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Shanghai Renwei Electronic Technology Co., Ltd. is an Internet of Things technology research and development and service company based on technology.In response to the business needs of large industrial enterprises,Internet of ThingsOver the years of accumulation in the application field, relying on strong R&D strength, based on Internet of Things technology (radio frequency RFID technology, video digital analysis technology, multi-function sensor technology, infrared and laser technology, etc.), combined with large industrial enterprises (electric power, The practical application of petrochemical, steel, metallurgy, etc.) provides enterprises with a variety of intelligent monitoring and management solutions. The main solutions are as follows:
• Wireless digital equipment inspection solution
Meet the needs of the actual inspection business process of industrial enterprises
Combine operation data collection with inspection work assessment
With the third-generation inspection technology as the supporting platform
On-site installation is simple and convenient, without wiring
• Wireless temperature monitoring solution
Effective combination of temperature sensing technology and wireless transmission technology
It is suitable for monitoring different applications such as switch cabinets, motor contacts and the surface of heat-prone objects
Just stick and use, no wiring, easy to expand the temperature measurement point
• Solution for wireless personnel safety monitoring in the factory
Effectively monitor personnel’s running track and working time in the factory
Effectively avoid safety accidents caused by personnel entering dangerous areas
Real-time location management and after-the-fact tracking analysis can be carried out for the personnel in the factory
1. The status quo of temperature monitoring of switch cabinets and transformer cabinets in industrial enterprises
1.1 Current status of switchgear temperature monitoring
At present, the temperature measurement of switchgear in industrial enterprises mainly includes optical fiber temperature measurement, infrared temperature measurement and video monitoring. For low-voltage cabinets, especially drawer switch cabinets, the method of patrol inspection infrared temperature measurement is generally adopted, but due to structural reasons, there is no effective real-time temperature monitoring method for the inside of the drawer cabinet. Moreover, because most of the low-voltage cabinets are domestically produced and the quality is relatively poor, in recent years, many industrial enterprises have frequent fire accidents with drawer switch cabinets. For medium and high voltage cabinets, although the cabinet body generally has its own optical fiber temperature measurement and the temperature can be displayed on the meter on the surface of the cabinet, it is impossible to transmit the temperature information back to the centralized control room for centralized monitoring in real time, and because the current in the medium and high voltage cabinets is relatively large Therefore, if the use time is longer (more than 5 years) or the screws of the interface are not tightened, it is easy to cause problems such as heat and damage to the busbar.
1.2 Limitations of other temperature measurement methods in switchgear temperature measurement
Optical fiber temperature measurement: The optical fiber temperature thermometer uses optical fiber to transmit signals. The temperature sensor is installed on the surface of a charged object, and the thermometer and the temperature sensor are connected by optical fiber. The optical fiber is easy to bend, break, and cannot withstand high temperature. After the accumulation of dust, the insulation will be reduced, and it is difficult to wire in the cabinet, and the cost is high; To measure internal equipment, you can only open the back door of the switch cabinet for measurement, which leads to poor measurement in many locations; Video monitoring and smoke detectors: When a fire occurs, usually, the fire risk starts from the inside of the switch cabinet, causing heat, burning, and radiation. Smoke, whether it is video monitoring or smoke detectors, when smoke is observed or detected, often a fire has occurred and losses have been caused.
2. Overview of the wireless temperature monitoring system
2.1 Features of RFID technology adopted by wireless temperature monitoring system
The wireless temperature monitoring system adopts the most advanced .18 chip long-distance RFID technology in the world. The characteristics are as follows: 1) RFID wireless network adopts 2.45GHz high-frequency signal transmission, which will not be affected by environmental factors such as temperature and humidity, and in industrial enterprises The electromagnetic waves and communication equipment do not interfere with each other, and accurate and clear information can be obtained; 2) RFID identification card has its uniqueness, and each card has a unique ID number, so that the temperature of the switch cabinet can be measured by the card to make the switch It is possible to distinguish between cabinets and between measuring points and measuring points in the same switch cabinet; 3) The dynamic conditions and real-time information of the temperature parameters in the switch cabinet can be reflected to the monitoring computer system in a timely and accurate manner, such as the temperature of the power cabinet When the value exceeds the normal value, the system will promptly alarm and notify the relevant personnel through sound, light and text messages to deal with it in time to avoid the occurrence of dangerous events; 4) The RFID signal is a digital signal, so it can be managed in many ways through software. For example, real-time temperature change curve, temperature history curve, switchgear temperature statistics table can be formed through RFID database. In addition to real-time monitoring of temperature parameters, it also allows managers to analyze temperature abnormalities in a certain period of time, thereby Identify problems and reduce safety hazards.
2.2 Network architecture of wireless temperature monitoring system
The wireless temperature monitoring system is mainly composed of two parts: the field and the control center.The site is remotely controlled by RFIDReader, It is composed of wireless temperature measurement card and wireless communication module, and the control center is composed of operator station and data server. The network composition of the wireless temperature monitoring system is shown in the figure below:
The main working principle: the on-site remote card reader wirelessly reads the device temperature information measured by the temperature measuring card, and transmits the information to the wireless communication module (production area) through the RS485 bus after preliminary processing, and then the wireless communication module in the production area transmits the data It is transmitted to the wireless communication module (office area) of the server in 2.45GHZ microwave mode. The wireless communication module of the server receives the data and then transmits it to the server. After the server obtains the data and processes it, it displays the relevant information on the monitoring screen in a graphical manner. And can analyze and alarm.
Every authorized user connected to the network can share information through the factory-level local area network, making management more convenient and faster. Then through the integrated short message sending device (SMS modem), when there is an emergency, the relevant information will be automatically sent to the manager’s mobile phone by means of short messages, so that the manager can respond as soon as possible.
2.3 Software function description of wireless temperature monitoring system
2.3.1 Real-time temperature monitoring
The screen displays the temperature of each switchgear measuring point in real time graphically, and provides alarm and alarm setting functions. The alarms are divided into over-temperature alarms and instantaneous temperature changes excessive alarms. The alarm temperature can be set according to user needs, and red means monitoring The arrived temperature has exceeded the set alarm temperature, double-click the temperature display in the screen, and the temperature alarm setting screen will pop up. Users can change the alarm limit according to their needs. When the measured temperature exceeds the alarm limit, an alarm will be displayed on the screen , To remind relevant personnel to pay attention and deal with it.
2.3.2 Temperature real-time/historical curve analysis
In the temperature data query and analysis function, real-time temperature curve query and temperature history curve query can be performed. In the temperature real-time curve chart, as time changes, the curve moves from right to left, forming a continuous curve. Users can intuitively see the law and trend of temperature changes with time. According to the curve, users can judge the switch cabinet temperature. Is it normal? In the historical graph, the user can conveniently query the temperature of the switch cabinet in the past period of time by setting the time interval, analyze the abnormal temperature, and deal with it in time, thereby reducing potential safety hazards. As shown below:
2.4 The hardware configuration and equipment parameters of the wireless temperature monitoring system
The hardware of the wireless temperature monitoring system includes data servers, wireless remote readers, wireless temperature measurement cards, wireless transmission modules, SMS modems and other equipment. The server serves as the software operating platform and data storage unit. Field devices send data to the server. The temperature monitoring management software reads the information in the database, and after processing, displays it to the equipment manager in intuitive forms such as screens or reports, so that the equipment temperature can be managed. More intuitive and convenient. Each temperature measuring card has its own unique ID and records the detailed information of the switch cabinet and measuring points. The administrator can clearly know the real-time temperature changes of each measuring point on the management side.
2.4.1 Introduction to equipment parameters
2.4.1.1 Wireless long-distance reader (NDS-70) Chinese name: directional long-distance reader;
Exterior:
2.4.1.2 Wireless temperature measurement card (card type RW-T500)
2.4.1.3 Wireless temperature measurement card (wire type RW-T600)
The temperature measurement module adopts PT100 thermocouple as the temperature measurement element. The size of the element is small, and the resistance value changes with the temperature change basically in a linear relationship. Within the temperature measurement range, the physical and chemical properties are stable, the long-term reproducibility is good, and the measurement accuracy is high. . If users have special needs, they can also specify the sensor by themselves.
2.4.2 System equipment characteristics
1. Ease of use of industrial control frequency bands
Due to the use of wireless transmission media, wireless sensor networks overcome many of the shortcomings of traditional wired networks to transmit information. Under some physical obstacles and special environments, wired networks are impossible to achieve; on the other hand, it is similar to traditional public network wireless communication. In contrast, 2.4GHZ industrial control frequency band wireless communication does not require the approval of the Radio Regulatory Commission, and does not need to pay spectrum occupation fees.
2. Low power consumption
The wireless sensor device used in the system adopts a reasonable sleep mode in technology, and has the characteristics of low power consumption for sending and receiving information. At the same time, the low-power design of the overall structure not only ensures the effective operation of the equipment, but also reduces the complexity and cost of application implementation.
3. The equipment is small in size
The basic unit of a wireless sensor network is a coin-sized intelligent computing sensor device. The integration and product quality of modern integrated circuit technology make the volume of wireless sensing devices continue to shrink, but the functions are becoming more and more powerful. The small size not only makes the application in special environments possible, but also greatly reduces the requirements and costs of installation and maintenance.
4. High capacity
The safety monitoring system of industrial enterprises can accommodate 640 long-distance card readers, and each long-distance card reader can collect more than 200 wireless temperature measurement card information at the same time. The entire system can accommodate hundreds of millions of identification cards, which is enough to meet the needs of existing large-scale industries. The needs of the business.
5. Precise and reliable
The accuracy, reliability, and stability of wireless sensor networks are more than a hundred times that of traditional methods.The core technology of the wireless sensor system currently uses the unique U-CORT algorithm, combined with distributed computing technology, neural network technology, and network information fusion technology to realize network self-recall
Wake up, self-tolerant, self-heal.
6. Low cost of operation and maintenance
When the system is expanded, any temperature measurement module set in the background can be automatically added to the network as long as it is placed within the coverage of the antenna signal. The high degree of intelligence minimizes the manpower and time required for network maintenance, plus network nodes Its low price makes the maintenance cost of wireless sensor network extremely low.
3. Temperature monitoring solution for XXX Power Generation Co., Ltd.
The first phase of XXX Power Generation Co., Ltd. consists of two 330MW circulating fluidized bed units, which were officially put into operation in February 2010 for power generation.
There are 35KV, 10KV, 6KV, 400V, 380V, 220V, etc. switch cabinets in the factory. The high-voltage switch cabinets are equipped with temperature monitoring devices when they leave the factory. 380V, 220V and other low-voltage switch cabinets are not equipped with temperature monitoring systems. At present, regular inspections are mainly used to monitor the temperature of the contacts through infrared temperature measuring devices. For the inside of the drawer, real-time and effective measurement cannot be carried out. Now the internal temperature of the existing drawer cabinet can be accurately monitored through the wireless temperature monitoring system, so as to achieve real-time control, find abnormalities and deal with them in time, and improve the safety factor of the switch cabinet;
Transformer cabinets are equipped with temperature measurement and display devices. However, considering the failure rate of the self-contained temperature measurement devices and the problem that the data cannot be monitored in real time in remote locations, the transformer cabinet is now installed with wireless temperature measurement devices to monitor important measurement points in real time. temperature change.
3.1 Arrangement of remote card reader and wireless communication module
The power distribution room is shown in the figure below.
The long-distance card reader can be installed in the center of the ceiling of the control room and connected to the 220V power supply; the wireless communication module is installed near the window and connected to the 220V power supply. Each control room is equipped with 2 wireless long-distance readers (which can monitor 300 temperature measurement points at the same time) and 1 wireless communication module.
3.2 Arrangement of wireless temperature measurement card in switch cabinet
Each drawer of the low-voltage switch cabinet is equipped with a wireless temperature measurement card. According to the structure and heating position inside the drawer, the temperature monitoring card should be arranged near the heating source; each cabinet in the 6KV switch cabinet is ABC three-phase Arrange 3 wireless temperature measurement cards. As shown below:
In order to ensure the accuracy and effectiveness of the measured temperature, the wireless temperature measuring card is glued to the side of the switch plastic shell close to the contact of the incoming and outgoing wires.
The wireless transmission distance of the wireless temperature measurement card signal after the cabinet door is closed is about 20-50 meters, and the transmission frequency is 3-5 seconds.
3.3 Arrangement of wireless temperature measurement card in transformer cabinet
Each transformer cabinet is divided into three phases, A, B, and C, and one wireless temperature measurement card is installed for each phase, as shown in the following figure:
The wireless transmission distance of the wireless temperature measurement card signal after the cabinet door is closed is about 20-50 meters, and the transmission frequency is 3-5 seconds.
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