promptly in the event of a fire. In order to achieve intelligent monitoring and management of fire incidents and fire-fighting facilities, IoT technology is applied to connect sensing devices, monitoring platforms, and monitoring systems together, enabling data sharing. By building an intelligent and secure fire-fighting system, rapid response and reduced customer fire losses can be achieved. The fire-fighting system data also provides data support for later maintenance.

keywordFire monitoring; Internet of Things; Smart Firefighting

0 Introduction

Shopping malls and residential areas with large populations are prone to fires, and the densely populated and complex environment makes them more prone to injury or death. According to data, there are two common ways of electrical fires: one is overheating type fire, where a certain part of the electrical equipment is overheated and not repaired in a timely manner, resulting in aging of the insulation layer of the circuit and even direct ignition of combustible materials. Possible overheating type fire situations may occur if the working voltage does not meet the rated voltage of the electrical appliance; Short circuit occurs in the wiring of electrical appliances; The conductor connection of the electrical appliance cannot be properly disconnected, resulting in an increase in the disconnection resistance; Frequent startup and shutdown of electrical appliances. Another type is discharge type fire, which may cause a short circuit, one-way short circuit, or open circuit in the wiring of useful electrical appliances due to the generation of sparks and arcs that ignite nearby objects; By using electrical appliances with excessive voltage, etc. In daily life, overheating electrical fires occur more frequently than discharge fires. In the face of this situation, China has installed fire detection and alarm systems in residential areas and large shopping malls. However, most fire alarms are used independently and the effect is not very ideal. This requires technological innovation, the addition of modern fire-fighting equipment, and networked management and monitoring systems.

Development analysis of domestic electrical fire monitoring system

The author believes that China's electrical fire monitoring system can be divided into three stages.

*The first stage is the multi wire system stage, during which electrical fire monitoring products can generally only be controlled using switch signals, and the signals of monitoring equipment and detectors are independent. The signal transmission between the two requires sensors to be completed, which requires more lines to connect. This not only increases costs, but also makes complex lines difficult for later maintenance. Early electrical fire monitoring systems in China mostly used this form called

*The second stage is a bus based stage, and with the advancement of communication technology, hardware costs are gradually decreasing. Bus technology is commonly used in monitoring equipment, including Controller Area Network (CAN) bus, dual bus, and RS-485 bus. Bus based electrical fire monitoring equipment utilizes digital signals rather than switch signals, which can reduce costs and more effectively and conveniently transmit detector data. Nowadays, the electrical fire monitoring equipment used in China is basically a bus based monitoring system. Although the scalability of this device is relatively poor, it has high stability.

*The three stages are the networking stage. With the maturity and application of 5G technology, more and more electrical fire monitoring equipment has entered the networking stage from the bus stage. In this stage, * the important thing is the Internet of Things technology. The Internet of Things is to connect various information sensors with Internet technology according to the specified protocol, which can carry out data transmission, information exchange and information processing. Through IoT technology, the wiring of electrical equipment can be remotely monitored by staff and directly linked to the alarm system of the fire department. Once an electrical fire alarm occurs, the fire department can be informed and arrive at the scene in a timely manner, effectively controlling the fire or minimizing damage. The fire alarm control system designed using IoT technology not only effectively solves the problem, but also effectively avoids electrical fires. Maintenance personnel can also accurately and quickly locate the fault location through networked electrical fire monitoring devices, thereby reducing the occurrence of electrical fires from the source.

As China's electrical fire monitoring equipment gradually moves from the bus based stage to the networked stage, many companies that produce electrical fire monitoring products not only combine the scientific and technological expertise of mature foreign products, but also customize them according to the characteristics of Chinese buildings, further promoting the rapid development of electrical fire monitoring equipment in China. Based on this, the author designed an electrical fire monitoring system based on Internet of Things technology.

Design of Electrical Fire Monitoring System Based on IoT Technology

2.1 Monitoring Structure Analysis

On the one hand, previous electrical fire monitoring equipment could only monitor individual buildings, so monitoring the entire shopping mall or residential area requires the installation of many monitoring devices. The more monitoring points there are, the more lines there are, and the more difficult it is to read data, which puts higher demands on the quality of the equipment. Especially in large buildings where pipelines and lines are densely packed, once a fire occurs, it will be difficult to control. Therefore, independent systems should be used to monitor different locations. Therefore, the author has designed electrical fire monitoring equipment for large shopping malls or residential areas with complex floor structures, aiming to achieve wider range control and more effective control. On the other hand, traditional fire monitoring equipment cannot effectively monitor large shopping malls and therefore cannot meet fire safety requirements; Maintenance is also relatively difficult, and once the line ages, it further increases the difficulty of updating and upgrading monitoring equipment. Based on the above analysis, it can be concluded that traditional monitoring equipment can only meet the needs of individual buildings. If it is to be applied to large buildings, an upper computer needs to be added to collect and summarize data from each building. This requires hardware improvement and updates, as well as reasonable modification and design of the upper computer to improve work efficiency and maximize data collection and summarization. Only by quickly identifying the problem can we effectively prevent fires. For large buildings such as shopping malls, 24-hour uninterrupted monitoring can be achieved through networked systems. This way, we can have a clearer understanding of the situation of electrical appliances and effectively prevent fires. The principle of the smart fire protection system based on IoT technology is shown in Figure 1.

By constructing the intelligent fire protection platform shown in Figure 1, not only can relevant information such as fire systems, fire equipment, fire facilities, and fire personnel be intelligently collected, but data analysis, processing, and intelligent decision-making can also be achieved. As an integrated service cloud platform, while providing 7 * 24-hour on duty services for homeowners, it can also monitor the operation of fire-fighting facilities in real time, provide customers with fire warnings and equipment failure prompts, and combine AI technology to achieve intelligent fire alarm analysis, so as to detect fire alarms and incidents in a timely manner. Through the 24/7 uninterrupted monitoring of the operation center management system, control over the progress and quality of management services is achieved; The visualization of fire risk elements, real-time warning, and intelligent safety management have been achieved through the use of fire butlers; Efficiently maintaining fire management through maintenance assistants has achieved multidimensional control.

2.2 Performance requirements for electrical fire monitoring and control system

Electrical fire monitoring equipment should meet the following requirements: when the equipment does not meet safety requirements, the system can conduct self inspection and check the monitoring points of the equipment at any time; When monitoring equipment detects abnormalities, it should promptly sound an alarm and provide accurate location and cause of the problem; When the changes in current and temperature at the monitoring point reach the warning values, promptly alert the host; Monitoring equipment should comply with relevant national regulations and cannot undergo significant modifications to the original equipment. The busbar in the circuit cannot be connected to the distribution box.

2.3 Design of Electrical Fire Monitoring System

The electrical fire monitoring system consists of two parts: the monitoring host and the detector. The monitoring host achieves 24-hour real-time monitoring. Once an alarm message occurs, relevant personnel should conduct timely inspection and handling, and notify maintenance personnel to arrive at the scene for fault detection and handling. The detector consists of three modules: electrical fire monitoring module, distribution line leakage monitoring, and temperature monitoring alarm module.

2.3.1 Design of Leakage Monitoring for Distribution Lines

Line leakage is a very serious problem, so it should be strictly monitored, especially paying attention to the following aspects: the alarm value of the monitoring system should be 80%~of the alarm system, and the alarm value range should be 20-10000mA; the uncertain warning range should be controlled within 3-4 times the power supply value, and should not exceed 100-300mA. For distribution lines, it should be set as secondary protection. **The level is generally the end of the line, and its function is to prevent the risk of electric shock. As an anti electric shock device, the end should choose an unsheathed RCD, and the head should choose an electromagnetic RCD. The current value should be less than 30mA. Since it works through fault current, it is independent of the voltage on the circuit, which can effectively improve accuracy. *The secondary protection mainly serves as a warning, and there will be a long delay from the occurrence of a fault to the occurrence of a fire, which can be effectively investigated using the secondary protection. When using, it should be ensured that the secondary protection is always in effect, as once the protection is tripped, it may cause unnecessary panic. The monitor includes two parts: the power circuit monitor and the lighting circuit monitor, which should be set to different thresholds and current alarm values. The current alarm value range of the power circuit monitor is usually 50-100mA, and the threshold range should be 200-300mA.

2.3.2 Requirements for Electrical Fire Monitoring Equipment

The power lines of electrical equipment are equipped with current sensors, current detectors, and distribution boxes. The current can be adjusted within the preset range. When it is necessary to set a leakage trip, a normal leakage trip circuit breaker can be used instead of a residual current circuit breaker; If leakage alarm is not required, an alarm type residual current detector can be used to reduce waste; Short circuit isolators can also be installed in the circuit to effectively prevent short circuits between the monitoring center and monitoring equipment.

Installation of Electrical Fire Monitoring System Based on IoT Technology

Normally, the detector and the detector will be installed together on the distribution door. As the detector needs to pass through the distribution circuit and be fixed in the frame, it is best to hand it over to the distribution cabinet manufacturer for installation to ensure correct installation. After finding the installation manufacturer, it is necessary to carefully review with the distribution cabinet manufacturer to ensure the correctness of the circuit connection by checking whether there are any problems with each circuit; Submit the appearance and equipment model of the detector and monitor again; Then proceed with on-site installation. Compared with other installations, the installation of electrical fire monitoring equipment is relatively simple due to the fewer number of wires in the circuit. However, attention should still be paid to the following aspects: when laying Category 5e unshielded twisted pair (UTP) cables, one should be reserved in the distribution box; After crimping the RJ45 crystal head, a line tester should be used to test the circuit and confirm that there are no issues before installation can proceed; The pipeline of the bus cannot be mixed with other strong or weak pipelines; It does not affect the components and circuits inside the distribution cabinet. The circuits inside the cabinet should be clear, tidy, and have a beautiful layout. After installation, the lines should be checked one by one to confirm that there are no problems before conducting a power on test on the fire detection equipment to ensure that the entire device is problem free.

4 Ankerui Electric Fire Monitoring System

4.1 Overview

Acre1-6000 Electrical Fire Monitoring System is a fully digital and independently operated system developed by Ankerui Electric Co., Ltd. in accordance with current national standards and regulations. It has passed the fire electronic product testing certification of the National Fire Electronic Product Quality Supervision and Inspection Center, and has undergone strict EMC electromagnetic compatibility testing to ensure the safe and normal operation of this series of products in low-voltage distribution systems. It has now been mass-produced and widely used throughout the country. The system achieves early prevention and alarm of electrical fires by collecting and monitoring signals such as residual current, overcurrent, overvoltage, temperature, and fault arcs. When necessary, it can also link and cut off distribution circuits that exceed the detected residual current, temperature, and fault arcs; And according to user needs, it can also meet the data exchange and sharing requirements with AcreIEMS enterprise microgrid management cloud platform or fire automatic alarm system.

4.2 Application scenarios

Suitable for intelligent buildings, high-rise apartments, hotels, restaurants, commercial buildings, industrial and mining enterprises, national fire protection units, as well as fields such as petrochemicals, education and health, finance, telecommunications, etc.

4.3 System Architecture

4.4 System Functions

1) The monitoring equipment can receive residual current and temperature information from multiple detectors, and emit sound and light alarm signals when an alarm is triggered. At the same time, the red "alarm" indicator light on the equipment is on, and the display screen indicates the alarm location and type. The alarm time is recorded, and the sound and light alarms are kept until the "reset" button on the equipment or touch screen is pressed to remotely reset the detector. The sound alarm signal can also be manually eliminated using the touch screen "mute" button.

2) When the monitored circuit alarms, the control output relay is closed to control the protected circuit or other equipment. After the alarm is eliminated, the control output relay is released.

3) Communication failure alarm: When there is a communication failure between the monitoring equipment and any connected detector or when the detector itself fails, the corresponding detector in the monitoring screen displays a fault prompt, and the yellow "fault" indicator light on the equipment lights up and emits a fault alarm sound. Power failure alarm: When the main or backup power supply fails, the monitoring equipment also emits sound and light alarm signals and displays fault information. You can enter the corresponding interface to view detailed information and cancel the alarm sound.

4) When residual current, over temperature alarm or communication/power failure occurs, the alarm location, fault information, alarm time and other information are stored in the database. When the alarm is cleared and the fault is eliminated, it is also recorded. Historical data provides multiple convenient and fast query methods.

5 Conclusion

With the rapid development of China's economy, the demand for electricity in large shopping malls, high-rise buildings, large-scale communities, and other urban landmarks is increasing. As electricity consumption increases, there are also more and more fires occurring. In order to avoid seriously affecting people's normal production and life, an electrical fire monitoring system is particularly necessary. Not only can it efficiently prevent electrical fires and reduce their occurrence from the source, but it is also of great significance for controlling electrical fires. The electrical fire monitoring system designed by the author not only has targeted functions, but also has strong real-time performance. As a system embedded in the distribution cabinet, it mainly monitors all line nodes in the covered areas in real time through relevant sensors and current detectors, which can meet the practical needs of applications.