Sensor and method for measuring the surface level of a liquid phase metal

A method for measuring a level in a continuous casting plant comprising an ingot mold having an upper face into which an opening, into which a liquid metal is fed, leads, wherein the method comprises:

• applying a voltage to an air excitation coil perpendicular to the upper face of the ingot mold and positioned in proximity to the opening, to create a magnetic field whose field lines are propagated along upper field lines which move away from the ingot mold and along lower field lines which cover the upper face of the ingot mold and the molten metal surface;
• measuring an induced voltage generated by the action of the lower field lines, the latter being likely to be modified by a variation of the level of the molten metal surface, in a lower air reception coil parallel to the excitation coil;
• measuring an induced voltage generated by action of the upper field lines, the latter being substantially free of disturbances generated by the molten metal surface, in an upper air reception coil parallel to the excitation coil, and superposed on the lower reception coil and with a geometry and characteristics identical thereto;
• comparing and digitally processing induced voltages measured in the lower and upper reception coils to obtain a value of the molten metal level in the ingot mold;
• measuring temperature of the ingot mold;
• correcting, by digital processing, a value of the molten metal level according to the temperature of the ingot mold.