MEASUREMENT OF TRANSFORMATION AMOUNT RATIO BY AC CURRENT

摘要

PURPOSE:To make it possible to almost disregard the influence of the interval between an object to be measured and a sensor, by positioning a transmission coil and receiving coil in opposed relationship so as to interpose a plate shaped object to be inspected therebetween. CONSTITUTION:When a sine wave shaped continuous current is flowed to a transmission coil 21, an eddy current is generated to the surface of a plate shaped object 23 to be inspected and the voltage induced at both terminals of a receiving coil 22 by the change of a magnetic field is shown by formula and a transformation amount ratio K can be calculated. There is no term showing the interval between a sensor and the object to be inspected in the formula and the transformation amount ratio drawn out from induced voltage receives no influence of the interval between the sensor and the object to be inspected.