Abstract: A method of taking a plurality of measurements of the magnetic field using the plurality of sensors; includes assessing the inductive magnetic excitation; and determining the likely distribution of magnetic sources on the surface of the hull by resolving a system of equations derived from modeling the physical phenomena at play, on the basis of the plurality of measurements taken and the assessed inductive magnetic excitation. The model describes the induced magnetic sources as a distribution of dipolar sources and the remanent magnetic sources as a distribution of monopolar sources. A device (6) for determining the magnetization of the hull of a ship for implementing the method is also described.

Abstract: A method and a system for controlling the switching time of a device that includes a magnetic circuit and a conductive winding. The method includes acquiring a measurement of the magnetic field generated by the residual flux, by a sensor placed near the magnetic circuit; processing the acquired measurements to infer the residual flux in the magnetic circuit; determining, on the basis of the residual flux, the optimal time for switching on the device. The method also includes switching on a three-phase transformer. The transformer includes a primary conductive winding and a secondary conductive winding surrounded by an enclosure. A magnetic field sensor is on the magnetic circuit and/or on one outer surface of the enclosure.

Abstract: In various embodiments, apparatus and methods of operating the apparatus are provided to determine existence and location of parasitic stress threes on a rod portion, the rod portion made of a magnetostrictive material and having a hollow tube. The apparatus may include a device comprising an envelope made of a non-magnetic material, a magnetic field source disposed inside the envelope, a motor to set the magnetic field source in rotational motion on the inside of the envelope, and a sensor to measure a value of the magnetic field and to deliver a signal representative of the value of the magnetic field. Operation of the apparatus may include penetration of the envelope into a portion of the hollow tube of the rod portion and translation of the envelope along the portion of the hollow tube. Additional apparatus, systems, and methods are disclosed.

Abstract: The invention relates to a method and a system for controlling the switching time of a device that includes a magnetic circuit and a conductive winding. Said method includes the steps of: acquiring a measurement of the magnetic field generated by the residual flux, by means of a sensor placed near the magnetic circuit; processing the acquired measurements so as to infer therefrom the residual flux in the magnetic circuit; determining, on the basis of the residual flux, the optimal time for switching on the device. All of said steps are carried out after the device has been switched off. The invention also relates to the use of said method to switch on a three-phase transformer. The invention relates to a transformer comprising a primary conductive winding and a secondary conductive winding surrounded by an enclosure and, on the magnetic circuit and/or on one outer surface of the enclosure, a magnetic field sensor belonging to said system.

Abstract: An apparatus comprising a probe having an elongated probe casing includes a magnetometer and a permanent magnet having a north-south magnetic axis disposed in an orientation relative to a longitudinal axis of a drill string or pipe casing when the probe is inserted into the drill string or the pipe casing. The permanent magnet is disposed in a non-vertical plane that does not contain the longitudinal axis to induce a magnetic field in the plane from the north of the magnetic axis to the south of the magnetic axis along a portion of a circumference of the drill string or the pipe casing. The magnetometer is to detect magnetization of the drill string or the pipe casing independently of movement of the permanent magnet. Additional apparatus and methods of analysis using the apparatus are disclosed.

Abstract: A method of taking a plurality of measurements of the magnetic field using the plurality of sensors; includes assessing the inductive magnetic excitation; and determining the likely distribution of magnetic sources on the surface of the hull by resolving a system of equations derived from modeling the physical phenomena at play, on the basis of the plurality of measurements taken and the assessed inductive magnetic excitation. The model describes the induced magnetic sources as a distribution of dipolar sources and the remanent magnetic sources as a distribution of monopolar sources. A device (6) for determining the magnetization of the hull of a ship for implementing the method is also described.

Abstract: In various embodiments, apparatus and methods of operating the apparatus are provided to determine existence and location of parasitic stress threes on a rod portion, the rod portion made of a magnetostrictive material and having a hollow tube. The apparatus may include a device comprising an envelope made of a non-magnetic material, a magnetic field source disposed inside the envelope, a motor to set the magnetic field source in rotational motion on the inside of the envelope, and a sensor to measure a value of the magnetic field and to deliver a signal representative of the value of the magnetic field. Operation of the apparatus may include penetration of the envelope into a portion of the hollow tube of the rod portion and translation of the envelope along the portion of the hollow tube. Additional apparatus, systems, and methods are disclosed.

Abstract: The present invention relates to methods for determining the existence and location of parasitic stress-inducing forces on a substantially cylindrical rod portion defined along a first axis and when this rod is made of a magnetostrictive material. The method according to the invention is essentially characterized in that it consists in magnetizing the wall of the rod portion in a pseudo-helix 10 centered on the first axis, in applying a forced stress between the two ends of the rod portion, in measuring, along the rod portion, the magnitude of the magnetic field created by the rod portion after it has been subjected to the forced stress, these measurements being taken in a direction substantially parallel to the first axis, and from these measurements, in deducing the existence and location of the parasitic stress-inducing forces on the rod portion. The invention also relates to a device for implementing this method.

Abstract: The invention concerns the methods for determining, relative to a point Po, the location of a fixing point Pf of a rod T located in an environment Mi wherein prevails a permanent magnetic field Ch. The inventive method is characterized in that it consists in studying the variations of the magnetic flux which passes through the windows F when the rod is and is not subjected to a torque about its axis A, said windows having substantially the same area and being connected to the rod T respectively in different points Px, Px+1, . . . located on the portion of the rod delimited by the assumed site of the fixing point Pf, and including the point Po, and having each a given position relative to the magnetic field lines of force when the rod is not subjected to the torque. The invention also concerns a device for implementing said method. The invention is advantageously applicable to determining the location of the sticking point of a string of hollow drill rods in an oil well.

Abstract: Various embodiments comprise a probe for analysis of a collection of rods or tubes, including an elongated casing which bears, at a first end, at least one first magnetometer and, at a position sufficiently remote from the magnetometer, a permanent magnet, the north-south axis of which may be perpendicular to the axis of the rods. Additional apparatus, systems, and methods are disclosed.

Abstract: The invention concerns a probe for analysis of a collection of rods or tubes comprising an elongated casing which bears, at a first end, at least one first magnetometer and, at a position sufficiently remote from the magnetometer, a permanent magnet, the north-south axis of which is perpendicular to the axis of the rods.

Abstract: The invention concerns the methods for determining, relative to a point Po, the location of a fixing point Pf of a rod T located in an environment Mi wherein prevails a permanent magnetic field Ch. The inventive method is characterized in that it consists in studying the variations of the magnetic flux which passes through the windows F when the rod is and is not subjected to a torque about its axis A, said windows having substantially the same area and being connected to the rod T respectively in different points Px, Px+1, . . . located on the portion of the rod delimited by the assumed site of the fixing point Pf, and including the point Po, and having each a given position relative to the magnetic field lines of force when the rod is not subjected to the torque. The invention also concerns a device for implementing said method. The invention is advantageously applicable to determining the location of the sticking point of a string of hollow drill rods in an oil well.

Abstract: The present invention relates to methods for determining the location of the sticking point Pc of a hollow rod or pipe 1 located in a shaft 30 subjected to the Earth's magnetic field, the point Pc being located in a part 3 defined between two points H and B of the pipe. The method according to the invention is essentially characterized in that it consists in continuously performing via the inside 2 of pipe 1, a first measurement of the magnetic field inside the part 3 of the pipe, by indexing it relative to the distance to one of the two points H and B, in applying a mechanical stress to the pipe at one of the two points H, B, in performing a second measurement of the Earth's magnetic field inside the part 3 of the pipe, by indexing it relative to the distance to one of the two points H and B, and in comparing the results R1-R2 of the two measurements in order to determine the location of the point Pc. The invention also relates to a device for implementing this method.

Abstract: The invention concerns a probe for analysis of a collection of rods or tubes comprising an elongated casing which bears, at a first end, at least one first magnetometer and, at a position sufficiently remote from the magnetometer, a permanent magnet, the north-south axis of which is perpendicular to the axis of the rods.

Abstract: The present invention relates to methods for determining the existence and location of parasitic stress-inducing forces on a substantially cylindrical rod portion 1 defined along a first axis 2 and when this rod is made of a magnetostrictive material. The method according to the invention is essentially characterized in that it consists in magnetizing the wall of the rod portion in a pseudo-helix 10 centred on the first axis 2, in applying a forced stress between the two ends 3, 4 of the rod portion 1, in measuring, along the rod portion, the magnitude of the magnetic field created by the rod portion 1 after it has been subjected to the forced stress, these measurements being taken in a direction substantially parallel to the first axis 2, and from these measurements, in deducing the existence and location of the parasitic stress-inducing forces on the rod portion 1. The invention also relates to a device for implementing this method.

Abstract: The invention concerns the field of devices and appliances for measuring the intensity and the direction of the magnetic field emitted by a plate or a structure, such as for example a ship's hull and it particularly concerns a method for determining the magnetisation and the magnetic field radiated by a ferromagnetic plate using magnetic field sensors distributed along said plate and at known positions relative thereto.

Abstract: The invention concerns the field of devices and appliances for measuring the intensity and the direction of the magnetic field emitted by a plate or a structure, such as for example a ship's hull and it particularly concerns a method for determining the magnetisation and the magnetic field radiated by a ferromagnetic plate using magnetic field sensors distributed along said plate and at known positions relative thereto.