| Recent years, with the development of power system infrastructure, the coverage of the transmission line is also rapidly expanded. Large-scale equipment like crane is commonly used in construction site. But workers cannot measure the distance between transmission line and equipment accurately. It would cause accident if the equipment breaks through safe area, maybe bring casualties.In this paper, we design an intelligent alarm device, which is installed on large-scale equipment like cranes. This kind of device is used to detect electric field intensity of transmission line and alarm intelligently when equipment breaks through safe area. This device would help workers to avoid accidents case by crane touch transmission line.The design of intelligent alarm device is mainly divides into two parts: electric field intensity detection and transmission unit, and electric field intensity reception and alarm unit. The electric field intensity detection and transmission unit is installed on the carne. While the other unit is installed in hand-held terminal, in charge of judge the distance and audible and visual alarm.The procedure of signal processing is: the collected signal would processed by filters firstly, then the signal enters the amplifier circuit, the next step is analog-digital converting, The main chip MSP430F5324 would process data of the signal, and then the radio frequency chip CC1101 is used to transmit wireless signal to the hand-held terminal device. The main chip would do data processing to judge if it need to sound and light alarm.In this paper, a method for collecting of power frequency electromagnetic signal of the high voltage transmission line is proposed: multi electrode electromagnetic grades detection. Because the electromagnetic environment of high voltage construction site is very complex, the single point electrode detection method can greatly reduce the accuracy of the collected signal. The multi electrode electromagnetic grades detection is based on the principle of the metal induced charge in the electric field, using eight pieces of strip electrode, and the electric field data are collected in each direction of the electric field environment.In this paper, we analyze the collected electric field data by the model of the power frequency electric field intensity and the safe distance of the high voltage transmission line. We build the electric field calculation model of the high voltage transmission line by the charge simulation method, and do experimental verification in the end. By using the device designed in the paper, the electric field signal data of different grades(220KV, 110 KV, 35KV) are collected at the scene of high voltage transmission line. The feasibility of the method of electric field intensity gradient detection and the electric field calculation model was verified.Through the experimental verification, the design of the sensor, multi electrode electromagnetic grades detection method and the establishment of electric field calculation model of high voltage transmission line, all greatly improve the accuracy of the crane alarm device. The device can prevent people and equipment from accident, and make sure electrical production in the construction site. |
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