Round Conductors Research Articles

Further study on the characteristic impedance of a new transmission line of round conductor and parallel plane with a slit

A conformal transformation for the analysis of a transmission line consisting of a cylindrical conductor placed opposite a slit in an infinite flat plate is developed. The approximate and exact expressions in closed- form of the characteristic impedance for the proposed line based on assuming only a quasi-TEM mode propagating in the line are as exact as the conventional one cited.

Improved analytical modeling of conductive losses in magnetic components

The one well-known one-dimensional method for calculating the AC resistance of multilayer transformer windings contains a built-in orthogonality which has not been reported previously. Orthogonality between skin effect and proximity effect makes a more generalized approach for the analytical solution of AC resistance in windings possible. This includes a method to calculate the AC resistance of round conductor windings which is not only convenient to use, but gives more accurate answers than the basic one-dimensional method because the exact analytical equations for round conductors can be used. >

Analysis and application of NRD-guide excitors

In this paper, the NRD-guide excitors using a length of coaxial line which consists of a rectangle external conductor and a thin round inner conductor are presented, and the characteristics of the input impedances of LSE 11 o mode and LSM 11 o mode at the insertion points are analysed and calculated by using the method of the rector Green's function respectively. The computation results show that the mode excitors are able to improve the operating modes matching between NRD-guide and the quasi-TEM transmission line. The structures are suitable for fabrication LSE 11 o mode oscillator and LSM 11 o mode oscillator to compose millimeter wave NRD-guide integrated front ends. An example of an LSE 11 o mode oscillator in Ka-band is given. Its oscillation frequency and output power could be easily adjusted by changing the parameters of the excitor.

Predicting Galloping Amplitudes

The use of wind tunnel data, lift and drag, together with a method of analysis, leads to estimates of gallop amplitudes. No damping is considered. The nonlinear analysis is similar to the describing‐function method used in control system design. The method is convenient to use because it can account for effects of Reynold's number directly. Two bluff body shapes are chosen to illustrate the prediction method. The first shape is the square section. This is also compared with earlier results. The second shape is the simulated ice shape on a round conductor. The results compare favorably with previous work.

Exact solutions for rectangularly shielded lines by the Carleman-Vekua method

Exact solutions for the field of the TEM mode of rectangularly shaped round (or strip) conductors are obtained by solving linear, singular integral equations. There are no limitations on the dimensions or the proximity of the conductors to the shield. The authors consider only round conductors. The kernel of the integral equation in such problems is the Green's function G of a line source inside the shield, possessing a logarithmic singularity near the source point.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Estimating the size of disturbances due to conductor motion in superconducting windings

An abrupt conductor motion is one of the dominant origins of a premature quench in a high-performance, high-current-density, magnet. A model based on microscopic slip phenomena is proposed to estimate the disturbance energy due to conductor motion from the mechanical properties of the conductors and the winding configurations, and the stability of the conductor against the disturbance. Stability of a rectangular-cross-section conductor is better than that of a round-cross-section conductor. To improve the stability by reducing the disturbance energy, the aspect ratio (for the rectangular conductor) and the diameter (for the round conductor) must be increased. >

Development and Installation of BPA's New Generation Transmission Conductors

The Bonneville Power Administration (BPA) has developed a family of new generation conductors which promises to reduce transmission line life-cycle costs. These trapezoidal wire conductors reduce air void area by 80 percent over conventional round rod conductors, allowing a denser packing of conducting material and greater efficiency through increased conductance and/or reduced tower loads. The trapezoidal wire family is made up of nine conductors ranging in size from 1.0 to 1.8 inches; six are all aluminum and three are aluminum with steel reinforcement. The new conductors are expected to satisfy all of BPA's typical conductor requirements for new construction, rebuild, and reconductoring projects, where the economics of resistive losses dominate the design. This paper introduces the new conductor family and assesses its uses and limitations. It discusses design details; mechanical, stress-strain, creep, and self-damping characteristics; and conductor sizing, procurement, handling and sagging, savings, and lattice steel and wood pole applications. It also describes the first use of the trapezoidal wire conductor family on the BPA Boundry Integration/Reinforcement Project.

Development and Installation of BPA's New Generation Transmission Conductors

The Bonneville Power Administration (BPA) has developed a family of new generation conductors which promises to reduce transmission line life-cycle costs. These trapezoidal wire conductors reduce air void area by 80 percent over conventional round rod conductors, allowing a denser packing of conducting material and greater efficiency through increased conductance and/or reduced tower loads. The trapezoidal wire family is made up of nine conductors ranging in size from 1.0 to 1.8 inches; six are all aluminum and three are aluminum with steel reinforcement. The new conductors are expected to satisfy all of BPA's typical conductor requirements for new construction, rebuild, and reconductoring projects, where the economics of resistive losses dominate the design. This paper introduces the new conductor family and assesses its uses and limitations. It discusses design details; mechanical, stress-strain, creep, and self-damping characteristics; and conductor sizing, procurement, handling and sagging, savings, and lattice steel and wood pole applications. It also describes the first use of the trapezoidal wire conductor family on the BPA Boundry Integration/Reinforcement Project.

Polygonal Coaxial Line with Round Center Conductor (Comments)

In the above paper, the author presented an expression for the attenuation constant a of a polygonal coaxial line with round center conductor.

Update on the Development of Reduced Wall 138kV HPOF Cables and Joints for Re-Conductoring of Existing 69kV Lines on the Florida Power &amp; Light Company System

A reduced wall 138kV HPOF pipe-type cable having a 700 kcmil (355 mm2) compact round copper conductor and 348 mils (8.8 mm) of insulation and two types of joints have been developed for re-conductoring existing 69kV HPOF feeders utilizing 5 inch (127 mm) outside diameter pipes on the Florida Power & Light Company (FP& L) system. Laboratory test results on the cable and two joints, one employing hard paper and the other high density crepe paper tapes, are reported. The commercial cable installation is described. Test results are also given on an improved design reduced wall 138kV HPOF pipe-type cable having a 2000 kcmil (1015 mm2) compact segmental copper conductor and 379 mils (9.6 mm) of insulation and a high density crepe paper joint intended for re-conductoring a 69kV HPOF pipe-type feeder using the existing 6-5/8 inch (168 mm) outside diameter pipes. The cable and joint satisfactorily passed all requirements of AEIC CS2-82 (4th Edition) [4].

A finite element method for analysing skin effect in conductors with unknown values of surface boundary conditions

AbstractThis paper presents a method of analysing the distribution of a two‐dimensional electromagnetic field in a conducting medium of known cross‐section carrying sinusoidal current and of unknown numerical values of boundary conditions on conductors surfaces. The method combines the finite element and separation of variables methods. An example is given of application of the method to calculation of impedance and electrodynamic forces of two thick, full and round conductors carrying oppositely directed sinusoidal currents. On the basis of numerical computation, graphs of resistance, reactance and electrodynamic forces are plotted.

A New Transmission Line of Round Conductor and Parallel Plane with Symmetrically Placed Slit (Short Paper)

A new transmission line consisting of a cylindrical conductor symmetrically placed opposite a slit in an infinite flat plate is formed by inversion from the fine of parallel plates of equal width. The characteristic admittance of the proposed line and one possible application of which is given.

Polygonal Coaxial Line with Round Center Conductor (Short Paper)

The complex potential function W = A (In z + C /sub n/z/sup n/) generates a zero-potential line approximating a regular polygon of N sides very closely, except in the nearly field-free region. By means of this function we work out the characteristic impedance, the power-carrying capacity, and the attenuation constant of the polygonal line of N sides wtth a round inner coaxial conductor in a closed form of elementary functions with good accuracy compared to more complex solutions. Results for N = 3 are believed to he nearly as good as those available in the literature.

Slotless-disc alternator with AC-side excitation

The paper examines a version of the double-disc alternator with AC-side excitation that uses a slotless stator. It is an interesting form of slotless machine because Gramme ring windings can be wound automatically on the strip-wound circular core and produce a mechanically secure unit. A basis for the design of this form of machine is described, and the main considerations which influence the choice of a suitable geometry are discussed. Experimental results demonstrate that the performance of the machine is satisfactory. Predictions of direct- and quadrature-axis reactances and full-load field current by standard synchronous machine methods are also adequate. A particular feature of the machine, the absence of stray loss in the solid rotor due to stator-slot permeance variations, is seen to be particularly beneficial. Eddy-current losses in the stator windings exposed to the main airgap field are examined and are shown to be relatively small but measurable. Methods of predicting these losses for round and rectangular conductors in both sinusoidal and uniform airgap fields are presented.

Losses in composite superconductors at a high level of magnetic field excitation: Part 2

Abstract At relatively high amplitudes and variation rates of a transverse external field, the saturated zone may occupy a considerable part or the entire space of the composite. Differential equations have been derived which enable one to calculate the time dependence of the magnetic moment of screening currents in a round composite conductor under these conditions. This dependence helps, the calculation of losses for different external field variation signals.

Losses in composite superconductors at high levels of magnetic field excitation: part 1

At relatively high amplitudes and variation rates of a transverse external field, the saturated zone may occupy a considerable part or the entire space of the composite. Differential equations have been derived which enable one to calculate the time dependence of the magnetic moment of screening currents in a round composite conductor under these conditions. This dependence helps, the calculation of losses for different external field variation signals.

Theoretical and experimental study of magnetic instabilities in multifilamentary Nb-Ti superconducting composites

Classical adiabatic stability criteria appear to be pessimistic for multifilamentary composites. The thermal conductivity K, the magnetic and thermal diffusivities D m and D θ , the heat transfer coefficient h k play a leading part in the determination of a stable composite. The differential magnetic and thermal equations have been solved and typical stability curves are given for either the slab model or the round conductor. Measurements of the quenching currents, in different magnetic, thermal and cooling conditions, for two meter long non inductive coils are made. The results are in good agreement with the theoretical predictions.

Complex Representation and Computation of Two-Dimensional Magnetic Fields

The method of evaluating two-dimensional fields as analytic functions of a complex variable without resort to absolute values and complex conjugates is described and applied to the magnetic field produced by straight currents. Explicit formulas are derived suitable for numerical computation of vector and scalar potentials, of field components, and of field gradients for round and polygonal (including rectangular) conductors, current ribbons, and arrays thereof.

Magnetic field strength in oersteds near large rectangular conductors

A high value of direct current in a conductor produces a high magnetic field which may affect electromagnetic instruments and control gear in the vicinity. The value of the magnetic field in oersteds at a distance d in feet, from the center of a large round conductor, solid or tubular, carrying a current of I amperes is given very simply by the equation, $H = 0.00656 \, I/d \eqno {\hbox{(1)}}$.

Proximity effect in solid and hollow round conductors

Proximity effect in solid and hollow round conductors