Study of an accurate dc busbar current measurement technique by using a transductor based network
TL;DR: In this article, the output signal has been used to send a feedback current through a feedback winding in order to nullify the magnetisation component of the dc flux and thus the measurement may be assumed to be more accurate with respect to other similar instruments.
Abstract: The conventional single core or two core saturable reactor or transductor used for dc busbar current measurement may suffer from errors due to the magnetisation component of the dc flux and the asymmetry of the core materials. In the present paper a feedback technique of this type of dc current measurement has been developed. In this technique, the output signal has been used to send a feedback current through a feedback winding in order to nullify the magnetisation component of the dc flux and thus the measurement may be assumed to be more accurate with respect to other similar instruments. The developed network has been studied up to a dc busbar current of 50 A and the output characteristic has been found to be quite linear. The design of the network, its principle of operation and experimental data are reported in the present paper.
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TL;DR: In this paper, a brief overview of traditional methods of measurement of electric current and some relatively new types of current sensors are discussed, including Hall sensors with field concentrators, AMR current sensors, magneto-optical and superconducting current sensors.
Abstract: The review makes a brief overview of traditional methods of measurement of electric current and shows in more detail relatively new types of current sensors. These include Hall sensors with field concentrators, AMR current sensors, magneto-optical and superconducting current sensors. The influence of the magnetic core properties on the error of the current transformer shows why nanocrystalline materials are so advantageous for this application. Built-in CMOS current sensors are important tools for monitoring the health of integrated circuits. Of special industrial value are current clamps which can be installed without breaking the measured conductor. Parameters of current sensors are also discussed, including geometrical selectivity. This parameter specific for current sensors means the ability to suppress the influence of currents external to the sensor (including the position of the return conductor) and also suppress the influence on the position of the measured conductor with respect to the current.
210 citations
TL;DR: The advances in the field of magnetic sensors: both, sensors of magnetic field and sensors that use magnetic materials or principles for measuring non-magnetic quantities are discussed in this article.
Abstract: In this chapter, we cover the advances in the field of magnetic sensors: both, sensors of magnetic field and sensors that use magnetic materials or principles for measuring nonmagnetic quantities. The overview of materials used for magnetic sensors comprises semiconductor materials and the soft and hard magnetic materials in thin film, bulk, and tape form in detail. We discuss the properties and effects most critical for the decisive parameters of magnetic sensors, for example, remanence, crossfield sensitivity, and temperature stability of the offset. By far, most of the produced magnetic sensors are devices based on the Hall effect. These semiconductor sensors are cheap and can be made small, but their resolution and stability is rather limited. The fast development of ferromagnetic magnetoresistors (AMR, GMR, and SDT) for magnetic reading heads also brought these devices into the sensor scope. In the chapter devoted to fluxgate sensors, we concentrate on miniaturization of these traditional devices and compare them to GMI sensors. We describe the status of resonant sensors, induction coils, and SQUIDs, and briefly mention other more exotic methods of magnetic field measurements. An overview of magnetic sensors for mechanical quantities, such as position and force, is also given with special focus on torque sensors. One section is devoted to the sensing of electric current based on magnetic principles. In conclusion various applications of magnetic sensors are listed and discussed.
23 citations
TL;DR: In this article, the authors describe the development and implementation of a modified ammeter to facilitate fraud detection in lowvoltage consumer units, which has three modules: a meter affixed to the top of a stick, which is the local unit and it measures the consumer current; another instrument that transmits the measured current after the customer's meter via radio frequency, and it is the remote unit; and the third is a receiver unit that displays the measurements made by the local and remote units.
Abstract: This article describes the development and implementation of a modified ammeter to facilitate fraud detection in low-voltage consumer units. The device has three modules: the first is a meter affixed to the top of a stick, which is the local unit and it measures the consumer current; the second is another instrument that transmits the measured current after the customer’s meter via radio frequency, and it is the remote unit; and the third is a receiver unit that displays the measurements made by the local and remote units. On the receiver unit display, the operator can check and compare the two (local and remote) measures detecting fraud by determining if there is a difference between the measures. The paper illustrates field measurements performed in a test for a Brazilian electric utility.
21 citations
03 Feb 2014
TL;DR: In this paper, a brief overview of traditional methods of measuremet of electric current and relatively new types of current sensors are discussed, including Hall sensors with field concentrators, AMR current sensors, magnetooptical and superconducting current sensors.
Abstract: The paper makes a brief overview of traditional methods of measuremet of electric current and shows in more detail relatively new types of current sensors. These include Hall sensors with field concentrators, AMR current sensors, magnetooptical and superconducting current sensors. The influence of the magnetic core properties on the error of the current transformer shows why nanocrystalline materials are so advantageous for this application. Built-in CMOS current sensor are important tools for monitoring of the health of integrated circuits. Of special industrial value are current clamps which can be installed without breaking the measured conductor. Parameters of current sensors are also discussed, including geometrical selectivity. This parameter specific for current sensors means the ability to suppress the influence of currents external to the sensor (including the position of return conductor) and also suppress the influence on the position of the measured conductor with respect to the current.
1 citations
References
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01 Jan 1992
145 citations
TL;DR: This paper presents an algorithm that is able to calculate the intensity of a dc current flowing in a rectangular bus-bar, in the presence of crosstalk fields.
Abstract: A single solid-state magnetic sensor can measure a current flowing in a conductor in a noncontact way. In order to improve the accuracy of the measuring system and to reduce the crosstalk effects of other magnetic fields, circular arrays of magnetic sensors can be fabricated, still preserving low costs. In those kind of arrays, the sensing elements are assembled on a circle around the conductor. The sum of the sensor output signals is an approximation of Ampere's circulation. A quite satisfactory crosstalk effects reduction can be thus achieved. More sophisticated algorithms that combine sensor output signals are necessary in order to further reduce crosstalk effects. This paper presents an algorithm that is able to calculate the intensity of a dc current flowing in a rectangular bus-bar, in the presence of crosstalk fields.
106 citations
TL;DR: In this article, a new algorithm based on spatial Discrete Fourier Transform (DFT) capable of calculating the current to be measured is presented, which can be implemented by a DSP that processes output signals of solid state magnetic sensors forming a circular array centred in the current conductor.
Abstract: Solid state magnetic sensors can measure a current by sensing the field near the conductor. Means are required to distinguish between useful and interference fields and that are those of conductors near the current under measurement and environmental fields. Starting from analytical expressions of the magnetic field, spatial harmonic analysis is performed. It is then possible to separate the effects of the field generated by the current under measurement from those of interference fields. A new algorithm based on spatial Discrete Fourier Transform (DFT) capable of calculating the current to be measured is presented. The algorithm can be implemented by a DSP that processes output signals of solid state magnetic sensors forming a circular array centred in the current conductor.
69 citations
04 Jun 1996
TL;DR: In this paper, three novel DC current sensors are described, including portable 40 A DC current clamps with resolution of 1 mA and high immunity to unclamped currents and external fields.
Abstract: Three novel DC current sensors are described. Portable 40 A DC current clamps have resolution of 1 mA and high immunity to unclamped currents and external fields. AC/DC comparator with amorphous core may serve for precise measurement of DC currents with AC component up to 1 kHz. Magnetoresistive sensor field has limited accuracy but potential bandwidth from DC to 1 MHz.
38 citations