Abstract: A remote non-invasive current sensing apparatus for sensing current being carried through a conductor located beneath or on top of a surface. First and second magnetic field sensor elements are placed in operative connection with the surface. There is no requirement to insert the sensor element within the current line by cutting the line or to encircle/enclose the conductor within a coil or other element. The second magnetic field sensor is located a predetermined distance from the first magnetic field sensor. The outputs of the magnetic field sensors are amplified and then provided to a processor which calculates the amplitude of the current in the conductor and the distance of the conductor is from the surface.

Abstract: In mutually opposite directions, two light signals traverse an optical series circuit including a first multi-mode fiber, a first polarizer, a Faraday sensor device, a second polarizer and a second multi-mode fiber. An intensity-normalized measuring signal is derived with the aid of direct signal components from light intensities of the two light signals after traversal of the series circuit.

Abstract: A magnetic measuring apparatus measures, at a high spatial resolution, a magnetic field generated by a current flowing in one of a plurality of highly packed parallel wires on a printed-circuit board. The magnetic measuring apparatus includes a magnetic field detector for detecting a magnetic field generated by a current flowing in one of a plurality of parallel wires, a measuring unit for measuring a magnetic field intensity based on an output signal from the magnetic field detector, an input unit for entering a pitch of the parallel wires and a spatial resolution characteristic of the magnetic field detector, a processor for calculating a height of the magnetic field detector from the one of the parallel wires based on the pitch of the parallel wires and the spatial resolution characteristic, and a scanning device for scanning the magnetic field detector into a position determined by the processor.

Abstract: A method and apparatus capable of detecting a considerably high voltage of a power supply while preventing an increase in the size and cost of circuitry, an increase in the amount of heat being generated, and a reduction in the detection accuracy of the circuitry. The voltage of a power supply to be detected is divided by way of a voltage-dividing resistor array. An voltage-to-current converter converts a potential difference appearing across the second voltage-dividing resistor in the array into a primary current so as to correspond to the potential difference. The converted primary current flows through a primary winding and an energization resistor. A second magnetic flux develops in a magnetic core from a secondary current, which flows through the secondary winding from a current buffer on the basis of the voltage output from a hole element according to the primary current.

Abstract: An electro-optic voltage sensor comprises a voltage divider connected to an electric line and to ground and having two insulative compartments separated by an intermediate electrode connected to a Pockels cell. The intermediate electrode supplies to the Pockels cell a reduced voltage derived from the voltage supplied by the electric line to the voltage divider. Each insulative compartment comprises a homogeneous dielectric block with a thickness dependent on the division ratio of the voltage divider. The electro-optic voltage sensor has a very high safety level vis a vis the risk of strong short-circuits combined with mechanical and thermal stability guaranteeing great accuracy of operation and great reliability without special maintenance requirements.

Abstract: A bidirectional current sensor including a transformer having a primary winding arranged in a circuit likely to be run through by a current to be measured, a secondary winding, an impedance for demagnetizing the transformer, and a measuring resistor connected to the secondary winding via a switch controlled to be on when a current is likely to run through the primary winding. It applies in particular to the detection of currents in bidirectional voltage converters.

Abstract: A device for non-contact, non-invasive measurement of current or power in a wire, cable or conductor includes a small coil having multiple turns and no ferromagnetic core. The coil may be secured to a wand or housing adapted to be used to place the coil in close proximity to the wire, cable or conductor, whereby a voltage is induced in the coil. An amplifier may be utilized to increase sensitivity. A readout indicates the magnitude of the induced voltage, and a scaling device renders the readout display indicative of the current or power in the wire, cable, or conductor. To measure direct current flow, the coil may be vibrated or rotated adjacent to the conductor to cause the magnetic field to induce a voltage in the coil. The readout may comprise a digital display, a series of light emitting devices, or a flashing light emitting device having a flash rate proportional to the magnitude of the voltage. The device may be constructed in a wand or pen-like fashion, with the coil incorporated into the wand.

Abstract: A connectionless signal detection device for conductive cables contains one or more bifurcated, wire-wrapped magnetic core assemblies positioned axially in an elongated alignment channel, allowing the device to accurately detect the transmission of signals or information on conductive cables using an inductive method. Each assembly section of the magnetic core assembly is wrapped with a conducting wire, with opposed assembly sections electrically connected in a bucking configuration, that is, the output side of one assembly section is connected to the output side of the opposing assembly section. The assembly sections either mate directly at their intersections or alternately operate with a dual gap. The elongated alignment channel opens and closes to allow positioning of the magnetic core assemblies concentrically about a conductive cable.

Abstract: An alternating current sensing apparatus includes at least two coils, each having a plurality of turns of wire around a core which defines a linear axis. The coils are mounted in spaced relation on a support surface so as to define an intermediate space, and the coils are electrically coupled additively in series. The coils produce a detectable signal in response to an alternating electrical current passing through a conductor which extends through the intermediate space.

Abstract: Radio-interrogated surface-wave technology sensor, in which the sensitive element (12) is an impedance which is electrically connected as termination to a surface-wave structure (26) of the sensor.

Abstract: A current-compensated current sensor for hysteresis-dependent and temperature-dependent measurement of even relatively large currents at different frequencies, includes a soft-magnetic magnet core having a flat magnetization loop. The sensor thus also permits rapid changes in a primary current to be measured.

Abstract: A method and a device for detecting and correcting a saturated current profile of a current transformer in a particularly simple and reliable way, initially uses a number of logic inquiries derived from sampled values of the present current signal profile to detect a start of saturation on the basis of a pattern recognition. An end of saturation is subsequently determined, likewise with the aid of a number of logic inquiries. A saturation signal is then formed from a combination of the logic inquiries. In the case of the detection of saturation, the current sampled values are discarded, and an image of the unsaturated current signal profile is reconstructed from a number of sampled values determined ahead of the time of detection of saturation.

Abstract: An integral meter and current transformer to measure single phase active and reactive energy, voltage and frequency in industrial, commercial and multi-family residential applications. The meter CT is the primary sensing element in a revenue metering system encompassing multiple meter CTs serially connected in groups in communication with data cores for collection and reporting of energy consumption. Numerous data cores may be networked to report to a central station which may be remotely interrogated over the network or dial up modem connection. The meter CT utilizes a split-core transformer with substantially overlapping fingers. Disengaging split-core sections of the meter CT enables it to be easily installed around a loaded conductor without the interruption of power to the load.

Abstract: A multimeter having an elongated housing with a fixed recess for receiving a current-carrying conductor is provided. The multimeter is adapted to measure various parameters including a.c. and d.c. voltage, resistance, and a.c. current. On one end of the elongated housing of the multimeter is a C-shaped current sensor mounted around the fixed recess for measuring a.c. current in the current-carrying conductor and on the other end is a pair of test leads for measuring resistance, a.c. voltage, and d.c. voltage. The current sensor and the test leads provide input signals to an analog-to-digital converter (ADC) to obtain digital samples which are displayed as measurement results according to the selected measurement mode.

Abstract: The present invention is a current sensing method and apparatus wherein a current transformer producing a secondary current is disposed in communication with a conductor having a primary current desired to be sensed. A current analyzer in communication with the current transformer is adapted to estimate the primary current in the conductor based on the secondary current output waveform, even in the case where the secondary current is in saturation. In one embodiment, the current analyzer estimates the primary current in the conductor by capturing the secondary current waveform output from the current transformer, selecting a predetermined number of data points in an undistorted, region of the secondary current waveform, and estimating the primary current based on the selected data points.

Abstract: An electricity measurement apparatus includes two spaced-apart parallel conductors through which current flows in the same direction inducing a magnetic field between the conductors. Two magnetic field sensors are disposed on each side of a first plane in which the conductors lie. The sensors are in a second plane that is substantially between the conductors and perpendicular to the first plane. An arithmetic processor processes signals from the sensors to provide a value representative of current flow. The provided value is substantially independent of the position of the second plane within the space between the conductors.

Abstract: Two light signals pass, in opposite directions, through a series circuit comprising a first optical fiber, a first polarizer, a Faraday sensor device, a second polarizer and a second optical fiber. To set the working point, additionally, the planes of polarization of both light signals are reciprocally rotated by a predetermined angle of rotation by rotation means between the two polarizers. From light intensities of the two light signals, after passing through the series circuit, a measuring signal is determined which is independent of vibrations and bending influences in the optical fibers.

Abstract: A magnetic core for a hybrid non-contact current meter having a magnetic core that is adapted for encircling a current carrying conductor wherein the magnetic core includes a first portion having a first integral toroidal section and a first pair of opposing side walls extending therefrom, a second portion having a second integral toroidal section and a second pair of opposing side walls extending therefrom such that the first portion and second portion are coupled together so to define an aperture between the first and second pairs of opposing side walls. The first and second integral toroidal sections are designed so to be void of any discontinuities within the flow path of the magnetic flux and to have a circular shape so to promote a more thorough flux saturation whereby a reduction of zero errors results and more accurate current measurement are obtained.

Abstract: An electrical junction box includes an electrical circuit, a current sensor having a ferrite bead ring for generating a magnetic field according to a current flow in the electrical circuit and also having a Hall element for outputting a signal based on the magnetic field of the ferrite bead ring, and a connector section for mounting both the ferrite bead ring and the Hall element. The electrical circuit has a terminal inserted through the ferrite bead ring to extend toward an opposing connector associated with the connector section. Furthermore, the Hall element has an output terminal extending toward the opposing connector.

Abstract: A magneto-impedance element includes an amorphous wire having a spiral magnetic anisotropy. A dc-biased alternating current is supplied to the amorphous wire, whereby a voltage is produced between both ends of the amorphous wire. The amplitude of the voltage varies asymmetrically with a variation in an externally applied magnetic field. The magneto-impedance element is compact, and has a high sensitivity and a high response speed.

Abstract: A device for detecting low magnitude electrical currents includes a generally toroidally-shaped member made of magnetic material that provides an air gap, and a magneto-resistive device in the form of a bridge located in the air gap for sensing a current flowing through a conductor that passes through the member. In order to reduce damage due to overcurrents, the member has a portion of reduced cross-sectional area to cause saturation of the member. The device can be used in an earth leakage current detector.

Abstract: An improved magneto optical current transducer for measuring electrical current is taught that significantly reduces birefringence resulting from thermal transients and construction-induced stresses. The transducer includes a housing made of a material that readily transfers heat throughout itself. Inside the housing and surrounding the magneto optical material is a buffer made of a material that does not readily tranfer heat from the housing to the magneto optical material, but rather slows its transference to that material material. The buffer material has a thermal expansion coefficient that is preferably very close to that of the magneto optical material, so that when the magneto optical material responds to changes in its temperature by expanding or contracting, the buffer expands with it at very nearly the same rate to avoid stresses.

Abstract: A radio-interrogated, surface-wave technology current transformer for high/medium-voltage systems includes a magnetosensitive element connected to a surface-wave structure of a surface-wave configuration as a termination of the surface-wave structure. A response signal of the surface-wave configuration is information regarding current strength/direction and phase of the current instantaneously flowing through the system, which is evaluated by a ground station. By virtue of the radio transmission, there is no electrical insulation problem, and the use of a radio-interrogated surface-wave configuration makes that part of the overall current transducer which is at high potential into a passive element of the same.

Abstract: A method for determining electrical measurement variables (e.g. DC or AC voltages or currents, powers or resistances) without physically contacting a conductor (1) includes at least two coil systems (6) arranged at a distance from one another. The coil systems (6) are positioned in the electromagnetic field of the conductor (1). The coils (6) and/or an electrically conductive component (3) in the vicinity of the coils (6) are set into periodic mechanical oscillation for the determination of DC voltages and/or direct currents. Consequently, determination of electrical measurement variables is achieved without physically contacting an electrical conductor which cannot be completely surrounded.

Abstract: A current sensor for sensing alternating current in a current-carrying conductor includes a substantially C-shaped magnetic core having first and second ends with a gap therebetween. A current sensing element, which includes a microresonant element, is positioned proximate the gap between the first and second ends of the magnetic core such that the element oscillates when exposed to an alternating magnetic field. A biasing coil is attached to the micro-resonant element for carrying a bias current. The micro-resonant element resonates, or vibrates, at a standard oscillating frequency when no current is present in the biasing coil, and resonates at a modified oscillating frequency when current is present in both the biasing coil and the current-carrying conductor. The magnitude of current in the current-carrying conductor is determined as a multiple of the product of a ratio of the standard oscillating frequency and the modified oscillating frequency, and the bias current.

Abstract: The alternating current sensor has a transformer-like iron core structure, the circuit in which the current to be measured is connected to the primary winding (current input winding), the secondary winding includes two independent units, namely output current winding and exit measuring winding. The conductor for the output current winding is of high stability with low temperature coefficient of resistance. Nearly the entire induced current in the secondary side flows in the output current winding, finally the induced voltage in the measuring winding is detected by the voltage meter. By this scheme those disadvantages of the conventional alternating current sensor such as high temperature rise, resistance variation caused by increased temperature coefficient of the conductor and the load resistance effect are minimized to achieve the aim of high accuracy alternating current measurement.

Abstract: The measuring device is intended for a metal-enclosed, gas-insulated high-voltage installation. It contains at least one sensor (10, 11), arranged in an enclosure tube (3) of the metal enclosure which is filled with insulating gas, and at least one electronic evaluation device (23, 23'), which processes output signals of the sensor (10, 11). The evaluation device (23, 23') and a plug-and-socket device (28, 28') connecting the evaluation device to an output of the sensor (10, 11) are arranged in a two-part metal housing. One part of this housing is formed by a hollow metal flange (26), integrally formed on the outer surface of the enclosure tube (3), and the region of the enclosure tube (3) rimmed by the hollow flange (26). The other part of the housing is a housing element (27) which is depressed in the shape of a trough and is fastened to the hollow metal flange (26) of the enclosure tube (3) by its edge, which delimits the trough opening.

Abstract: Measuring devices for determining magnetic fields to be used in particular for the potential-free measurement of the strength of an electric current which generates such a magnetic field. To obviate the need for an intermediate element specially connected into the relevant current conductor and to allow the measurement device instead to be accommodated in a clamp device which needs only to be slipped over the current conductor, the proposed embodiment has two measuring bridges which are fixed on either side of the current conductor, the staggering of the two bridges is assessed from the current magnetic field via a control circuit.

Abstract: Two light signals pass through a series connection of a first multimode optical fiber, a first polarizer, a Faraday sensor device, a second polarizer an a second multimode optical fiber in opposite directions. The polarization axes of the two polarizers are set at a polarizer angle .eta. or .theta. to the natural axis of the linear birefringence in the sensor device with cos(2.eta.+2.theta.)=-2/3. The measuring signal is derived as the quotient of two linear functions of the light intensities of the two light signals after passing through the series connection.

Abstract: A cryogenic current comparator device is based on the magnetic shielding properties of superconducting tubes and maintains electrical currents being compared in a highly exact integer ratio. One pair of superconducting tubes are arranged adjacent to each other so that the longitudinal axis of each tube are parallel. A coil of current carrying wire is formed by winding the wire down through a longitudinal bore of the first tube and then back up the longitudinal bore of the second tube to form at least one turn or loop of the coil. A second, identical pair of superconducting tubes is placed adjacent and longitudinally parallel to the first pair of tubes so that a superconducting quantum interference device magnetometer is surrounded by the four tubes in order to measure a magnetic field induced by the current traveling through the coils. The device operates at a temperature of 77 degrees K.

Abstract: Linearly polarized measuring light is broken down into two differently polarized component light signals in an analyzer after passing through a Faraday sensor device. The intensity of the corresponding electric intensity signals is normalized by dividing the respective alternating signal component by the respective direct signal component. From the two normalized intensity signals S1 and S2, a measuring signal is derived according to the formula:S=(2.multidot.S1.multidot.S2)/((S2-S1)+K.multidot.(S1+S2))where cos(2.theta.+2.eta.)=-2/(3K) and sin(2.theta.-2.eta.)=1 are valid for a correction factor K, an injection angle .eta. between the plane of polarization of the injected measuring light to a natural axis of the linear birefringence in the sensor device and a exit angle .theta. between this natural axis and a natural axis of the analyzer.

Abstract: A device for optically measuring a physical quantity in power equipment includes an optical fiber associated with the power equipment, an optical part for transmitting/receiving light to/from the optical fiber, calculation unit for calculating a physical quantity in the power equipment by detecting the polarized state of light polarized by the power equipment on the basis of the output from the optical part, a housing box for housing the optical part, and a fixing member to which the optical part is mounted and which is fixed to the housing box by laser welding.

Abstract: Method and system for measuring an electric current in a current conductor, two opposing light signals are transmitted through a Faraday element surrounding the current conductor and, after the passage through the Faraday element, are split, respectively, into two partial light signals. From these partial light signals, an intensity-normalized signal is derived for each partial light signal. Provision is made of a Faraday element having a negligible circular birefringence, and a signal processing unit for deriving a vibration-independent and temperature-independent measured signal.

Abstract: An electrical device is capable of sensing both AC and DC current which is flowing through an electrical circuit. The electrical device bifurcates the current into separate paths, wherein impedance of each path has a constant relationship to each other. In a further embodiment, the electrical device includes a current sensor for measuring current flowing through the circuit. The sensor is of a type which does not introduce insertion loss.

Abstract: Simple methods for magnetooptic current measurement and magnetooptic current-measuring devices are specified, which are independent of temperature influences on the measurement result and require no compensation device for the light intensity of light sources (LD1, LD2) employed. Light beams (1, 2) from the two laser light sources (LD1, LD2) are alternately polarized orthogonally relative to one another by means of a beam splitter (3), and are transmitted to light detectors (D.sub.A, D.sub.B) via collimators (4, 6), which are connected via a polarization-maintaining high-index birefringent HI fiber (5), through a magnetooptic current sensor (7), an analyzer (10), 2 collimators (11, 12) and multimode fibers (13) and (14). 1st and 2nd light output signals S.sub.A1 and S.sub.B1 as well as 3rd and 4th light output signals S.sub.A2 and S.sub.B2 are derived sequentially in time from the light detectors (D.sub.A, D.sub.B).

Abstract: An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

Abstract: Inductive current sensor and electrical apparatus incorporating this sensor. The magnetic circuit of the sensor comprises a separable part carrying the detector element and is made of a material having a permeability lying between 5 and 100. The circuit reduces the influence of spurious gaps and external interference on the current sensor for the electrical apparatus.

Abstract: An improved isolated current sensing device. The invention consists of two magnetizable cores which surround the conductor carrying the current to be measured. The two cores are cyclically saturated in opposite directions by a high-frequency excitation current counter-wound around the two cores. The device then detects through an output winding the asymmetry in the core magnetic fluxes caused by the current-carrying conductor. The output signal is passed through a phase-sensitive detector tuned to twice the original excitation frequency. Negative feedback is used to stabilize the device.

Abstract: A current determiner having an output at which representations of input currents are provided having an input conductor for the input current and a current sensor supported on a substrate electrically isolated from one another but with the sensor positioned in the magnetic fields arising about the input conductor due to any input currents. The sensor extends along the substrate in a direction primarily perpendicular to the extent of the input conductor and is formed of at least a pair of thin-film ferromagnetic layers separated by a non-magnetic conductive layer. The sensor can be electrically connected to a electronic circuitry formed in the substrate including a nonlinearity adaptation circuit to provide representations of the input currents of increased accuracy despite nonlinearities in the current sensor, and can include further current sensors in bridge circuits.

Abstract: A bus bar structure which can detect current exceeding the rated allowance of the current sensor and which does not involve insertion of the bus bar, thereby increasing the current sensor detection range, reducing the cost of manufacture due to downsizing of the magnetic core, improving the degree of freedom in the arrangement of the bus bar, and improving the operability of assembling the current sensor to the bus bar. The bus bar structure includes: an electrical junction box (21) to be mounted on a motor vehicle; a bus bar (37) arranged on the electrical junction box (21), the bus bar (37) serving as a bus bar from which to detect current; a current sensor (23) that is mounted on the electrical junction box (21); and a shunt bus bar (31) that is integrally formed with the current sensor (23) while passing through a magnetic core of the current sensor (23).

Abstract: A method and sensor for accurately measuring DC current includes an electromagnetic circuit component, such as a current transformer, having a saturated state and an unsaturated state which generates a DC current based on the DC current being measured. The current transformer includes a first circuit for generating the DC current being measured. A second circuit is electromagnetically coupled to the first circuit to generate a constant DC offset current so as to minimize error at low levels of the measured DC current. A third circuit is electromagnetically coupled to the first circuit for generating a third DC current representative of the first DC current. The first DC current is then measured based on the third DC current. The measured first DC current is then adjusted based on the added second DC current. A sampling circuit is operatively coupled to the third circuit component for sampling the third DC current during a sampling interval.

Abstract: Current is sensed by a circuit which provides a high frequency reversing voltage to a sensing winding on a current transformer, for driving the transformer into its linear region at least once per high frequency cycle. Current through the sensing winding is sampled while the transformer is in that linear region. Preferably, the current is sampled approximately at the instants of reversal of the voltage being applied to the sensing winding, and the sample having the lower absolute value is selected as a sample proportional to the line current.

Abstract: A polarized measuring light is provided to a sensing means under the influence of an alternating electrical quantity, the polarization of the measuring light changing as a function of the alternating electrical quantity. After passing through the sensing means, the measuring light is split into two differently polarized partial light signals, which are then converted into electrical intensity signals S1 and S2. An intensity-normalized signal P=(S1-S2)/(S1+S2) is then formed. A temperature-compensated measured signal can then be derived from the alternating signal component PAC and the direct signal component PDC of the intensity-normalized signal according to the equation S=(a*PAC+b*1)/(c*PDC+d*1). The temperature sensitivity can thus be reduced by a factor of ten.

Abstract: A faulted indicator elbow-type termination connector for indicating the occurrence of a fault current in an electrical conductor of an alternating current distribution power system includes means for producing a magnetic field in response to an applied current to the electrical conductor. The termination connector includes a cylindrical body portion having a recessed housing section which projects radially from a central axis thereof. A faulted circuit indicator module is rotatably mounted within the recessed housing section and contains a trip setting device which is responsive to the magnetic field. The trip setting device has its sensitivity adjusted by rotating the faulted circuit indicator module relative to the cylindrical body portion. As a result, the sensitivity of the trip setting device can be changed quickly and easily so as to accommodate various trip settings.

Abstract: A measuring device for measuring time varying differential-mode currents flowing in first and second conductive groups includes a low reluctance magnetic circuit including first and second portions defining first and second openings positionable to surround the first and second conductive groups. The magnetic circuit comprises a twisted loop which cancels common-mode flux produced by common-mode current flowing in the first and second conductive groups.

Abstract: A remote non-invasive current sensing apparatus for sensing current being carried through a conductor located beneath or on top of a surface. First and second magnetic field sensor elements are placed in operative connection with the surface. There is no requirement to insert the sensor element within the current line by cutting the line or to encircle/enclose the conductor within a coil or other element. The second magnetic field sensor is located a predetermined distance from the first magnetic field sensor. The outputs of the magnetic field sensors are amplified and then provided to a processor which calculates the amplitude of the current in the conductor and the distance of the conductor is from the surface.

Abstract: A magnetic core for a non-contact clamp-on current sensor having a magnetic core that is adapted for encircling a current-carrying conductor wherein the magnetic core includes a first portion having a first integral toroidal section and a first pair of opposing side walls extending therefrom, a second portion having a second integral toroidal section and a second pair of opposing side walls extending therefrom such that the first portion and second portion are coupled together at the first and second pairs of opposing side walls so to define an aperture therebetween for receiving a current carrying conductor and measuring the line current therein. The first and second integral toroidal sections of the magnetic core are designed so to be void of any discontinuities within the flow path of the magnetic flux and so to have a circular shape which promotes a more thorough flux saturation.

Abstract: An apparatus for measuring the dc current in a power supply circuit includes a transformer having a primary winding, a core and a secondary winding, a current generator, a pulse generator, and a measurement circuit. The secondary winding of the transformer is coupled to the power supply circuit, wherein the power supply circuit supplies dc current to the secondary winding generating a second field of magnetic flux. The current generator, coupled to the primary winding of the transformer, supplies an ac current to the primary winding generating a first field of magnetic flux. The pulse generator, coupled to the primary winding, generates a pulse when the first field of magnetic flux is substantially equal to the second field of magnetic flux. The measuring circuit, coupled to the current generator and responsive to the pulse generator, measures the ac current from the current generator in response to a pulse received from the pulse generator, wherein the ac current is proportional to the dc current.

Abstract: A sensor assembly for measuring current I.sub.o is disclosed. The sensor assembly includes four magnetoresistive resistors (1, 2, 3, 4) arranged to form a Wheatstone bridge. The bridge is disposed over a U shaped conductor 14. The resistors are arranged so that two resistors (1,2) forming one bridge branch are disposed over one leg of the conductor and the two resistors (3,4) forming the other bridge branch are disposed over the other leg of the conductor. Each resistor is formed out of a number of magnetoresistive strips (1', 2', 3', 4'). The magnetoresistive strips forming the individual bridge branch resistors are interleaved so as to ensure the resistors forming each bridge branch have substantially the same temperature. When current I.sub.o is applied to the conductor, the equal and opposite magnetic fields that develop around the individual bridge branches cause the Wheatstone bridge to produce a signal U.sub.a that is a function of the current.

Abstract: A portable current measuring apparatus brings many current sensing devices close to a wire in order for the magnetic flux of the current within the wire to induce a current in the devices. The devices are arranged in a bridge circuit and connected with a signal source and a differential amplifier so that when the output of the devices is added by the amplifier the noise generated by magnetic sources is eliminated. The housing for the apparatus is small and light weight and includes a place for a portion of the current carrying wire to be positioned for current detection. Use of the apparatus does not require that the wire be cut, nor is it required that the apparatus become a permanent fixture of the circuit having the current carrying wire.