Effect Of Mutual Inductance Research Articles

Active Control of Small Actuator for Moving Head of Video Cassette Recorder.

An ultra small actuator for the moving magnetic head in the DTF (Dynamic Track Following) system in VCRs has been developed. This actuator is the moving-coil type, utilizing cylindrical permanent magnet. The DTF system consists of an actuator and a servo control system. In order to achieve DTF system with high performance, it is necessary to improve the mechanical vibration characteristics of the actuator. This paper deals with the design method of the active vibration control loop using the velocities and displacements of a moving magnetic head. These physical quantities are measured by means of a moving sensor coil installed near the driving coil. In this construction, the alternating current caused by mutual inductance effect led to the sensor coil plays an important role in the active vibration control loop, and it is shown experimentally that a velocity and displacement feedback control loop which accounts for these influences can reduce mechanical vibration.

Digital model for transient studies of a three-phase five-legged transformer

A flux linkage model for a three-phase five-legged transformer is derived for the first time. The effects of mutual and leakage inductances, saturation, eddy current loss, hysteresis and residual fluxes of the nonlinear iron core are included. A straightforward and novel method for determining both the apparent and incremental inductance matrices for a loaded two-winding five-legged transformer is derived. Simulations presented in this study are based on apparent inductance (λ/i) rather than incremental inductance (dλ/di) because this approach was found to be preferable for predicting the behaviour of the laboratory transformer used. Eddy current and hysteresis losses are combined into one core loss term which is accounted for by a voltage-dependent resistance load on the secondary. The flux in each segment of the iron core and in the air gaps and tank are computed at each step. The model thus yields a completely detailed description of the transformer's behaviour. A predictor-corrector algorithm written in FORTRAN is used to solve the set of nonlinear differential equations that describe the transformer. A 386-based computer has been used to generate voltage and current waveforms faithful to laboratory data. Transformer inrush current and ferroresonance are selected as test cases because of the extreme computational demands that these transients place on the computer model. The model can be implemented using only nameplate and conventional test data along with the B-H curve of the core material. The method is thus well suited to the practical needs of engineers in industry.

Bond-polarisability tensors for the group IVB elements

A valence-optical scheme of additive polarisability tensors is presented for bonds of the Group IVB elements. Constituent bond additivity is affected but not seriously impaired by the effects of mutual induction over the substantial range of mono- and poly-halogenated compounds studied. Regular trends are observed in the bond-polarisability anisotropies and in the directional polarisabilities.

Polarized infrared study of anilinium-vermiculite intercalate: II. Frequency shifts and dipole interactions

In terms of the model for Llano anilinium-vermiculte intercalate proposed in Part I of this series, (M. Raupach and L.J. Janik, J. Colloid Interface Sci. 121, 449 (1988)) mutual dipole induction and surface dipole image effects explain the detailed band structure and frequency shifts observed over two ranges (3750–2550 and 1590-1550 cm −1 of the infrafed spectrum. The induction effects were estimated from polarizabilities and the distance between the interacting dipoles. The polarizabilities depend on the composition and charge of the interacting groups. Sets of two and eight frequency shifts (∼30 cm −1) were associated with the interaction of NH with charged and uncharge (respectively) inner OH from the octahedral sheet of the clay. Two furthers sets of IR bands, cach having larger frequency shifts (∼230 cm −1), were related to the interaction of -NH 3 with water and to the interaction of NH with the charged surface oxygens of the clay. The NH bending modes gave an obvious split producing bands of differing polarization with respect to the clay surface. The magniture of this was estimated, using surface dipole images, from the interdiple distance of the adsorbate dipole units, their radius, the dipole-image distance, relevat dielectric constants, and the transverse optical phonon frequency of the adsorbate. The dipole images were found to be set up close to tetrahedral substitution sites in one vermiculite and somewhat toward the octahedral layer from those sites in a second vericulite. Transverse optical phonon frequencies were found to support the idea of resonance between the absorbate and the clay and hence Model 2 proposed in Part I.

Simulation of electric arc with hysteresis during discharge of a fusion superconducting magnet system

Simulation of an internal voltage induced arc strike and attendant voltage-current hysteresis characteristics in an FED/INTOR scale superconducting magnet and circuit protection system during discharge was performed. To begin, an analytical solution was used to investigate system response for an internally shorted magnet and simplified circuit protection system during magnet discharge. The short produced a current split within the magnet resulting in a transformer like mutual inductance effect. Thus, the coupling coefficient was introduced in the equations to be physically realistic and to prevent degeneration of the associated eigenvalue problem. The effects of varying short resistance, dump resistance, and number of coil turns shorted are presented. This led to simulation of an arc strike, including hysteresis effects, which is then compared to the usual constant resistance used to simulate magnet shorts. Tracking of arc characteristics was made possible through specially developed multiple tripping capabilities recently incorporated into MSCAP (Magnet Systems Circuitry Analysis Program) for safety and instrumentation control simulation.

INTERACTION BETWEEN THE CARBONYL GROUP AND A SULFUR ATOM. PART XI PHOTOELECTRON SPECTRA OF SOME 2-ALKYLTHIOCYCLOPENTANONES

Abstract The helium I photoelectron spectra of some 2-alkylthio-cyclopentanones are reported. The IP′s related to the sulfur and carbonyl lone pairs are compared to those in the corresponding cyclopentanones and cyclopentyl alkyl sulfide. The observed stabilization of both orbitals cannot be explained by the mutual inductive effects of the sulfur and carbonyl group. The conformational dependence of this effect is discussed.

A mutual inductance shocker

A simple dc shock-generating device is described. The principle of operation relies upon the mutual inductance effect between the primary and secondary coils of a transformer.

EFFECT OF UNEQUAL MUTUAL COUPLINGS OF SYNCHRONOUS MACHINE ON ITS DYNAMIC RESPONSE

Abstract In the conventional models derived for the synchronous machine, it is assumed that all the mutual couplings on each of the direct and quadrature axes are equal. This assumption is satisfactory for calculation of the armature quantities, but it is insufficient in calculating the field circuit quantities. Hence, an extra mutual inductance is considered between the field and the damper winding. The model parameters are derived and the effect of the extra mutual inductance is obtained on the eigenvalues of the short-circuit model and the model of a synchronous machine connected to an infinite-bus.

Molecular geometry and the intramolecular hydrogen bond in a vicinal diol: comparison of the molecule in solution and in the solid and isolated states.

Quantum chemical calculations show that the O-C-C-O dihedral angle of 3,3-dimethyl-tricyclo-[6,4,0,02,7]-dodeca-6-ene-di-1,2-o1 does not depend on steric interactions, This angle is the same for molecules in the solid state (X-ray diffraction), in solution (infrared spectroscopy) and isolated (theoretical calculations). Its value minimizes the total energy of the molecule, and particularly that due to the mutual inductive effects of the hydroxyl groups of the diol.

Mutual induction between the E- and the D-layers of the ionosphere during a solar flare

A substantial part of the ionospheric currents flows in the D-layer during a solar flare although the quiet-time Sq currents are confined mostly in the E-region. In this article we study the mutual induction effect between these two layers and its effect on the ionospheric currents. We set up equations for the currents in the E- and the D-layers respectively; both self induction and mutual induction are taken into account. The transient currents are analytically solved—following an iterative perturbation approach—in terms of the quiet time currents and the transient electron densities. It is observed that: 1. (i) the mutual induction current in the E-layer is comparable to the self induction current; 2. (ii) the currents due to induction are comparable to the non-inductive dynamo field; 3. (iii) the induction effect in the D-layer is negligible; 4. (iv) the inclusion of mutual induction will improve the theoretical calculation of the time lag between the crochet maximum and other Sudden Ionospheric Disturbances as well as of the time lags among the maximum phases of crochets all over the world.

The Effect of Mutual Inductance and Mutual Capacitance on the Transient Response of Braided-Shield Coaxial Cables

A quantitative comparison is made of the importance of mutual inductance and mutual capacitance in the leakage of transient signals through the braid of a coaxial cable. The difference between mutual inductance and mutual capacitance coupling is vividly exhibited in the transient predictions. Comparisons of predictions to measurements made on a length of RG-214 test cable are also included.

The Calculation of Geophysical Induction Effects Using Surface Integrals

Summary Two iterative methods, originally proposed by Price, for calculating electromagnetic induction effects in thin non-uniformly conducting sheets, are here extended to include mutual induction effects when a second conductor is present. The applicability of either method in a given problem depends on the resistivity of the conductors, and on the variation of the inducing field, and conditions for convergence are given. At each stage of the iteration, relations are required between the field components and streamline functions for the induced current systems. These relations have been expressed in surface integral form in a previous paper, in place of the usual spherical harmonic expansions, and it is shown that the integrals may be evaluated accurately. An indication of the accuracy of the iteration process is obtained by applying the method to a problem for which an analytic solution is known. As a preliminary to the study of induction in the oceans, the method is then applied to the problem of electromagnetic induction in a hemispherical shell, representing the Pacific Ocean, surrounding a concentric perfectly conducting sphere.

Surface Integral Formulae for Geomagnetic Studies

Many geomagnetic studies are concerned with time-varying magnetic fields at the Earth’s surface, and their relation to electric current systems in the upper atmosphere and in the Earth. There are, for example, many recent (as well as many earlier) studies of the Solar and Lunar diurnal variation fields, and of the ionospheric and earth current systems associated with them. These studies have led to the development of various methods and formulae for separating the surface field into parts of external and internal origin, and for determining the ionospheric currents that correspond to the external part. Further, the relationship found between the fields of internal and external origin is of the form that would be expected if the earth currents were due simply to electromagnetic induction by the moving and varying ionospheric current systems. A study of this relationship can lead to information about the conductivity of the Earth at various depths. This requires the solution of various mathematical problems on the electromagnetic induction of currents in concentric spheres and spherical shells of non-uniform conductivity, and involves the evaluation of self and mutual induction effects in these conductors. One of the important problems is to estimate the influence of currents induced in the relatively highly conducting oceans, and the screening effects of these currents on the conducting layers of the earth below. In the earlier studies the current systems and magnetic fields were expressed in terms of series of spherical harmonics and many valuable results were obtained in this way. When, however, it is desired to study detailed features of certain fields, such as the great enhancement of the Sq field near the dip equator, or, again, when one attempts to solve an induction problem which has, as one of the conductors, a thin shell with abrupt changes in conductivity, as at the surface of the Earth, then this method leads to difficulties owing to the slow convergence of the spherical harmonic expansions required. In the solution of such induction problems, the numerical work involved in solving the infinite sets of simultaneous equations, that are found for the coefficients of the required spherical harmonic expansions, is often prohibitive, and the solution obtained by truncating the series at a point that would make the numerical work possible very inaccurate. (See for example, the discussion by Ashour (1965a) of a problem considered by Rikitake & Yokoyama (1955)). Hence, alternative methods of treating these problems have been sought.

Correction factors of deflectional wattmeters

The paper deals with the ordinary ironless wattmeter and the correction factors (due to the effect of mutual inductance between the current and voltage coil and the effect of the nature of the load) that should be applied to its indication. As the mutual inductance between the current and voltage coils changes its sign from negative to positive as it passes through zero, the correction factors differ in the first part of the scale from those in the second part. An attempt is also made to show that the device which consists of a coil in series with the voltage coil, and wound closely with but in opposition to the current coil and intended to compensate for the power loss in the voltage coil circuit, is of very limited value on alternating current. Correction factors which take into account all the relevant effects are calculated in the paper.

Analysis of Nonreciprocal Effects in an N-Wire, Ferrite-Loaded Transmission Line

The N-wire rotationally symmetric transmission line surrounding a thin ferrite rod is analyzed here with the aim of determining the feasibility of this low-frequency nonreciprocal device. The structure is assumed to be infinitely long. The transmission line equations are solved in which the effect of mutual inductances and capacitances between wires and the perturbing effect of the ferrite are taken into account An expression for the rotation per unit length of line is obtained as a function of the structure geometry, the magnetic condition of the ferrite, and the operating frequency. The result is valid for thin wires and thin ferrite rods. Two examples are given. The four-wire line (gyrator) is evaluated for a ferrite radius equal to 1/16 the structure radius and the result is a predicted rotation of 0.76°/cm at 1000 mc for a 500 gauss magnetization ferrite. Somewhat larger rotations than this were obtained experimentally by Rowen who worked with larger diameter ferrites where the perturbation theory developed here would not be expected to apply. The eightwire line (circulator) is also evaluated on the basis of the theory and the analysis indicates that rotations of the order of 4°/cm should be obtained at 1000 mc for a 500 gauss ferrite at similar operating conditions.

Phase-comparison carrier-current relaying system

SINCE ITS INTRODUCTION 6 years ago, phase-comparison relaying has enjoyed wide acceptance. As originally conceived, its field of application was to be largely for medium-length, 2-terminal overhead lines. The operating experience has been so good that the demand has grown for extending its field of application to longer lines, to 3-terminal lines, and to certain cables. Also, its inherent immunity to the effects of mutual inductance makes its use attractive for ground-fault protection even though it may not be applicable for phase-fault protection. In such cases, there was a need to combine the virtues of phase- and directional-comparison relaying. Modifications now have been made to phase-comparison relaying equipment that will provide these desired extensions of its field of application. See Figure 1.

The effects of mutual induction between parallel transmission lines on current flow to ground faults

The effects of mutual induction between parallel transmission lines on current flow to ground faults

The effects of mutual induction between parallel transmission lines on current flow to ground faults

The effects of mutual induction between parallel transmission lines on current flow to ground faults

The Effects of Mutual Induction Between Parallel Transmission Lines on Current Flow to Ground Faults

THIS paper is intended to present some of the problems encountered in determining unbalanced fault currents and unusual results that may be expected on systems with parallel lines on a common right of way. Correct results are required so that proper co-ordination and application of relays may be accomplished. Fault studies must be made and constantly revised, as a power system changes and expansions take place. Also, future conditions must be studied so that intelligent selection may be made of circuit breakers and current transformers. It is the purpose of this paper to discuss

Cable Crosstalk-Effect of Non-Uniform Current Distribution in the Wires

When wires are close to each other as they are in cable, the mutual inductance coupling between pairs is not a simple number, constant at all frequencies. Because of the non-uniform and non-symmetrical distribution of current over the cross-sections of the conductors the “effective mutual inductance” is of the form M = M <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</inf> + jM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</inf> where both M <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</inf> and M <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</inf> vary with frequency. This paper discusses the results of certain measurements which have been made of the effective mutual inductance between straight wires and between cable pairs over a wide range of frequencies extending up to a million cycles. This is of interest in connection with crosstalk problems in cable carrier telephone systems.