Electromagnetic method and system using voltage induced by a decaying magnetic field to determine characteristics, including distance, dimensions, conductivity and temperature, of an electrically conductive material

A measuring system for the contactless measuring of absolute parameter magnitudes of or related to an electrically conductive material in a solid or liquid form, such parameters comprising at least one of the distance of the material from a given point, linear dimensions of a body that contains such material, the electrical conductivity of said material or its temperature, with the aid of means which cause an electromagnetic field to penetrate the material at least partially, the system comprising:

• at least one magnetic field generating coil,
• at least one sensing coil dispensed at said given point,
• first means connected for supplying a constant current to said at least one magnetic field generating coil,
• second means for interrupting the current supplied by said first means to said at least one coil subsequent to said field having penetrated the material to an extent sufficient to measure the value of the intended parameter, and
• third means for subsequently sensing the voltage which is induced in at least one sensing coil located at said given point in said magnetic field as a result of the decaying magnetic field subsequent to interruption of the supply current, said sensed voltage comprising an initial portion corresponding to the decay of the magnetic field across said distance parameter during an initial, very short time period on the order of microseconds beginning with the discontinuous of the current supply and said initial portion of said sensed voltage being used as a basis for determining the absolute value of said distance parameter.

A method for the contactless measuring of absolute parameter magnitudes of or relating to an electrically conductive material in solid or liquid form, such parameters comprising at least one of the distance of the conductive material from a given point, linear dimensions of a body that incorporates said material, the electrical conductivity of the material, and the temperature of said material, in which method an electromagnetic field is caused to penetrate the material at least partially, comprising:

• generating the electromagnetic field during at least a first period with the aid of a constant current which flows through at least one field generating coil;
• discontinuing the supply of current to said at least one coil at the end of said first period, subsequent to the magnetic field having penetrated the electrically conductive material to an extent sufficient for the intended parameter to be measured,
• sensing the voltage which is induced in at least one sensing coil located in the magnetic field at said given point as a result of the decaying magnetic field, following said first period and during a second period, said sensed voltage comprising an initial portion corresponding to the decay of the magnetic field across said distance parameter during an initial, very short time period on the order of microseconds beginning with the discontinuance of the current supply;
• and
• utilizing said initial portion of the sensed voltage to determine the absolute value of said distance parameter.