High-lift-off of rail displacement sensor using triangle spiral coil

Eddy-current rail displacement sensors are used for confirming rail displacement. However, collision with gravel and snow due to the short distance between rail head surface and sensor causes failures or malfunctions. Therefore, it is necessary to increase the distance from the rail head surface to the eddy-current rail displacement sensor. In this paper, the use of triangle spiral coils make rail displacement detection possible from the rail head surface, which is twice that of the conventional eddy-current rail displacement sensor up to a distance to the sensor.