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Description
In the project construction and daily maintenance of overhead power distribution lines, it is necessary to know the actual situation of the auxiliary parts for power polses, such as chassis, chuck and puller, to prevent the poles from pulling up, sinking and lodging. But due to the inconvenient excavation of power poles or the large amount of excavation work, trenchless detection technology is put forward to detect the status of chassis, chuck and puller underground, and provides a research opportunity for electromagnetic detection methods. This paper proposes a trenchless detection method based on transient electromagnetic method, which realizes underground detection by transmitting, receiving and processing electromagnetic signals generated by underground conductors. In this paper, a prototype of transient electromagnetic detector is designed on the base of theoretical analysis and mathematical modeling for the chassis, chuck and puller underground. The prototype consists of a transmitting power supply, a transmitting coil, a receiving coil and a signal processor.The transmitting power supply generates a flat-top pulsed current with a high change rate of 20 A/us, thus enhancing the magnetic field signal returned from the measured object.The transmitting coil and receiving coil are the same solenoid structure with parameters of 40 turns and 300mm diameter. In order to reduce the influence of mutual inductance between transmitting coil and receiving coil, two coil are placed side by side. The prototype is tested with the chuck 1.5 meters deep, chassis 3 meters deep and puller respectively in the field of practical application. Through the analysis of the experimental results of multiple test objects, the transient electromagnetic detector can realize the detection as designed, and the precision of measurement reaches 90%.
