Abstract: A fault indicator for three phase sheathed cables includes a flexible collar unit which fits over the cable. Magnetic pole pieces within the collar unit having associated magnetic windings are aligned with the three conductors within the cable to produce signals indicative of the current level in each conductor. An alarm unit receives the signals and sounds an alarm in the event the current in any conductor exceeds a predetermined threshold level to indicate the occurrence of a fault. The voltage level of the current indicating signals may be utilized to align the magnetic core assemblies with the conductors.

Abstract: A method and a measuring device for determining the spatial distribution of a magnetic field vector. At least a pair of sensor elements is provided. Each sensor element measures a component of the magnetic field vector. The sensor elements are aligned in a parallel, spaced-apart relationship along an axis parallel to the measured components.

Abstract: Disclosed is a method of measuring axially symmetric magnetic fields. According to this method, an electric field generator or magnetic field generator for generating axially symmetric electric fields or magnetic fields is placed on a rotator. The rotator is used to change a rotational position of the electric field generator or magnetic field generator, that is, a specified sector thereof. Meanwhile, an electric field or magnetic field is measured.

Abstract: A device (16) for sensing current flowing in a generally flat plate structure (10) contains a magnetic head (18) and signal processing circuitry (20). The magnetic head (a) senses changes in current-induced magnetic flux as the head is positioned over the plate structure and (b) provides a head output signal. The signal processing circuitry processes the head output signal to produce a data signal indicative of how much current appears to flow in the plate structure below the head. A driving voltage, which typically varies in a periodic manner to produce a characteristic signature, is applied to a primary conductor in the plate structure. A location sensor, typically formed with a light source (100) and a light sensor (102), detects the position of the magnetic head relative to the plate structure. A gas-cushion mechanism (80-98) controls the height of the head above the plate structure.

Abstract: A semiconductor device evaluation apparatus is provided with a test board. A print wiring is provided at a first surface of the test board on which a semiconductor device is mounted. A terminal of the semiconductor device is connected to the print wiring. A power circuit is provided at a second surface opposite to the first surface of the test board. The power circuit is connected to the print wiring and actuates the semiconductor device. The apparatus is also provided with a magnetic field detector arranged above the print wiring and detects a magnetic field generated from the print wiring. Further, the apparatus is provided with a current detector detecting a value of current carried through the print wiring based on the magnitude of the magnetic field detected by the magnetic field detector.

Abstract: An electromagnetic lock and status detection system and method therefor includes an armature, an electromagnet, and a status detection unit. The electromagnet is magnetically attracted to the armature into a mating relationship. A relatively high inductance is established in the electromagnet when the electromagnet is properly mated with the armature, and a relatively low inductance is established in the electromagnet when the electromagnet is not properly mated with armature. The status detection unit is coupled to the electromagnet to monitor the locking strength between the electromagnet and the armature. The unit monitors the locking strength by altering voltage level provided to the electromagnet and measuring the counter EMF induced in the electromagnet.

Abstract: A cathodic protection system utilizes dynamic control of an output from a power supply to vary an impressed current applied to a structure to be protected proportional to a measurement of stray electrical current. The current is also supplied to an anode bed in an amount sufficient to maintain the structure more negatively charged than the anode bed such that the stray electrical currents are directed away from the structure, thus avoiding electrolytic attack.

Abstract: A SQUID (Superconducting Quantum Interference Device) magnetometer, by far the most sensitive means for detecting small magnetic field variations, is utilized to detect defects inadvertently produced in the manufacture and draw-down of wires. Detection is effected by moving any electrically-conducting wire directly under a shielded SQUID magnetometer with a small aperture to permit the sensing of the magnetic field associated with injected or induced alternating electrical current. Shielding may be provided either by a mu-metal cylinder with a small concentric bottom hole or an open superconducting cylinder strategically placed around the SQUID sensor. Initially, the position of the cryogenic containment vessel (dewar) is oriented to produce a null magnetic signal at the squid sensor location. Any phase-sensitive-detected) signal that appears after wire is spooled under the sensor must be related to non-concentric deviations of the current path in the wire.

Abstract: An apparatus for detecting irregularities in a ferrous pipe includes a magnetizing coil for inducing a magnetic field in the ferrous pipe. Inspection sensors measure changes in the induced magnetic field and produce signals representative of those changes. An analog-to-digital converter digitizes the measured signals representing the changes in the induced magnetic field. A processor compares the signals to a threshold value, and, when a signal exceeds the threshold value, the processor stops the inspection process to locate an irregularity in the ferrous pipe. The processor further processes the signals according to frequency to classify the signals by type of irregularity in the ferrous pipe. A screen and/or printer displays the frequency processed signals according to type of irregularity in the ferrous pipe.

Abstract: A method of detecting the presence of an electric cable, the electric cable including conductive armoring and a conductive core that is electrically insulated from the armoring. In the method, the armoring is connected to ground, and a current pulse is emitted over the armoring by way of a current injector device connected to ground so that the return of the pulse to the injector device takes place via ground. The presence of the electric cable is detected in the proximity of a reception point by detecting, at the point, a signal that is representative of the pulse, by way of a detector.

Abstract: The present invention provides a circuit capable of operating according to a normal operating mode or to a structural operating mode. The test mode is stored in an internal flip-flop via an interface of the circuit. In test mode, the flip-flop is insulated from the interface by multiplexing means. To exit the test mode, an input temporarily dedicated to this function is used, this input being then insulated by multiplexing means from the rest of the circuit.

Abstract: A method and apparatus for testing a magnetic head provided with at least one MR transducer. The method includes a step of applying a sense current varying with respect to time to the MR transducer element via input/output terminals of the MR transducer element, and a step of measuring a terminal voltage across the input/output terminals of the MR transducer element to check varying resistance characteristics of the MR transducer element with respect to the variation of the applied sense current.

Abstract: To provide a nondestructive inspection apparatus with a reduced distance between a superconducting magnetic sensor and an object under inspection, a cryostat for cooling the sensor to a superconducting state is provided with inner and outer vessels. The inner vessel has a baseplate on which the magnetic sensor is disposed, and has an inner wall defining a central chamber for containing a refrigerant for cooling the magnetic sensor. The outer vessel has an inner wall defining a central chamber for containing the inner vessel, the magnetic sensor and the stage. A gap between the inner and outer vessels is evacuated to insulate the inner chamber from the ambient atmosphere. To facilitate ease of transferring an object to and from the stage for inspection, a load lock area is provided adjoining the outer vessel.

Abstract: A double tunnel junction is disclosed that can be used as a magnetic sensor or as random access memories. The preferred embodiment comprises three magnetic metal materials separated by two insulating layers. A current is passed through the first tunnel junction thereby developing a voltage in the second junction. The resistance of this device can be changed over a 100% when an external magnetic field of just a few gauss is applied.

Abstract: A magnetooptic device to be used in industrial applications to investigate articles for flaws or defects. The magnetooptic device is capable of revealing defects in articles of nonmagnetic and magnetic conducting material. These results are achieved by designing a magnetooptic device having a magnetooptic transformer element on its bottom surface and incorporating a front electrical contact and a rear electrical contact on the bottom surface of the MO device. The respective electrical contacts are connected by wire conductors to the respective positive and negative terminals of a source of electrical current. The defect pattern of an article can be either visually viewed or the defect pattern can be recorded on a tape or magnetic rubber sheet placed between the bottom surface of the MO device and the top surface of the article being analyzed.

Abstract: An apparatus and method for detecting anomalies in ferrous pipe structures is presented. An electrical current is passed through the ferrous pipe structure so as to create a magnetic field in the pipe. A sensor having one or more sensor shoe members is placed in the interior of a ferrous pipe structure to be inspected. Each sensor shoe member has one or more magnetometer elements for detecting the magnetic fields in the region of the ferrous pipe structure adjacent to which the sensor shoe member is placed.

Abstract: An apparatus for detecting irregularities in a ferrous pipe includes a magnetizing coil for inducing a magnetic field in the ferrous pipe. Inspection shoes measure changes in the induced magnetic field and produce signals representative of those changes. An analog-to-digital converter digitizes the measured signals representing the changes in the induced magnetic field. A processor processes the signals according to frequency to classify the signals by type of irregularity in the ferrous pipe. A screen and/or printer displays the frequency processed signals according to type of irregularity in the ferrous pipe.

Abstract: Inclusions such as encysted parasites and spoilage in food products such as fish fillets are detected by immersing the food products in a bath of an electrolyte, such as a saline solution, having substantially the same electrical conductivity as the uncontaminated food product. An electrical current passed through the electrolyte also passes through the food product. Perturbations in the resulting magnetic field produced by the discontinuities in conductivity at the boundaries of the inclusions or of the spoiled article which have substantially different conductivities from that of the electrolyte and unspoiled food products, provide an indication of the presence of the contamination. Production line inspection rates are achieved by conveying the food products through a container filled with electrolyte and past an array of stationary magnetometers.

Abstract: An apparatus and method for detecting anomalies in ferrous pipe structures is presented. An electrical current is passed through the ferrous pipe structure so as to create a magnetic field in the pipe. A sensor having one or more sensor shoe members is placed in the interior of a ferrous pipe structure to be inspected. Each sensor shoe member has one or more magnetometer elements for detecting the magnetic fields in the region of the ferrous pipe structure adjacent to which the sensor shoe member is placed.

Abstract: The wireless shipboard data coupler allows transmission of data through steel ship bulkheads and submarine pressure hulls without the need for special wiring penetrations. Shipboard sensing data with a 1.0 MHz current is injected into the steel plating adjacent to a ships bulkhead, or onto the pressure hull at any penetration providing an electrical path or discontinuity to the opposing side of the bulkhead or pressure hull through the use of copper-plated, threaded electrodes. The injected current flows as a surface, or "skin effect" current between the electrodes and in an indirect, spread, pattern wrapping around the edge of the penetration. This produces a pattern of surface currents on the opposite side of the ships bulkhead or submarine pressure hull. As the injected current is modulated, the data is received on the other side of the bulkhead or pressure hull using coupling loops to sensing the electrical field generated by the surface currents.

Abstract: A method for examining an edible product, such as fresh fish flesh, for dielectric inclusions, such as encysted parasites. The product is subjected to a current flow, which may be perturbed or deviated by any hidden inclusions. An electromagnetic effect of perturbed current flow is detected. In a preferred implementation, one or more scans of the external magnetic consequences of the effect of an inclusion allows the discovery and removal of the inclusion.

Abstract: This invention relates to an apparatus and method for measuring the resistance of superconductors. Structures of this type, generally, allow the resistance of the superconductor to be accurately measured in a non-destructive manner by using a bifilar coil which includes an integrated loop/switch formed from the bifilar coil.

Abstract: A device for measuring the position of a conductor in an enveloped cable, preferably directly after extruding the plastic envelope, in which at least a supporting means for a sensor is continuously engaging the periphery of the envelope and in which the sensor determines the distance between the conductor and the sensor, and wherein the output signal of the sensor is delivered to a processing and displaying means, wherein the supporting means is defined by a roller driven by the cable which roller is yieldingly supported normal to the rotational axis.

Abstract: A process for mapping the path of an electric arc through a sample of resive material whereby the magnetic field propagated by the arc is recorded on a sleeve of magnetic sensitive material which surrounds the sample, with the intensity of the recorded field at different points on the sleeve indicating the path of the arc.

Abstract: Electrical current distribution in the soil surrounding a buried pipeline is detected by applying an AC electrical potential between the pipe and a buried electrode spaced from the pipe. The magnetic field at spaced localities along the pipe arising from currents transverse to the pipe is detected. Additionally, a potential containing a plurality of alternating frequencies is similarly applied to the pipe and the magnetic field induced by the resulting electrical current both along the pipe and transversely of the pipe is detected. The magnetic field is detected by correlation discrimination at spaced locations along the pipe and across the spectrum of the impressed frequencies. The detected data is used to determine the capacitance and resistance of the soil/pipe interface at localities along the pipe and to generate impedance plots which indicate characteristics of that interface.

Abstract: Flaws in an electrically conductive sample object are detected by cancelling the magnetic field generated by a detection current passed through the sample object by passing the current back through an unflawed field cancelling object placed next to the sample object, and measuring the uncancelled field produced by any flaw, preferably with a superconducting quantum interference device (SQUID) magnetometer. Elongated objects such as tubes and rods are fed through a sleeve which forms the field cancelling object, with the current applied to the elongated member and passed to the field cancelling sleeve through sliding contacts.

Abstract: Disclosed is an organic material with a very narrow electronic spin resonance (ESR) line. This material is formed by a 1, 2, 7, 8-tetrahydrocyclopentataperylene salt which may have, advantageously, undergone a heat treatment. The material can be applied to the fabrication of probes for gaussmeters and magnetometers.

Abstract: An array of SQUID detectors to map the magnetic field associated with test currents flowing in the component to be tested. The SQUID is an ultrasensitive, miniature device that transduces a faint magnetic field to a measurable voltage. Perturbation occurs in the test currents and the associated magnetic field at physical defects or inhomogeneities. Multi-dimensional test currents are injected into the component being tested; the injection being made between specific electrodes by varying the direction of the current until it is normal to the direction of the defect to maximize and amplify the effect of the perturbation. The perturbation is detected by the SQUID grid which pinpoints the location, orientation, and size of the defect. The frequency of the injected current can be made to sweep the spectrum from DC to the highest response limit of the SQUID to scan for defects at various depths.

Abstract: A process is provided for transmitting a signal, without material connection, through a conducting wall which may be a ship's hull, to external user apparatus.A current supplied by a generator and whose intensity is proportional to the amplitude of the signal to be transmitted is applied between two points on the hull. The magnetic field variations generated by the passage of the current are detected by a sensor on the other side of the hull and, suitably amplified, are used for controlling an apparatus.

Abstract: An apparatus is provided for measuring the test current in magnetoelectric fault detection, for instance by the magnetic particle method. A sensor comprising a Hall generator or a magnetoresistor is movably mounted on a diamagnetic support which clamps the sensor at a variable distance from a conductor carrying the test current. Alternatively, a plurality of sensors can be fixed to the support and the appropriate sensor selected for use.

Abstract: A method and an apparatus for detecting defects in the surface of a metal material relying upon the potential drop method. Namely, a method of precisely determining the shape of crack from a distribution of potential differences in the vicinity of crack by arranging power supplying electrodes and measuring electrodes on the surface of the metal material in the form of a matrix, and switching the electrodes that supply electric current and the electrodes that measure potential differences to measure distributions of potential differences in many directions, and an apparatus for detecting surface defects relying upon the potential drop method. In the apparatus for detecting surface defects, the arrangement of power supplying electrodes and supply currents are optimized to precisely detect the shape of crack in the surface.

Abstract: A method of investigating the condition of biological particles, in particular the fraction of viable cells in a bacteria population involves applying a voltage and monitoring the voltage induced by magnetic induction in a detector coil. The applied voltage is of a variable frequency alternating voltage and is preferably induced in the medium through a drive coil.

Abstract: A single mode optical fiber is used to detect electrical currents or magnetic fields from a source to a high degree of accuracy. Phase modulation of an optical beam is used to determine the changes of physical properties of a magnetostrictive material which jackets the fiber or around which the fiber is wound. An electromagnetic field, such as that emanating from a high intensity field wire, is measured by the device which acts as a current transformer and meters peak-to-peak electric currents of approximately 10,000 amperes or more with accuracy exceeding 0.1%. The invention structure of the device provides advantages such as operation safety, EMI immune leads, low cost, light weight, and dielectric construction among others.

Abstract: A method and apparatus for determining the shielding effectiveness of an RF gasket installed between two mating metallic surfaces of equipment or a structure by creating a time varying current flow from one of the mating surfaces to the other across the RF gasket, and sensing the current density of the time varying current in the vicinity of the gasket as a measure of shielding effectiveness. Two spaced electrodes, in the form of circular metal discs with a layer of dielectric material, are placed adjacent and substantially parallel to respective ones of the two metallic surfaces mated by the RF gasket with the gasket lying in the space between the electrodes. The electrodes are arranged to capacitively create a time varying current flow in the mating metallic surfaces between the electrodes. The current density in the metallic surfaces is sensed at a fixed position between the electrodes as a measure of gasket shielding effectiveness.

Abstract: Resistance faults, for example across insulating joints of cathodically protected pipelines may be evaluated by comparing magnetic field strengths associated with a test current of predetermined frequency flowing into and away from the joint.

Abstract: A magnetic materials separator including an axially inclined drum disposed for axial rotation within the curvature of an arcuate magnet structure which extends axially of the drum and is disposed in close-spaced relationship with the outer surface of the drum. The magnet structure comprises an axially extending series of arcuate magnet yokes, each comprising an axially laminated array of arcuate magnet sub-assemblies which are alternately polarized in opposite axial directions. Each of the sub-assemblies comprises an arcuate magnet axially polarized and sandwiched between a arcuate pair of soft magnetic flux concentrators which have respective axial thicknesses between five and twenty percent of one-half the axial thickness of the sandwiched magnet.

Abstract: A method for monitoring structures by measuring electrical quantities including subjecting an electrically conducting component to an a-c current with a predetermined frequency in a given direction generating a magnetic flux in a given direction, tapping a voltage drop across two measurement points mutually spaced apart by a given distance at individual partial regions of the component with two measuring lines contacting the component, forming a first conductor loop from the measuring lines and the component with an inductively effective area being as small as possible, forming a second conductor loop being substantially parallel to the given direction of the current and perpendicular to the given direction of the magnetic flux, tapping an induction voltage from the change of the magnetic flux as close as possible to the measuring points with the second conductor loop, feeding the voltage drop and the induction voltage to an electronic evaluation circuit, and deriving the local resistance of the component at

Abstract: To determine the relative positions of two bodies, an alternating current is passed through a conductive path in the first body, establishing an alternating magnetic field around the body, the amplitude of the field decreasing in inverse proportion to the distance from the conductive path. Coil pairs are supported on a second body so as to essentially surround the first body, the coils being used to produce voltages proportional to the intensity of the magnetic field, thereby providing differential distance information. The voltage differences of the coils can be used for establishing the shape of the first body or for positioning the second body to a coaxial location of the coil pairs with respect to the first body. The determination is largely free from interference.

Abstract: Methods and apparatus are disclosed for measuring a length of logging cable introduced into a borehole, thereby measuring the depth of a logging tool, or sonde, attached to the lower end of the cable. The methods involve producing an electrical signal, which propagates along the cable, and detecting at the mouth of the borehole the time of passage of the initial electrical signal and the time of passage of a subsequent electrical signal reflected or returned upwardly from the lower end of the cable, or, alternatively, the time of arrival of the reflected or returned electrical signal at the upper end of the cable. These times can be determined by means of clocks which are switched on by the passage of the initial electrical signal and switched off by the subsequent electrical signal. Knowing the time intervals and the velocity of propagation of electrical signals in the cable, the length of cable from the mouth of the borehole to the lower end of the cable, and thus the depth of the sonde, is measured.

Abstract: An automatic overhead trolley-driven magnetizing system for inducing a residual magnetic field in seamless steel pipe in order to detect non-visual defects therein by the magnetic particle inspection method is described. The magnetizing system consists of a trolley-driven magnetizing unit which moves on an overhead runway until a retractable limit switch causes the unit to stop upon reaching the trailing end of the pipe, an electrical contact pad then lowers onto the surface of the pipe, and introduces a magnetizing current to the pipe sufficient to cause magnetic particles deposited on the pipe surface to indicate the location of defects in the pipe. The magnetizing system is arranged to remain remote from the manufacturing flow path of the workpiece until the magnetization thereof is required.

Abstract: The invention is a resonant circuit sensor of physical properties of objects that monitors measurable properties of resonant circuits affected by interactions of the objects with the polarized, resonant oscillations of the circuits. The circuits can be passive with excitation by an external energy source or active with a source included as an integral part. Simultaneous or sequential sensing of more than one physical property of objects is obtained by detecting resonant oscillation characteristics such as amplitude, frequency, phase or polarization and by detecting quantities influenced by such characteristics for one or more orientations of the objects relative to the polarization of the oscillations. These resonant oscillations can be in the form of electromagnetic fields, electric fields, magnetic fields, or acoustic waves.

Abstract: A pair of electrical prods along with a powder supply gun are incorporated in a single portable frame member which is easily insertable into a relatively small blind bore; prod tension against the bore wall is adjustable by varying spring plunger tension; incorporated in the apparatus is the ability to locate indications in all directions by provision of both linear and axial heads which interchange on the same frame or handle; powder is applied to the area to be inspected while current is flowing into the prods, and the powder gun can be rotated and retracted as required to provide full coverage of the area to be inspected with powder.

Abstract: A method and apparatus for detecting flaws in conduits or the like which prises positioning an annular array of Hall-effect devices transversely around the conduit, applying an electric current to the conduit to flow longitudinally therethrough so as to create a magnetic field around the conduit, sequentially scanning the Hall-effect devices to produce a series of output signals corresponding to the portions of the magnetic field sensed respectively by them, and comparing the output signals for nonuniformities among them, the nonuniformities being indicative of the existence and location of flaws.