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Current transformer

About: Current transformer is a research topic. Over the lifetime, 24211 publications have been published within this topic receiving 134243 citations. The topic is also known as: CT & electric current transformer.


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Patent
18 May 1994
TL;DR: In this article, the phase-control angles of the A-D converter were adjusted to damp the vibrations of load positively even at the time of soft start and soft stop by connecting switching elements in antiparallel with each phase of a power supply path and controlling the phase control angles of each switching element.
Abstract: PURPOSE: To damp the vibrations of load positively even at the time of a soft start and a soft stop by connecting switching elements in antiparallel with each phase of a power supply path and controlling the phase-control angles of each switching element. CONSTITUTION: When a current transformer 11 detecting currents flowing through a motor 5 is mounted and ACs generated on the secondary side are rectified by a rectifier circuit 12, an A-D converter B converts ACs into a digital signal, and transmits the signal over a microcomputer 9. The microcomputer 9 reads the current value, and uses the current value for arithmetically operating the phase-control angles of semiconductor switches 2, 3, 4. A detecting means 9a detecting the vibrations of the motor 5 from the read current value is provided, and the state of the control of the phase-control angles is changed in response to the generation of vibrations. The line voltage in v phase and V phase of a three-phase AC power 1 is stepped down by a transformer 7, and input to a rectifier circuit 8. The microcomputer 9 detects the rise of the rectangular wave signal of AC power-supply voltage, and controls the firing time, the phase-control angles, of the semiconductor switches 2, 3, 4. COPYRIGHT: (C)1995,JPO

3 citations

Journal ArticleDOI
TL;DR: In this paper, the authors have shown that the observed width of the transition of indium in an applied magnetic field can be greatly reduced by maintaining zero current in the flux transformer.
Abstract: The changing magnetization of a sample in a superconducting flux transformer coupled magnetometer induces a current in the transformer which in turn changes the field at the sample. This ‘‘image’’ field and the error caused by it can be eliminated by sensing the current in the loop and nulling it by feedback through a mutual inductance. We have tested the technique on the superconducting transition of indium in an applied magnetic field and shown that the observed width of the transition is greatly reduced by maintaining zero current in the flux transformer.

3 citations

Patent
18 Jan 2006
TL;DR: In this paper, a method for controlling motor soft starting or soft stopping, comprising the following steps: entering starting or stopping course, outputting the work voltage to motor through silicon controlled; controlling angle of flow of silicon thyristor according to the predetermining motor voltage increasing or lowering curse; sampling voltage and current signal via current transformer.
Abstract: This invention discloses a method for controlling motor soft starting or soft stopping, comprising the following steps: entering starting or stopping course, outputting the work voltage to motor through silicon controlled; controlling angle of flow of silicon thyristor according to the predetermining motor voltage increasing or lowering curse; sampling voltage and current signal via current transformer; comparing the sampled signal and predetermining signal to test whether the present voltage current signal is balancing; adjusting the angle of flow of thyristor via feedback signal of three-phrase trigger; when the torsion of motor achieve nominal torsion( when starting), placing the work voltage in byline contactor, then output to motor, or when the voltage decreases to zero( when soft stopping), the course of soft stopping ends. The invention also provides a device used for above method to increase the safety of motor starting and stopping.

3 citations

Patent
30 Mar 2011
TL;DR: In this paper, a system for measuring the resistance of battery circuits, particularly banks of batteries arranged in parallel connections in automatic fire detection and protection devices, is described, where each measured circuit has the current transformer PP with a load in the form of the resistor Ro connected in series and the parallel resonant circuit RLC, and the measuring signals taken from these loads are routed through the amplifiers Kz, whereas the voltage measuring signal is additionally passed through the amplifier KUz, and the outputs of both of these amplifiers are fitted with the phase-sensitive detectors DET controlled
Abstract: A system for measuring the resistance of battery circuits, particularly banks of batteries arranged in parallel connections in automatic fire detection and protection devices is the object of the invention. In the system according to the invention each measured circuit has the current transformer PP with a load in the form of the resistor Ro connected in series and the parallel resonant circuit RLC , and the measuring signals taken from these loads are routed through the amplifiers Kz , whereas the voltage measuring signal is additionally passed through the amplifier KUz , and the outputs of both of these amplifiers are fitted with the phase-sensitive detectors DET controlled by the clock signal CLK, which is switched by a microprocessor system to step-change its phase by 90° between measurements.

3 citations

Journal Article
Viscas Wire1
TL;DR: In this paper, an optical current transformer is constructed by exposing gain mangetostrictive material (GMM)-FBG system to current-induced magnetic fieldFerro-magnetic materials are used to design a loop to constraint and conduct the flux into GMMThe permanent magnetic material is used in loop to establish a bias flux to form a working bias for the system.
Abstract: An optical current transformer is constructed by exposing gain mangetostrictive material(GMM)-FBG system to current-induced magnetic fieldFerro-magnetic materials are used to design a loop to constraint and conduct the flux into GMMThe permanent magnetic material is used in loop to establish a bias flux to form a working bias for the systemFinite element method is used to analyze and design the loop structure and the size Coarse wavelength division multiplexing(CWDM) device is used to demodulate the alternating strain on FBG caused wavelength drift to realize sensing of the currentIn the experiment,the maximum current is 186 A and the full scale accuracy is 43%when the system workes in linear region by setting the bias in 30 kA/mFast Fourier transform algorithm(FFT) is used to analyze the harmonic component of the output signal to evaluate the qualityIt is demonstrated that the output signal is not influenced by hysteresis and nonlinear effect of GMM in linear region

3 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202381
2022223
2021234
2020487
2019824
20181,054