Abstract: A current sensor employs a folded conductor bar having aligned holes therein to generate magnetic fluxes in the holes proportional to a current flowing in the bar. Each of the two holes has two windings therein wound in opposition to each other but connected for adding their voltages. Corresponding windings in the two holes are wound in opposition to each other and are connected for adding their voltages. The windings in each hole are offset from a center line, whereby magnetic fluxes generated by current flowing in the bar induce voltages in the coils but magnetic fluxes from external sources produce voltages which substantially cancel. A feedback arrangement is disclosed for creating an opposing magnetic flux such that essentially zero magnetic flux is present in the magnetic cores of the windings.

Abstract: A magnetic sensor for measuring the helix current of a traveling wave tube (TWT). The sensor includes a helix current sense inductor and a reference inductor. The sense inductor includes windings for receiving the cathode and collector currents of the TWT and for receiving a bias current, and also a sense winding. The cathode and collector currents cause permeability of the core to vary in proportion to the difference between those currents, which is equal to the helix current. The bias current is supplied to the bias winding to compensate the sense inductor for temperature-related permeability variations. The bias current is supplied by the reference inductor which is selected to have magnetic properties which match those of the sense inductor. A plurality of sense inductors in conjunction with one common reference inductor may be used for sensing the respective helix currents in the TWTs in a multi-TWT array.

Abstract: The present invention is an arrangement for measuring electrical power. The arrangement comprises a conductor traversed by an electrical current i and a voltage-to-current converter for transforming an electrical voltage u.sub.N into a proportional supply current i.sub.N for a Hall element. The Hall element is adapted to produce an intelligence containing output signal .+-.u.sub.H proportional to the product (.+-.i.u.sub.N) of the current i and the voltage .+-.u.sub.N. The Hall element is arranged in an air-gap of a ferromagnetic core that is excited by the current i. A voltage-to-frequency converter transforms the Hall element output voltage .+-.u.sub.H into a proportional output frequency. The voltage-to-frequency converter includes a capacitor for integration purposes and at least two signal sources. The power measuring device also includes a switch for periodically switching a signal proportional to the signal .+-.u.sub.H and for switching said signal sources to compensate for an offset voltage.

Abstract: Drift compensation for the output signal of a magneto-optic current measuring system is achieved through the use of two light emitting sources, each at different frequencies, to generate two alternating optical input signals to the current sensor to establish a signal reference in order to compensate for signal drift caused by variable attenuator characteristics of the optical elements in the system.

Abstract: Two ferromagnetic cores (11, 12) are provided for a transformer, only one of the cores (11) exhibits an air gap (13) in which a Hall effect element (3) is housed. The current flowing in a conductor (10) can be direct or alternating current and induces in the core (11) a corresponding magnetic field which makes it possible to obtain a signal on the element (3). This signal is amplified by an amplifier (8). The output current from amplifier (8) is applied to a winding wound around both cores (11, 12). For direct current and low frequency current, the winding current is proportional to the current in conductor (10). When the frequency of the current flowing through conductor (10) exceeds a certain value (several kHz), the gain of the amplifier (8) diminishes. A linear relationship between the conductor current and the current in the winding is maintained, however, because the high frequency is transmitted to the winding by the core (12).

Abstract: Measuring a DC or a low frequency AC current by feeding the current to be measured through the primary winding of a transformer, whereby a first flux is generated in the transformer and generating a modulating voltage and also phase shifting the modulating voltage. The phase shifted modulated voltage is applied across the secondary winding of the transformer with an amplitude so as to saturate the core. The phase difference between the modulating voltage and the phase shifted modulating voltage is monitored while feeding a compensating current of increasing amplitude through the secondary winding until the phase difference is zero. The amplitude of the compensating current at zero phase difference is a representation of the current to be measured.

Abstract: A magnetic field sensor having two component layer transistors of opposite polarities are cross connected together and give a higher degree of sensitivity, by virtue of that feedback effect. The magnetic field sensor serves for measuring a magnetic field and is supplied by way of a costant current source from a d.c. voltage supply. In an alternative embodiment, it has a working point adjusting circuit, a change-over contact circuit, and a voltage regulator for nullifying the offset voltage.

Abstract: A D.C. current transformer (used for measuring D.C.) comprising a common primary winding and a pair of saturable magnetic cores on which respective secondary windings are wound and connected in opposite series in series to a source of alternating e.m.f., is provided with phase-sensitive device for determining the sense of the unknown D.C. in the primary winding. The phase sensitive device periodically senses and integrates the voltage (whose waveform is the -45.degree. to +45.degree. portion of a sine wave) across at least one of the secondary windings. The sense of the integrated waveform depends on whether said voltage is initially positive or negative, and is determined by the sense of the unknown D.C. in the primary winding. Preferably said voltage is sensed at each half cycle of said alternating e.m.f.

Abstract: The measurement of large DC and AC currents, are measured by a zero-flux current transformer. Two identically wound toroidal cores in which the magnetic flux induced by a primary current is neutralized by a counter-flux induced by a compensation current is passed through a compensation winding (14) common to both cores and having many turns. The compensation current is adjusted by means of an amplifier so that the mean flux in the cores is zero. The intensity of the compensation current is measured by the voltage drop across a measuring resistor.

Abstract: A compensated measurement transducer for measuring a first current generates a first magnetic field of a predetermined direction which flows in a first circuit including a first conductor; a second current substantially similar to the first current is generated in a second circuit and the first current is measured by obtaining the value of the second current. The second circuit includes a compensating current conductor, which generates a second magnetic field, compensating the first magnetic field, a Wheatstone bridge to which both magnetic fields are applied, and an amplifier connected to the output of the Wheatstone bridge, and coupled to the compensating current conductor. An auxiliary magnetic field is applied to the Wheatstone bridge, which is connected to a current- or voltage-source, and includes four ferromagnetic and magnetoresistive thin film.

Abstract: A magnetic-field-dependent inductive proximity switch having a coil arrangement with a ferromagnetic core, which is saturation-sensitive with respect to the magnetic field to be picked up, and having an electronic analyzing circuit for triggering a switching process at a certain core saturation, is to be constructed so that its power requirement is very low, for example, in the range of 0.1 to 5.0 milliampere, and that, by means of said switch, a magnetic field can be picked up through a non-ferromagnetic wall and can be used to trigger switching operations.

Abstract: A transducer free of any magnetic core for contactless measurement of a current includes an electrically conducting strip adapted to carry the current in a predetermined direction. The current thus generates a first primary magnetic field which has a direction at right angles to the predetermined direction near one side of the strip, and a second primary magnetic field near the other side of the strip, which has a direction opposite to the predetermined direction. A first magnetic field sensor near one side measures the first primary magnetic field and provides a first output signal, and a second magnetic field sensor near the other side of the strip measures the second primary magnetic field, and provides a second output signal. A circuit connected to the first and second magnetic field sensor processes the first and second output signals, and generates an output signal proportional to the measured current.

Abstract: Optical fibre interferometer for measuring a current carried by a high voltage line of the type comprising a winding traversed by a feedback current, having at least one base at earth potential, incorporating the interferometer core and the feedback winding, an insulating member and a measuring head mounted on a conductor traversed by the current to be measured. The insulating member is a rigid member forming a support or, in a preferred variant, a tubular insulating member having a flexible wall and provided with skirts made from an insulating material with a rounded "water droplet" profile.

Abstract: There is provided by this invention an electronic circuit for interfacing with a magneto-optical current sensor employing the Faraday effect to measure current in a high voltage transmission line. A DC biasing voltage is applied to the output of a photodetector to substantially eliminate the DC component providing a substantially AC output signal to the circuit. There is also provided a negative low pass error feedback to self-calibrate the circuit.

Abstract: In order to measure the intensity of an electric current utilizing the Faay effect, an optical path which is exposed to a magnetic field generated by the current is marked by an optical fiber which is laid in a number of windings in the shape of a coil. In order to minimize the disruptive effect of, for instance, elliptical eigen-birefringence of the fiber, or birefringence caused by the laying of the fiber on the zero point and the calibration factor of the device, the end of the optical fiber which is away from the input point is provided with a reflection unit which reflects back into the fiber the light which arrives there with the same polarization state with which it arrived at the reflection unit. A polarization measurement unit is used to record the polarization state of light flux which, after having traversed the optical fiber a total of twice, again emerges at the input point.

Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g., 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: A single-coil wound on a ferrite core surrounding a current path is driven from a voltage controlled constant current source. The coil drive current is modulated with a fixed frequency squarewave. The average voltage present across the coil is sensed and integrated to provide an output signal which is proportional to the current flow and also provides a negative feedback to the voltage controlled current source to bias the modulated drive current in a direction which compensates for the biasing effects of the current flowing in the conductive path.

Abstract: A current sensor, integratable with power switching and control circuitry on a common substrate and insulatable from current-carrying conductors, utilizes a piezoelectric element located between a pair of current-carrying conductors. The conductors carry a current flowing in the same direction, causing an attractive force therebetween to act upon the piezoelectric element and generate a voltage therein proportional to the square of the conductor currents. Use of a pair of sensors, each in a different portion of a half-bridge circuit, and associated electronics for providing a sensor output proportional to the instantaneous value of the sensed current, is also described.

Abstract: In an apparatus for the measurement of electrical power, including a multiplier which receives on an input thereof an electrical signal proportional to the voltage component of the electrical power, and which is subjected to an external magnetic field proportional to the current component of the electrical power, an auxiliary magnetic field is applied to the multiplier. The multiplier is a Wheatstone bridge including four ferromagnetic and magnetoresistive thin films, and the magnetic fields have a direction along the direction of the hard magnetic axes of each of the thin films. The thin films are so positioned that the magnetization of two electrically oppositely disposed thin films resulting from the application of the external magnetic field thereto is rotated in a direction opposite to that of the correspondingly resulting magnetization of the remaining thin films, following application of the auxiliary magnetic field to the films.

Abstract: A current to pulse-sequence transducer for transforming a current to be measured into a sequence of pulses which has a certain mark-to-space ratio, includes a first transforming device for transforming the current to be measured into a measurement magnetic field, a second transforming device for generating a reference magnetic field, and magnetic field comparison device including a magnetoresistive thin film comparator normally providing a zero output when the fields are equal, but generating an impulse when the strength of one magnetic field exceeds that of the other, and an impulse processing device. The impulse processing device includes a differentiator amplifier connected to the output of the magnetoresistive thin film comparator and a Schmitt trigger circuit postcoupled to the differentiator amplifier.

Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g., 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g., 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: A clamp-on ammeter for measuring current flows in a conductor is described. The ammeter is of a type comprising a magnetic core which can be located about a conductor and an indicator which responds to the magnetic flux consequently generated in the magnetic core to produce a signal indicative of the magnitude of the conductor current. Means are provided for restoring the magnetic core to a predetermined magnetic state for each measurement. The resetting means include a coil wound about the core and a coil energizing circuit which can be activated to produce in the core a residual magnetic flux substantially identical to that produced in the core when unmagnetized by a DC conductor current of predetermined magnitude, which represents the maximum value of any DC current which can be measured by the ammeter.

Abstract: The invention relates to a method and a system for analyzing the secondary current (J.sub.2) of a current transformer (20), the primary side of which is connected into a line (10) of an electric energy supply network. When the current transformer (20) is saturated as the result of a short-circuit on the line (10), a saturation signal (X) indicating this saturation and a polarity signal (P) indicating the polarity of the displacement of the short-circuit current (J.sub.1) are generated. The two signals (X, P) are used to select zero transitions of the secondary current (J.sub.2), corresponding to the polarity of the displacement of the short-circuit current (J.sub.1). After the selected zero-transitions, the secondary current (J.sub.2) is extrapolated by a current signal (C), in accordance with its saturation-free curve-shape. The current signal (C) is finally supplied to protective systems, instead of the secondary current (J.sub.2).

Abstract: A measuring transformer comprises a measuring conductor carrying the current I.sub.m to be measured, a pre-magnetizing winding which carries a pre-magnetizing current I.sub.v, and a magnetic field comparing means which is exposed to the magnetic field produced by the current I.sub.m and the magnetic field produced by the pre-magnetizing current I.sub.v and is alternately controlled in both directions of saturation. The magnetic field comparing means is a magnetic film which may be anisotropic, operated in the magnetic preferential direction, and have a thickness of at most a few microns. It may be secured to pole shoes of a magnetic core or arranged between a flat measuring conductor and a pre-magnetizing coil of flat cross-section. The measuring transformer can be used as an input transformer in a static electricity meter. In a further embodiment, the output pulses can be obtained directly from the magnetic field comparing means.

Abstract: An electric watthour meter for measuring AC power consumption is disclosed which includes a pair of parallel plate bus bars through which all of the power to be measured is conducted, a magnetoresistive bridge sensor disposed between the pair of bus bars such that the flow of current in either or both of said bus bars produces a corresponding voltage signal from the sensor indicative of the total amount of current flowing in the bus bars and a signal processing system for utilizing the signal from the sensor to produce an output indicative of the total AC power conducted by the bus bars.

Abstract: A current sensor, responsive to the first power of a current to be measured, utilizes a piezoelectric element located between a current-carrying conductor and a permanent magnet having its north-south poles aligned normal to the direction of current flow through the conductor. The substantially constant magnetic field provides a sensor output, taken from electrodes upon opposite surfaces of the piezoelectric member, which is proportional to the first power of current flowing in the single conductor.

Abstract: A current divider for use in connection with a measurement transducer. The measurement transducer includes a magnetic core, is formed as a substantially flat and longitudinal conductor with two longitudinal slits so as to partition the flat conductor into at least a measurement conductor, and at least two shunts are connected in parallel with the measurement conductor. The shunts define a plane, and the measurement conductor is disposed in the plane between the shunts. The flat conductor has two openings along the longitudinal direction, to receive the magnetic core. One slit communicates with one opening, and the other slit communicates with the other opening.

Abstract: A current measuring system includes three toroidal magnetic cores. The first core has a non-linear B-H characteristic and being adapted for operation in and between its saturation ranges of its B-H characteristic. The second and third cores are adapted for operation in their substantially non-saturating range of their B-H characteristics. The first core is coupled in a flux oscillator configuration to provide a first error signal representative of low frequency flux changes in the core. The first core and the second core each have noise cancellation windings which are shorted in a manner cancelling noise. A high frequency sensor winding on the third core provides a second error signal representative of intermediate and high frequency flux changes in that core. A feedback network combines the first and second error signals to generate a bucking current which is coupled by way of bucking windings on all three cores.

Abstract: In a magnetoresistive current detector, which includes a conductor carrying a current to be measured, which in turn generates an external magnetic field, four bridge elements are connected to one another so as to constitute a Wheatstone bridge. The Wheatstone bridge is adapted to be fed by a supply current from a current- or voltage-source and includes two pairs of ferromagnetic and magnetoresistive thin films which have hard and easy axes, respectively, and each thin film constitutes a respective bridge element. The thin films of each pair are magnetostatically coupled to one another, so that the portion of the supply current flowing in each thin film of each pair generates an auxiliary magnetic field, which has a direction along the hard magnetic axis of the other thin film of the same pair.

Abstract: A current detector comprising a current-pulse duty conversion element including a core of an amorphous, magnetically soft material having a first and a second coil disposed thereon. A current which is to be determined is passed through the first coil while the current flowing through the second coil is detected. A pulse of a given frequency is applied to one end of the second coil while the other end of the second coil is connected with an element which converts the current flowing through the second coil into a corresponding voltage. A voltage developed across the element is integrated and then converted into an analog voltage. The duty ratio of the voltage pulse appearing across the element which is connected to the other end of the second coil changes in accordance with the value of current passing through the first coil, whereby the analog voltage shifts.

Abstract: A polarity sensitive relay fabricated of and controlled by, solid state components is provided to produce a more trouble-free and smaller device. The relay may be made in first and second versions, the first of which responds to input signals of a single polarity and the second of which produces first and second output signals in response to input signals of first and second polarities, respectively. The relays include first or second Wiegand modules each of which has a drive coil, an input signal coil and an output signal winding. The Wiegand modules are placed in a steady state magnetic bias and the drive coils pulsed at a predetermined frequency. When two modules are used, the input signal coils are connected in series and in a manner to produce opposite magnetic effects on their associated Wiegand modules.

Abstract: A current-measurement transducer comprises a thin-film magnetic coil for passing an alternating premagnetizing current, generating an alternating premagnetizing field, and a magnetic-field comparator which includes first and second magnetic anisotropic films disposed in respective substantially parallel planes. Each film is composed of ferromagnetic and magnetoresistive material, and defines a magnetic easy axis, along which the film is relatively easily magnetizable, and a magnetic hard axis, at right angles to the easy axis, along which the film is harder to magnetize than along the easy magnetic axis. A non-magnetic and electrically at least poorly conducting layer separates the films, and the films are coupled to one another sufficiently tightly so that a current passing in one magnetic film generates an auxiliary magnetic field along the hard magnetic axis of the other magnetic film.

Abstract: A pair of semi-circular, hard magnetic sensors are rigidly fixed within separate blocks which are in turn removably received in corresponding housings mounted to the jaws of a spring biased clamp. The clamp is adapted for positioning the sensors into a split ring around a wire carrying the DC current to be measured. According to a first embodiment of the method, longitudinally wound coils about each of the sensors are momentarily energized by an AC current source connected thereto through a variable transformer, while the sensors are around the wire. Thereafter the sensors are removed from the clamp and placed side by side beneath a compass so that the magnetic flux previously induced in the sensors deflects the compass needle from North. Circumferentially wound coils about each of the sensors are connected to a DC current source which is varied to move the compass needle back to North by cancelling the magnetic flux previously induced in the sensors.

Abstract: A dc ground fault detector in which ground fault is sensed by noting an imbalance of magnetic flux due to a pair of windings on a toroidal core.

Abstract: The current-measuring device in accordance with the invention comprises an optical fiber wound around the conductor in which flows the current to be measured, a laser source, means for separating the radiation emitted by the source towards the two ends of the wound fiber, and for recombining the radiation emerging from these two ends, a conductor circuit through which flows an adjustable reference current, a detection device supplying a signal characteristic of the interferences between the two waves emerging from the fiber, the reference current being adjusted so that the phase shift between the two contra-rotating waves in the fiber is zero, this current being then proportional to the current to be measured flowing in the principal conductor.

Abstract: A transducer for measuring a current, includes a magnetic core which has a gap substantially impeding passage of any magnetic flux, a coil arranged to pass a premagnetizing current for producing a first magnetic field, a loop for carrying the current to be measured, so as to produce a second magnetic field, and a magnetic field comparision device exposed to the magnetic fields. The magnetic field comparison device includes a magnetic film bridging the flux gap. The film is alternately controllable in respective opposite directions of saturation substantially by the first magnetic field, and evaluates the measuring current in dependence of the magnetic fields. The magnetic core, the coil, the loop, and the magnetic film are substantially disposed concentrically.

Abstract: A multi-mode optical fiber is used to detect electrical currents or magnetic fields from a remote source. The optical fiber, which serves as the sensor, is composited with metal capable of conducting electricity. Optical radiation is introduced into the fiber from a source which may be either coherent or incoherent. An electrical current is applied to the portion of the electrically conducting optical fiber and a magnetic field is applied to the current-carrying optical fiber. A known value of one permits a determination of the presence or absence of the other through electromotive forces on a metallic conductor in a magnetic field, which are used to induce differential phase shifts (coherent optical radiation input) or losses (incoherent optical radiation input) between the fiber modes. These phase shifts or losses are detected by a suitable detector. For a magnetic field of 1 kGauss, good linearity is obtained in the 5 to 2,000 mA current range. Magnetic fields of about 0.

Abstract: A control system and method for an apparatus to glow discharge treat (such as ion nitride) a workpiece. The apparatus includes a housing to receive a workpiece and a low pressure atmosphere of ionizable gas (nitrogen and hydrogen for nitriding), and connectors for establishing a glow discharge in the gas with the workpiece connected as the cathode. The control system and method automatically control the apparatus throughout the process, utilizing operator selected parameters (such as warm-up time, processing time, workpiece operating temperature and chamber pressure). The control system divides the selected operating temperature by the selected warm-up time to provide a straight line increase per unit time of the workpiece temperature. Initially the control system accumulates the increases at a rate higher than the straight line increase and then, as the workpiece approaches the selected operating temperature, the control system accumulates the increases at a rate less than the straight line increase.

Abstract: A method and apparatus for measuring magnetic fields and electric current flow in biological systems and other systems employing a room temperature pick-up probe connected to a superconducting quantum interference device (SQUID).

Abstract: For use in D-C power transmission systems there is provided a circuit breaker system which is responsive to leakage currents to ground to break the circuit from the power source to the D-C transmission lines. A toroidal saturable core surrounds the D-C transmission line feed conductors and carries on such core a primary and a secondary transformer winding. An A-C source is connected to the primary winding in series with one of two field coils in the electromagnetic circuit of an electromagnetically actuated circuit breaker. The other field coil in the electromagnetic circuit of the breaker is connected to the secondary winding on the saturable core.

Abstract: A method of, and apparatus for, the detection of magnetization of a magnetic circuit, especially for the detection of a current flow interlinked with the magnetic circuit, wherein a timed or temporal cyclic magnetic flux change is generated by means of a detection-current flow used for detection purposes and interlinked with the magnetic circuit and a detection signal is formed as a function of time intervals dependent upon the magnetization.

Abstract: A measuring transformer comprises a measuring conductor carrying the current I.sub.m to be measured, a pre-magnetizing winding which carries a pre-magnetizing current I.sub.v, and a magnetic field comparing means which is exposed to the magnetic field produced by the current I.sub.m and the magnetic field produced by the pre-magnetizing current I.sub.v and is alternately controlled in both directions of saturation. The magnetic field comparing means is a magnetic film which may be anisotropic, operated in the magnetic preferential direction, and have a thickness of at most a few microns. It may be secured to pole shoes of a magnetic core or arranged between a flat measuring conductor and a pre-magnetizing coil of flat cross-section. The measuring transformer can be used as an input transformer in a static electricity meter. In a further embodiment, the output pulses can be obtained directly from the magnetic field comparing means.

Abstract: A method and apparatus for monitoring conductor currents for a fault current which changes the magnetic bias of a magnetic circuit in which the magnetization of the magnetic core is alternatingly reversed by sequences of magnetizing pulses and a determination made of the number of pulses up to which the pulse amplitude exceeds predetermined voltage reference value, with the change of this number of pulses used to derive an output signal.

Abstract: An electrical measuring apparatus comprising a current domain magnetometer (C.D.M.) (1) and summation means (2) for summing the output pulses from the C.D.M., the sum of the summation means representing the integral of a predetermined function of the voltage and magnetic flux applied to the C.D.M. with respect to time. The predetermined function may be proportional to the product of the voltage and magnetic flux and the apparatus may produce measurements of voltage, magnetic flux, power or phase angle.

Abstract: A transformer device comprises a saturable magnetic core having control and controlled windings, the saturable magnetic core being controlled in a feedback mode through switch means such as transistor switch means. The transformer device may comprise two magnetic cores and changes in magnetic resistance between the two magnetic cores are differentially fed back and amplified to cause an oscillative switch means to be turned on and off. A current to be detected flows in the control winding and detected by the controlled winding. The detected output corresponds to the polarity and the absolute value of the current supplied to the control winding. The transformer device not only can detect or measure the primary current but can identify the polarity thereof, differing from prior art dc current or potential transformers. The transformer device of the invention operates substantially free of slot-ripple inherent in the prior art transformer.

Abstract: A probe for sensing energizations of electrical components and particularly the energization of a relay or solenoid, the probe utilizing a magnetic switch as a sensor, a light-emitting diode as an indicator and a battery as a power source, the elements encapsulated as a unit in an epoxy material.

Abstract: Current measuring system particularly suitable for use as an earth leakage detection system and functional device equipped with such a system e.g. an earth leakage switch.

Abstract: A direct current detecting device is disclosed in which two pairs of saturable cores are provided so as to enclose a conductor carrying a direct current to be measured. On each of the saturable cores, a bias winding, a feedback winding and an output winding are wound. First and second output circuits are provided, each connected with a pair of output windings and each including two closed current paths consisting of the output winding, a common load, a common A.C. supply source and a diode. The diodes function to allow the greater one of current flows of the two closed paths to be passed through the common load. An amplifier is connected to receive the difference between output signals of the two output circuits. The output of the amplifier is supplied to the feedback winding whereby the magnitude of the feedback current becomes a function of the magnitude of the current flowing through the conductor.

Abstract: A measuring transformer comprises a measuring conductor carrying the current I.sub.m to be measured, a pre-magnetizing winding which carries a pre-magnetizing current I.sub.v, and a magnetic field comparing means which is exposed to the magnetic field produced by the current I.sub.m and the magnetic field produced by the pre-magnetizing current I.sub.v and is alternately controlled in both directions of saturation. The magnetic field comparing means is a magnetic film which may be anisotropic, operated in the magnetic preferential direction, and have a thickness of at most a few microns. It may be secured to pole shoes of a magnetic core or arranged between a flat measuring conductor and a pre-magnetizing coil of flat cross-section. The measuring transformer can be used as an input transformer in a static electricity meter. In a further embodiment, the output pulses can be obtained directly from the magnetic field comparing means.