Study on High Lift-Off of Eddy Current Type Rail Displacement Sensor by High Quality Factor

Abstract

　As the conventional eddy current type rail displacement sensor has a small distance (liftoff) from the railhead top surface to a sensor, there is the possibility that a sensor wakes up trouble and malfunction for a collision with the snow and the gravel. As the conventional triangle coil has low Q level, a change of the impedance to depend on rail displacement for when I raise a liftoff is not provided enough. Therefore, the problem that the detection precision of the rail displacement falls to occurs. In this article, I improved a Q level by becoming examination, the high frequency of the drive circuit of the coil structure and enabled measuring it at 50mm that was conventional double size by a liftoff.