238results about "Hysteresis curve measurements" patented technology

An apparatus for detecting a presence of an object is provided. The apparatus includes an inductive sensing coil that is configurable to generate a first magnetic field. The inductive sensing coil is configured to have an electrical characteristic that is detectable when generating the first magnetic field. The electrical characteristic is configured to vary as a function of a second time-varying magnetic field simultaneously applied to the object. The apparatus comprises a controller configured to detect a change in the electrical characteristic and determine a presence of the object based on the detected change in the electrical characteristic. The electrical characteristic comprises one or more of an equivalent resistance, an equivalent inductance, an equivalent impedance, and an impulse response of the inductive sensing coil. The object comprises one or more of a ferromagnetic object, a metallic film and a metallic foil.

The invention discloses an apparatus for measuring the ferroelectric hysteresis of ferroelectric materials which is based on a current measurement circuit, as well as a measurement method thereof. The invention inputs a simulated output signal generated by a computer processing unit into a high voltage amplifier through a signal source and a data acquisition board, thus giving excitation voltage to a sample being tested, and then through a sampling resistance R₀, sampled current signal is input into a signal regulating module through an operational amplifier, and then the sampled current signal is transmitted back into the computer processing unit through the data acquisition board. By separating the current signal acquired from the measurement into three parts as linear polarization, non-linear polarization and electric loss, the measurement system is provided with not only the function of measuring the P-E relationship, but also the function of acquiring the relationship between the real spontaneous polarization and induced polarization of the dielectric substance being tested and the field intensity. Furthermore, by superimposing actuating signal of a small alternative electric field to a bias electric field with constant intensity and synchronously collecting the corresponding change information of the polarization intensity of the sample being tested, then the reversible permittivity can be acquired.

The invention belongs to the optical technical field, in particular to a measuring device of magneto-optical kerr effect on longitudinal surface of a large field. The device consists of an electromagnet, a program control magnet power supply, a light path system and an operation control system (PC), wherein, the light path system subsequently consists of a semiconductor laser, a polarizing prism, a half transparent and half reflecting prism, a polarization detecting prism, a photodetector, a convex lens, a sample holder, an aperture, another polarization detecting prism, a long focal length convex lens and another photodetector; a magnetic filed for measurement is provided by the electromagnet which can provide a magnetic filed up to 1.5 tesla when the magnetic pole spacing is 4cm. The invention uses a converging convex lens to effectively expand the incident angle and the reflection angle of the light on the surface of the a sample, overcome the restriction of the magnetic pole spacing to the incident angle of the laser and enhance the magneto-optical kerr signal intensity on the longitudinal surface. The invention makes measurement of the high-coercivity magnetic film by the magneto-optical kerr effect possible.

An eddy current type sensor for detecting a conductor includes a LC circuit and an oscillator. The LC circuit has a coil and a capacitor connected in parallel with the coil. The oscillator supplies an alternating current of a predetermined oscillation frequency to the LC circuit. A signal voltage outputted from the LC circuit has a first voltage when the distance between the coil and the conductor is minimum and a second voltage when the distance between the coil and the conductor is maximum. A voltage difference between the first and second voltages has a first difference at a first temperature and has a second difference at a second temperature. The first and second differences become equal to each other at a first frequency and a second frequency. The oscillation frequency is set close to the first frequency or the second frequency.

The invention relates to a method for estimating the residual magnetism of a transformer core based on the slope of a local hysteresis loop, which comprises the following steps: S1, measuring the saturation hysteresis loop of a transformer core material; S2, using a JA model to simulate the hysteresis characteristic of the transformer coil; S3, getting the relation between the residual magnetism and the slope of a local hysteresis loop near a residual magnetism point based on the JA model, and fitting the relation to get a corresponding formula relation; and S4, powering on and testing a transformer coil under test, getting the positive and negative slope near the residual magnetism point through electromagnetic relation conversion, and calculating the residual magnetism value according tothe formula obtained in the previous step. The method of the invention is simple. There is only the need to apply small positive and negative excitation and record the voltage and current in the residual magnetism calculation experiment. No complicated online experiment is needed. The test power is low, and the experimental cost is low.

An arc fault circuit interrupter includes separable contacts, an operating mechanism, a current sensor sensing current flowing through the contacts and outputting a sensed current, and a processor determining and storing peak values of the sensed current for plural half-cycles. The processor provides arc fault detection, determines whether a first predetermined plurality of half-cycles occur in succession and correspond to non-unity power factor, and responsively inhibits the detection for a first predetermined time, and whether a second predetermined plurality of half-cycles occur in succession, each with smaller peak amplitude than that of an immediately preceding half-cycle of like or differing polarity, and responsively inhibits the detection for a second predetermined time. The processor determines that the detection is not inhibited for the first and second predetermined times, and responsively indicates that any of the half-cycles having a peak amplitude greater than a predetermined amount is a parallel arc.

A non-contact printed circuit board (PCB) electromagnetic testing system comprises at least one high resolution transducer operative to induce multi-frequency, multi-amplitude eddy currents in a tested PCB, each such transducer including both a high frequency excitation coil that serves also as a sensing coil and a direct current (DC) bias coil operative to provide an optimal transducer operating regime; a multi-frequency generator for providing AC and DC bias signals to each transducer; and a control mechanism for driving the transducer. Optionally, the system further comprises an external ferrite concentrator that enhances a magnetic field flux focus and depth of focus on the inspected PCB. The mutli-frequesncy, multi-amplitude methods enable three-dimensional mapping of various features in the PCB with both high sensitivity and high resolution in respective operating regimes.

An on line test method and test system of differential type temperature-compensating bridge rope force based on the magnetoelasticity is disclosed. The bridge rope is the ferromagnetic material and placed in the specific magnetic field, the bridge rope will be magnetized; the magnetic conductivity of bridge rope will change with the variety of stress condition and temperature. The sensor comprises operating magnetic circuit and reference magnetic circuit, in every designing of the magnetic circuit, the bridge rope is just a part of the magnetic circuit and not as the iron core of the actuating coil and the measuring coil. The reference magnetic circuit of sensor just feels the changes of temperature, but the operating magnetic circuit feels the changes of temperature and rope force, the output signal of the operating magnetic circuit and the reference magnetic circuit is differential to eliminate the temperature effect, the value of rope force can be tested with the corresponding relationship between the change of magnetic conductivity and rope force. The test method of rope force in the invention characterized in high accuracy, well dynamic response, low price of sensor, convenience of mounting and conditioning, long service life, strong overcurrent protection power, fitting for static and dynamic measurement, sampling just in time in all-weather, the testing results are free of effects of anticorrosive coating and protective plastic casing which is in surface of bridge.

A measuring device consists of closed-loop soft magnetic material and magnetization coil and detecing coil wound on it; magnetization loop connected in series by magnetization coil, sampling resistance, variable resistance and adjustable DC power supply controlled with communication switch or relay as well as measuring loop formed by detecting coil and electronic integrator. The two ends of sampling resistance and output end of electronic integrator are connected to signal handling module and analog-digital conversion circuit as the converter digital signal is connected to computer through computer parallel interface or interface card.

The invention discloses a measuring device for a hysteresis loop made of a ferromagnetic material and an application method of the measuring device. The measuring device for the hysteresis loop made of the ferromagnetic material comprises an excitation circuit, a control circuit, an integrating circuit, a sampling resistor circuit, a liquid crystal display circuit, a key detecting circuit and an oscilloscope. According to the method, step values of excitation voltage and excitation resistance are set through programming a singlechip; the oscilloscope displays the hysteresis loop to be measured; and an upper computer measures and analyzes the coercivity, the remanence induction strength, the maximum field, the maximum magnetic induction strength and the magnetic hysteresis loss of the ferromagnetic material according to the hysteresis loop. The original mechanical switch and manual knob type switch control mode is replaced by a program control mode, and shortcomings that contacts of a knob switch are in a poor contact state easily, gears are easy to loosen, and the like are overcome. By an experimental instrument developed in the invention, the reliability of experimental equipment can be increased, and the service life of the experimental equipment can be prolonged. Owing to the program control mode, the step values of the excitation voltage are low, gears of the excitation voltage are sufficient, measurement precision is high, and practicality and accuracy are good.

Methods are described for the use of conformable eddy-current sensors and sensor arrays for characterizing residual stresses and applied loads in materials. In addition, for magnetizable materials such as steels, these methods can be used to determine carbide content and to inspect for grinding burn damage. The sensor arrays can be mounted inside or scanned across the inner surface of test articles and hollow fasteners to monitor stress distributions. A technique for placing eddy-current coils around magnetizable fasteners for load distribution monitoring is also disclosed.

The invention discloses a method for detecting material magnetic properties and stress based on a Barkhausen noise principle, wherein the method includes the steps: (1) through an envelope line of a Barkhausen noise signal, reckoning a ferromagnetic material magnetic hysteresis loop: (2) extracting stress detection characteristic values on the ferromagnetic material magnetic hysteresis loop: envelope area, center height difference, center width and integral curve area; (3) carrying out magnetic property and stress analysis of a ferromagnetic material by using the stress detection characteristic values, to obtain detection values of the material magnetic properties and stress; and (4) evaluating the stress detection characteristic values, and verifying the accuracy of the material magnetic property and stress detection values obtained by the magnetic property and stress analysis. The Barkhausen noise signal and the magnetic hysteresis loop are correlated in detection, the magnetic properties of the material are directly reflected and determined by the new characteristic values and the stress is detected by the new characteristic values, and the accuracy of stress detection is further improved.

The invention discloses a bubbling experiment device for the mechanical-electric-magnetic coupling behavior of an electromagnetic intelligent material and a test method. In the invention, the tested film material is subjected to elastic deformation, plastic deformation, interface cracking and even self fracture by a bubbling method under the effect of full coupling of the mechanical-electric-magnetic fields, and the device realizes real-time testing on the mechanical, electric and magnetic response of the tested material in the process, thereby being favorable for obtaining the information of the functional film material in multiple aspects and for understanding the internal mechanism more clearly and thoroughly; in the existing oil-pressure bubbling loading device, a closed-loop control mode is adopted to control the oil pressure loading for the first time, and multiple oil pressure loading modes are realized so as to widen the representation functions of the bubbling test device; by adopting the projection speckle and digital image related technology, the non-contact three-dimensional deformation test is realized on the film sample, and the displacement measurement accuracy is improved to 20nm; and the device and method are favorable for researching the mechanical, electric and magnetic comprehensive performance of the novel functional film material.

A method for determining tube support plate blockage of a steam generator includes the following steps: measuring at least five different eddy current values per tube support intersection; calculating a nominal clean fit radius of flow hole; determining a center signal response; converting the center signal response to a deposit thickness; determine an edge reduction; converting the edge reduction to an edge thickness; calculating the resulting flow hole radius; verifying the reasonableness of the resulting flow hole radius; and determining a virtual calibration range.

The utility model discloses a method utilizing a stray magnetic field signal monitoring the damage of ferromagnetic, which belongs to the magnetic nondestructive inspection field. Ferromagnetic components do not have measurable strain in early stages of service, with difficulty to evaluate damage. The utility model, inspected material and smooth plantlike standard fatigue specimens have the same heat treatment state, and are demagnetized through high temperature, so as to get the pure initial magnetic state. And then a constant rate is imposed to pull the tension fatigue load, every stray magnetic field normal component of the surface inspecting components is unloaded corresponding to scheduled cycles, the slope Ks of different magnetic cycle curves is extracted, the critical value of the slope Ksc is determined, and the mapping relationship between the slope Ks before fatigue crack and fatigue cycles N is established. The measured components by the same value are inspected, and the measured slope Ks of the magnetic curve is compared with the critical value of the slope Ksc, and then the fatigue damage can be determined. The utility model has the advantages that the utility model has simple operation and accurate inspecting results, and dynamic monitoring the early fatigue damage of the ferromagnetic components in the unloaded state can be achieved.

A method for determining a power flow in a distribution network includes the step of determining an admittance matrix for a circuit that includes a floating transformer in an electrical power distribution system. The admittance matrix includes an admittance of a fictitious shunt connected between a non-grounded winding of the floating transformer and ground. The method also includes the step of obtaining real time power measurements from a portion of the electrical power distribution system including the floating load transformer. The method further includes solving the power flow using the admittance matrix and the real time power measurements.

The invention relates to a device and a method for detecting a force thermal magnetic coupling action of a ferromagnetic thin film, and belongs to the technical fields of engineering materials, structure deformation and mechanical experiments. The device comprises a ferromagnetic thin film uneven stress measuring optical circuit, a film magnetic hystersis loop measuring optical circuit, a Helmholtz coil and a power supply thereof, a test piece heating table, a thermocoupler, a force loading structure and an adjusting bracket. The film uneven stress measuring optical circuit comprises a laser, a beam expander, a spectroscope, a reflector, a raster, a lens, a filtering screen and a CCD camera; and the film magnetic hystersis loop measuring optical circuit comprises a laser, a beam expander, a reflector, a polarizer, a polarization analyzer and a photodetector. The method utilizes the Helmholtz coil to provide an even magnetic field for the ferromagnetic thin film, utilizes the test piece heating table to heat the film, utilizes the force loading structure to carry out force loading on the film, utilizes shearing interference to measure uneven curvature of the surface of the film and further obtain the stress of the film through the curvature, and utilizes Kerr magnetooptical effect on the surface of the ferromagnetic thin film to measure a magnetic hystersis loop of the film.

An eddy current measuring probe sensor has an exciting portion and a detecting portion. The exciting portion includes a primary exciting portion that includes a main core formed of a cylindrical magnetic body and a main coil that is a solenoid coil wound in a circumferential direction around the main core, and a plurality of secondary exciting portions that include sub-cores formed of cylindrical magnetic bodies that are arranged around the primary exciting portion in a manner such that an axial direction of each of the sub-cores is the same as an axial direction of the main core. The plurality of secondary exciting portions are configured to be able to change the position of each sub-core independently in the axial direction relative to the primary exciting portion

A spatially resolved magneto-optic Kerr effect measurement device comprises an optical path system, a three-dimensional piezoelectric sample stage, and a current source control unit. The system can carry out poloidal or longitudinal Kerr signal scanning measurement of a single point quickly under a changing magnetic field, and can carry out Kerr signal measurement of the points in a region in a mode of matrix scanning under a fixed magnetic field. With the spatially resolved magneto-optic Kerr effect measurement device, the static magnetic domain and dynamic magnetic domain of a region can be measured precisely. Moreover, the magnetic domain structure of a whole region to be measured can be observed under a fixed magnetic field.

A common source double-frequency excitation type multifunctional micro-magnetic signal synchronous detection method is disclosed and belongs to the technical field of micro-magnetic nondestructive testing. Via use of the common source double-frequency excitation type multifunctional micro-magnetic signal synchronous detection method, five types of typical micro-magnetic detection parameters can be obtained synchronously, and detecting efficiency can be greatly improved. A standard micro-magnetic probe comprises an excitation magnetic circuit consisting of a magnetic core and an excitation wire coil, an induction wire coil wounded around the magnetic core, a Hall element used for detecting surface tangential magnetic field change of a ferromagnetic component being detected, and a Barkhausen noise detection wire coil. Sine wave superposed signals having a low frequency less than 100 Hz and a high frequency greater than 1k Hz that matche with an amplitude ration are used as excitation signals, and the excitation signals are sent into the excitation wire coil of the standard micro-magnetic probe so as to magnetize the ferromagnetic component being detected. The induction wire coil, the Hall element and the Barkhausen noise detection wire coil are respectively used for synchronously picking characteristic signals such as magnetic induction intensity time-varying signals, tangential magnetic field detection signals and Barkhausen noise detection signals; magnetic hysteresis loops, tangential magnetic field intensity time-varying signals, Barkhausen noise, eddy current impedance and incremental magnetic permeability can be quickly detected.

An automated tool for performing an EL CID inspection of the step iron region of a generator stator that can be employed with the rotor in place. The tool has a track that is axially cantilevered at one end and supported magnetically within a stator slot adjacent the region to be monitored. The track has a smoothly rounded contour that approximately conforms to the profile of the stator step region. A carriage carrying a pickup coil is slideably mounted on the track and is driven back and forth along the track over the area to be inspected by a remotely-operated drive system. A video camera is mounted on the track and provides a remote visual indication of the location of the carriage relative to the stator.