Research of miniature magnetic coil sensor used for detecting power cables underground

Electromagnetic induction coils sensors can be used in the measurement of power cables underground and they provide the possibility of solving the problems of uncertainty of whether the power cables are destroyed and stop working. The induction coil sensor being investigated with its outer diameter and inner diameter are φ25 mm and φ12 mm respectively, and it was wound around a plastic skeleton of φ12 mm, the winding wire of the coil is enamelled wire with a diameter of 0.08 mm. The induced voltage from the coil sensor is pre-amplified through the audio frequency amplifier NE5532, with a second-order low pass filter to get rid of the high-frequency and other frequencies´ magnetic noise in the background. The measurement of the coil sensor is performed under the magnetic shielding room. We use the induction wire connected to the signal generator to simulate the power cables underground, and the frequency is set at 50 Hz. From the measurement results of the 50 Hz magnetic field generated form the simulated power cables; we get the sensitivity of the coil sensor 4.371 mV/nT. In this paper, we can conclude that the coil sensors can be used to detect the power cables underground.