Contactless Transducer Research Articles

Static characteristics of contactless converters of monitoring and control systems

The paper substantiates the need to use non-contact conversion and measurement of large direct currents using magnetic modulation contactless transducers of increased sensitivity for land reclamation, irrigation, industry, metallurgy and agriculture and water management in general, and the results of their design development are presented. It is shown that the developed converter, in contrast to the known ones, has increased accuracy and sensitivity, a technologically advanced design and low weight and dimensions with low material consumption and cost. Characteristics of information non-contact magnetic modulation converters statically are considered. It is shown that the value of the excitation value corresponds to a certain maximum value of the measured value. In this case, the maxima of the measured value, increasing in value with an increase in the excitation value, are shifted towards the increase in the measured value. The discrepancy between the experimentally and theoretically obtained static characteristics of the converter does not exceed 6 percent. The developed converter can be widely used in electrical systems in land reclamation and irrigation, in water supply, industry, railway transport, science, technology, and for checking electric meters at their installation site for contactless control of direct and alternating currents.

Estimation of the error of a magnetic modulation non-contact wide-range device for non-destructive control of high amperage currents

The paper provides information on use of direct current (DC) energy in the electric power supply industry of agriculture and water management, hydraulic engineering construction, metallurgy, irrigation and melioration. The need for non-contact non-destructive control of high amperage DCs of high-capacity electrical installations in irrigation and melioration, hydraulic engineering has been identified. The basic requirements for non-contact transducers and sensors of high amperage DC measurements without circuit breaking are formulated. Identified priority directions in the development of above mentioned transducers. The general construction principles of non-contact ferromagnetic transducers of high amperage DCs and the results of the development of one of the modification of the developed wide-range magneto modulation contactless transducers of high amperage DCs and a device based on it are given. It is shown that the developed transducer and device, as distinct from the known ones, have increased accuracy and sensitivity, technological design and small weight and dimensions with low material consumption and cost. The error estimation of the developed magneto modulation non-contact wide-range device for non-destructive control of high amperage currents is carried out and it’s RMS (root-mean-square) and entropy errors are estimated. It can be widely used in power systems in irrigation and melioration, in water supply system, industry, railway transport, science, technology and for testing power meters at their installation site for contactless control of DC and also ACs (alternative currents).

ВІДБИТТЯ УЛЬТРАЗВУКОВИХ ХВИЛЬ ВІД ДВОШАРОВОГО ПАКЕТУ ТЕКСТИЛЬНИХ МАТЕРІАЛІВ ЗІ ЩІЛЬНИМ ВЕРХНІМ ШАРОМ

Obtain and show in general terms the expression for the module of the complex reflection coefficient of ultrasonic waves from a two-layer package of textile materials with a dense first layer. The above is necessary for the possibility of research of contactless control of such materials. To analyze the process of reflection of waves from a controlled material, the method of superposition of sounding vibrations is used. In general terms, the expression for the complex reflection coefficient of ultrasonic waves from a two-layer package of textile materials with a dense first layer is shown. It is proved that taking into account the complete attenuation of the reflected waves in the layer of the first material, it is possible to simplify the basic expressions for the complex reflection coefficient from a package of textile materials. It is shown that the change in the amplitude of the reflected ultrasonic waves for the material presented in the work with a change in the thickness of its layers is very small. The change in the amplitude of the reflected waves for such materials mainly causes a dense first layer of package of textile materials. The dependences of the real and imaginary parts of the complex reflection coefficient of ultrasonic waves on a package of textile materials with a dense first layer are obtained, which will help analytically determine both the change in the amplitude of the waves and their phase shift caused by the interaction of these vibrations with the material. It is proposed to use the component expressions for the module of the complex reflection coefficient of ultrasonic waves, which will allow you to adjust the parameters of the contactless transducers for different two-layer package of textile materials with a dense surface layer. To ensure the possibility of determining a small change in the measured magnitude of the amplitude of the reflected ultrasonic waves from the two-layer package of textile materials with the first dense layer, you can use switching and modulation devices and transducers. This will eliminate the errors that may be associated with the non-identity of the measuring channels when determining a small change in the amplitude of the reflected ultrasonic waves.

Contactless galvano-magnetics transducers of monitoring and control systems in agricultural energy

The paper provides information on the state of the use of direct current energy in the electric power industry of agriculture and water resource, hydraulic engineering, industry and metallurgy, irrigation, and land reclamation. Identified the need for contactless non-destructive testing of large constant currents in high-power electrical installations in irrigation, land reclamation, and hydraulic engineering. The basic requirements for contactless transducers and meters of large direct currents in circuits without breaking them are shown. Identified priority areas in the development of these transducers. The general principles of constructing contactless ferromagnetic transducers of large direct currents also the basic requirements for them and the results of the development of one of the options for the development of effective innovative galvano-magnetic contactless transducers of large direct currents with an expanded range of monitoring and control systems for powerful pumping stations in water supply and land reclamation are presented. To increase the sensitivity of galvanomagnetic contactless transducers of large direct currents, Hall transducers have supplied with short-term rectangular current pulses from a special generator. When measuring the amplitude values of the rectified current, in this case of galvanomagnetic contactless transducers, the supply of pulses of the control current of the Hall transducers with the converted current in the bus synchronization is provided. This is achieved by supplying galvano-magnetic contactless transducers of large direct currents with a magnetically controlled contact located near the bus with the converted current and included in the circuit of the current electrodes of the Hall transducers.A static characteristic of the developed galvano-magnetic contactless transducer of high currents obtained and its main technical characteristics and parameters are given. It is shown that the developed transducer, unlike the known ones, has increased accuracy and sensitivity, a technological design, and low weight and dimensions at low material consumption and cost. It can be widely used in electrical systems in land reclamation and irrigation, in water supply, industry, rail transport, science, technology, and for checking electric meters at the installation site.

Lumped parameter model and experimental tests on a pressure limiter for variable displacement pumps

The paper presents the lumped parameter model of a pressure limiter for axial piston pumps developed in the Simcenter Amesim®environment. The control includes both the absolute and differential (load sensing) pressure limiter in a single body. The continuous position valve was tested experimentally alone on a test rig in order to estimate the discharge coefficients required for tuning the model. The tests were performed at imposed positions of the spool and the corresponding modulated pressure and control flow through the valve were measured. A contactless transducer was used for measuring with a very high accuracy the spool position. The influence of the bleed orifice on the pressure gain was also measured experimentally. It was found that the discharge coefficients have a significant influence on the hydraulic characteristic of the valve with also a consequence on the dynamic behavior of the entire displacement control.

Six degrees of freedom measurement with continuous scanning laser doppler vibrometer

The dynamic response of a structure can consist of up to six degrees of freedom (DOF). Not all of them may be present at all times in a structure, but for a detailed finite element model validation it is important to provide as much information as possible. Current contact transducers can pick up a combination of some of the mentioned DOFs, but are not able to provide all six DOFs from a single transducer. Several contact-less transducers, such as a Scanning Laser Doppler Vibrometer (SLDV), can be combined to a single measurement system that allows the determination of up to three translational degrees of freedom at a point, but they are still not providing rotational information as the laser beam is fixed to a point. Continuously Scanning Laser Doppler Vibrometer (CSLDV) methods can partly overcome this issue by travelling in small circles around the measurement location and thus also sensing the rotation around the three axes at a point. An introduction of CSLDV methods for measuring DOFs at a point is given, focussing on a method for capturing up to 5 DOFs using a lens. However, the lens can make the measurement of the in-plane rotation very difficult and impractical. This paper presents a new type of scanning device which allows measuring all six degrees of freedom at a measurement location with a single setup and a single point LDV, by combining variable small circle scans. Experimental validation of the scanning head is presented and the measurement of the last DOF, the in-plane rotation, is demonstrated.

A Low-Cost Contactless Transducer for the Measurement of DC Currents Up to 13 kA for the Industry of Anodized Aluminum

This paper is concerned with the development and the characterization of an ad hoc transducer for the contactless measurement of a high-intensity direct current (dc) for industrial applications. Specifically, the proposed transducer will be used to measure the oxidation process current in a continuous aluminum coil anodizing line (standard sulfuric acid anodizing). In this oxidation process, the current measurement is required to control the thickness of the obtained aluminum oxide, the most important parameter in determining the overall quality of the process. Starting from the features of the considered process, the transducer must measure, without contact, dc currents up to 13 kA in continuous aluminum strips, whose width and thickness can be up to 1600 and 5 mm, respectively; the mass of each coil can be greater than 4700 kg, and the length can be more than 800 m. The dc current is supplied by an ac/dc converter, but due to the features of the oxidation process, only a fraction of the supplied current flows in the aluminum strip and concurs to the oxidation process; the remaining current flows as a leakage current in the acid solution, creating undesired phenomena and energy losses. In this paper, we propose a low-cost current transducer, whose sensing element consists of an iron core equipped with two windings; the first excites the core, while the second is used to measure the variation in the magnetic saturation of the core due to the dc current to measure. The transducer output is conditioned by an electronic circuit that gives a continuous voltage proportional to the input current. A prototype of the proposed transducer has been designed and implemented; a series of characterization tests has been conducted, and the obtained results are discussed in this paper. The transducer is able to measure up to 13 kA, with an overall accuracy of 1.5% for currents over 11 kA.

Continuous Scan, a method for performing modal testing using meaningful measurement parameters; Part I

This paper presents the first part of a work about modal testing using meaningful measurement parameters. Scanning Laser Doppler Vibrometer (SLDV) systems are becoming largely used both in industry and university for performing vibration measurements. A reason for the success of SLDV systems can be found in their capability of measuring vibration remotely and under different environmental conditions which, when hostile, can inhibit other transducers to work correctly. Hence, SLDV system can be very practical and useful in many engineering applications. SLDV systems are being used as a contactless transducer measuring vibrations from a discrete number of measurement positions marked on the specimen whenever an optical access to it is available. Hence, the advantage of a modal test carried out using accelerometers and one carried out using a SLDV system can be: (i) the automation of the measurements and (ii) the increase of the spatial resolution of the measured modes. This suggests that SLDV systems can be used as a practical replacement of accelerometers operating the same measurement method. Continuous Scanning method is a novel approach of using contactless transducers for measuring vibrations. The most important difference between a discrete and a continuous approach is the method of measuring a vibration pattern. A discrete method measures the level of vibrations at discrete positions on a structure whereas a continuous method captures the modulation of the vibrations produced by the excited modes. This is possible when a transducer can travel across a vibrating surface. This first part of the work presents a new approach of continuous scanning measurement method using a multi-tonal excitation waveform. The paper starts from a comparison between a step and continuous scan mode to introduce a novel approach of continuous scan and multi-tonal excitation waveform. The objective of this first part of work is to present and understand that measurement parameters, such as measurement positions, and can be carefully chosen to improve the measurement technique. A laboratory test piece and a helicopter tail cone are used as examples for the application of this new measurement method approach.

Human temporal bones versus mechanical model to evaluate three middle ear transducers

A life-size mechanical middle ear model and human temporal bones were used to evaluate three different middle ear transducers for implantable hearing aids: the driving rod transducer (DRT), the floating mass transducer (FMT) or vibrant sound bridge, and the contactless transducer (CLT). Results of the experiments with the mechanical model were within the range of the results for human temporal bones. However, results with the mechanical model showed better reproducibility. The handling of the mechanical model was considerably simpler and less time-consuming. Systematic variations of mounting parameters showed that the angle of the rod has virtually no effect on the output of the DRT, the mass loading on the cable of the FMT has a larger impact on the output than does the tightness of crimping, and the output level of the CLT can be increased by 10 dB by optimizing the mounting parameters.

The use of eddy currents on the measurement of relative acceleration

The present paper describes a method for the measurement of linear or angular relative acceleration. It is based on eddy current generation in an electrically conductive component when submitted to the acceleration to be measured, under a static magnetic field. A prototype of a novel contactless transducer using that method is also presented. Experimental results of angular relative acceleration measurements are shown. Further advances on the transducer development are pointed out.

Ultrasonic model studies of Rayleigh wave scattering

The effects of surface irregularities on the propagation of Rayleigh waves are studied using two‐dimensional seismic ultrasonic models. Specially designed contactless transducers (Chamuel, U.S. Patent Number 4,035,762, July 1977), in the form of electromagnetic coils, were used to generate and detect the ultrasonic waves in magnetostrictive sheets. The contactless transductions are based on the Joule and Villari effects. One type of transducer consisting of a folded circular coil was used to detect the longitudinal component of the surface waves propagating along the edge of the magnetostrictive sheet. A second type of transducer was used to measure the body wave generated by the surface waves upon reflections from the surface irregularities. Several shapes such as steps, ramps, pyramids, and rectangular obstacles were machined along the edges of the magnetostrictive sheets. Nickel 200 was chosen for the experiments. The data obtained from the experiments clearly showed the transmission. reflection, and mode conversion of the wave at the boundaries. The dimensions of the surface irregularities were comparable to the dominant wavelength.

Contactless transducer for measuring torque

Contactless transducer for measuring torque

Analyzing the sensitivity of contactless transducers for electrometry

Analyzing the sensitivity of contactless transducers for electrometry