| 摘要 |
<p>PURPOSE:To make the detection of an electrical insulating spot possible by providing a pair of transmitting coils longitudinally in parallel with a space taken so that the direction of a magnetic pole may be a negative phase, and executing detection at a position where a receiving coil approachs the transmitting coil. CONSTITUTION:A pair of transmitting coils 2, 2 connected in series is longitudinally provided at an interval taken so that the direction of a magnetic pole may be a negative phase, and a receiving coil 3 is provided in a lateral direction crossing the arranging direction of the transmitting coils 2, 2 at right angles and moreover longitudinally in parallel. In the case where the electrical insulating spot of the insulating coupling of a buried pipe 11 is detected by a detector 10, measuring lines rectangular to an axial direction are set up at plural positions along the assumed axial direction of the pipe 11. The device 10 is moved in a state where in each measuring line, each arranging direction of the transmitting coils 2, 2 crosses the assumed axial direction at a right angle for measuring. The strength of a detected magnetic field is maximum when the pipe 11 takes a position just above the pipe 11. In addition, when the peak value of the strength of the detected magnetic field is displayed to the axial direction of the pipe 11, it becomes minimum at the spot of the insulating coupling, and the position of the insulating coupling can thereby be detected.</p> |
