Conductor Selection Research Articles

Leadership and co-operation in orchestras

The leadership of musicians by the conductor of an orchestra is a combination of authority and charisma. It is a special case of directive-charismatic leadership that needs to be explained because it involves substantive restriction of freedom for the led, whereas in other creative fields (e.g. research and development) a non-directive style of leadership is considered functional to success. Current theory on leadership (e.g. contingency theory) is not able to explain this phenomenon. We develop a model of leadership in the orchestra, from which a specific (directive-charismatic) leader behavior is to be derived from the singularities of this leadership goal and the behavior required of followers. On the basis of a sample of n=334 musicians from thirty German orchestras, we show empirically that directive-charismatic leadership in the orchestra has a positive impact on the quality of ensemble playing, thus promoting artistic quality as leadership success. Conclusions are drawn both for leadership theory and for the selection and training of orchestral musicians and conductors.

Optimal conductor selection for radial distribution systems

Abstract In this paper, an algorithm is proposed for selecting the optimum size of conductors of feeder sigments of radial distribution networks. The optimal size of conductor determined by load flow method is applied to the optimal distance radial distribution network. The conductor, which is determined by the proposed method, will maximize the total saving in cost of conducting material and cost of energy losses and maintain acceptable voltage levels in radial distribution systems. An attempt has been made to reduce the losses in the existing radial distribution networks by optimizing the size of the branch conductor. The effectiveness of the proposed method is illustrated with suitable examples.

Optimal selection of conductors for distribution feeders

Designing a distribution system requires many stages of planning and rigorous calculations. Selection of conductors for design and upgrade of distribution systems is an important part of the planning process. An ideal conductor set should have the most economic cost characteristics, sufficient thermal capacity in the largest conductor to take care of situations with very high load and it should provide proper voltage at the farthest end under peak load conditions. In this paper, a method for selection of optimal set of conductors is presented. Several financial and engineering factors are considered in the solution. The intent is to arrive at a solution, which will be the most economical when both capital and operating costs are considered. Simulations have been performed to obtain results based on different criteria and the results are compared.

Optimal Selection of Conductors for Distribution Feeders

Designing a distribution system requires many stages of planning and rigorous calculations. Selection of conductors for design and upgrade of distribution systems is an important part of the planning process. An ideal conductor set should have the most economic cost characteristics and sufficient thermal capacity in the largest conductor to take care of situations with very high load, and it should provide proper voltage at the farthest end under peak load conditions. In this paper, a method for selection of an optimal set of conductors is presented. Several financial and engineering factors are considered in the solution. The intent is to arrive at a solution that will be the most economical when both capital and operating costs are considered. Simulations have been performed to obtain results based on different criteria and the results are compared.

Electrical contact overheating under short-circuit currents

Abstract In this paper, a method is proposed, concerning the temperature rise estimation at stationary electrical contacts, operating in the power supply network, during short-circuit. The method consists in the formation of a mathematical model, which simulates the operation of the contact/conductors system under heavy fault currents. The model comprises analytical mathematical expressions that enable temperature estimations lengthwise the aforementioned system. From the analysis results, it can be concluded that the conductor (bar) cross-section is of primary importance as far as overheating is concerned. It is convincingly shown that the equipment deterioration can be delayed by lowering the maximum contact temperature during short-circuit transient phenomena. An approximate equation is also proposed as an extra calculating test for the contact and bar overheating under short-circuit conditions. The proposed model could be a criterion for the selection of conductors and switchgear components.

Evaluation of Tensile Strength of Multistrand Conductors—Part I: Theoretical Basis

A simple model was developed to predict the plastic behavior of a stranded conductor under tensile loading to fracture. Two cases are considered; the torque transmitted in the case of conductors with fixed extremities and the rotation angle in the case of free rotating conductors. The permanent set caused by bending and torsion during the stranding process associated with conductor fabrication was taken into consideration. The model predicts maximum failing load and total elongation, parameters currently used for design and selection of conductors.

Optimum long-term planning of a radial primary distribution network: Part I: Data description and first proposed network form

An algorithm for the technoeconomically optimum longterm planning of a radial primary power distribution network, dealing with the proper conductor selection for the network segments, is, proposed in this article which is completed in two parts. Load data (annual growth, load distribution), necessary economic functions and technical constraints (thermal conductor capacity, permissible voltage drop, thermal short-circuit conductor strength), which are taken into account during the planning procedure, are given in this Part L New quantities, such as the long-term economic conductor capacity and sets of allowable conductor selections for every network segment, accompanied by their possible replacement years, are also determined in this part. A network form is finally proposed as the first step of the long-term planning; procedure, which is completed in the following Part II.

Audible noise performance of 6-rail conductors on a 765-kV double circuit test line

To satisfy an annual rate load growth of approximately 10% per year, Korea Electric Power Corporation (KEPCO) has been studying the use of double circuit 765-kV transmission lines. Since this would be the first application in the world for such lines, a 765-kV test line was built near the Yellow Sea to gain experience with this higher voltage. A primary corona phenomena that is important for conductor selection is audible noise (AN) due to corona. This paper presents the results of long-term measurements of AN from the 765-kV double circuit test line using a bundle of 6-483.8 mm/sup 2/ conductors at Korea Electric Power Research Institute's (KEPRI) 765-kV test station. The analysis of the data shows that the 6-rail conductor bundle satisfies the AN criterion of 50 dB(A) under rainy weather conditions.

Design of SMES with reduced stray field

A design for an improved 50 kWh SMES arrangement was made concerning the selection of an appropriate conductor, the determination of forces, efficient quench protection and mechanical strength calculation. The improvement relates to a drastic reduction of the magnetic stray field. This goal can be obtained by adding a second or even a third solenoid in such a way that the magnetic moments of all solenoids neutralize each other. Various methods to reduce the stray field were discussed and then the most promising solution-the one which produces the smallest magnetic stray field in combination with acceptable geometrical dimensions and conductor amounts-was analysed for further design. The coil calculation was based on a typical NbTi superconductor in order to match its critical data with the results of the optimized coil configuration.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A preliminary design for a one GHz NMR spectrometer magnet

We have performed a preliminary design for a persistent GHz NMR magnet at 23.5 T and 1.8 K operating conditions. In this paper we shall address the issues of realistic conductor selection, the coil design, the magnetic and mechanical analysis of the coil, and the required field uniformity. In addition, we shall describe the GHz magnet cryostat with a practical 1.8 K J-T refrigerator system. Finally the vibration isolation system and field shield design and its associated field harmonics will be analyzed. >

Design aspects of mid-size SMES using high temperature superconductors

Conceptual designs of modular, cold-supported superconducting magnetic energy storage (SMES) units using high-temperature superconductors (HTSs) were investigated over the mid-size energy range of 2 to 200 MWh. This size range covers many utility, industrial, and military applications. Both toroidal and solenoidal configurations were analyzed to determine physical dimensions, heat loads, and cost of major components. Among the effects considered were the impact of critical current density on feasible configurations, mass of conductor, and cost: the effects of magnetic field and strain limits on physical parameters and structural mass; and the savings in refrigeration from operating at a higher temperature. The design of the HTS conductor, stability criteria, and coolant selection are also discussed. >

SMES conductor selection: an engineering perspective

The authors discuss the engineering considerations driving the selection of a conductor concept for large-scale SMES (superconducting magnetic energy storage). There are five areas that require special attention: current diffusion effects, stability margin, AC losses, cooldown stress sustained by the conductor, and helium containment. From a magnet design perspective, there is a strong premium in SMES on utilizing conductors with as high a current as possible. It is difficult to scale up a particular monolithic design to achieve higher current. Overall magnet design issues are also more difficult to tackle with monolithic conductors. It is concluded that cable-in-conduit conductors are more attractive for large-scale SMES. >

Research and development of superconductors and superconducting coils for the Large Helical Device

Superconducting conductors and coils were developed for the Large Helical Device. The critical current and cryogenic stability of a 22 kA class pool-boiling conductor were measured to generate engineering data for the design of helical coils. Six superconducting R & D coils were fabricated and tested to verify the conductor selection and coil structure for helical and poloidal coils. A forced-cooled poloidal research coil has been tested successfully; the measured stability margin and limiting-current data can be interpreted with well-known theories of forced-flow cooled conductors. The test results validate the basic design parameters used in the design of the full-scale superconducting magnets for the Large Helical Device.

Anodised Aluminium as an Alternative Substrate for High Power Hybrid Microelectronics

An investigation to evaluate the suitability of anodised aluminium as a substrate material has shown that the relatively high coefficient of thermal expansion of the aluminium caused the brittle cermet resistors to craze giving rise to unstable resistance values whereas PTF resistors appeared to suffer no ill effects. The work was implemented in conjunction with selection of low temperature thick film conductor and resistor inks to achieve the optimum combination of anodised aluminium substrate and ink system. These inks were then printed and fired on anodised aluminium, aluminium nitride and alumina substrates, and the physical and electrical properties of the inks and substrates compared. A combination of modest success, employing polymer resistors and cermet conductors, produced viable circuits with resistors of reasonable stability. A low power hybrid device, with surface mounted components, was employed to further validate the substrate/ink combinations in ongoing tests.

Optimal conductor selection in planning radial distribution systems

A fast algorithm to help in the selection of proper conductors for feeder expansion plans is presented. The optimal conductor type is determined for each feeder segment in order to maintain an acceptable voltage profile along the entire feeder, minimizing capital investments and the cost of feeder losses. Lateral branches as well as regulators along the feeder are considered. Computer implementation of the algorithm is described. Its use in conjunction with an optimization model for configuring feeder networks to derive an overall distribution expansion plan is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A parametric system study for the selection of RFP fusion reactor design point

Based on simple physics, engineering, and economic models among various design parameters of reversed-field pinch (RFP) fusion reactors, a parametric system study program has been developed giving cost of electricity (COE) for a given set of design parameters or a set of design parameters giving the minimum COE. This program has been used extensively to select design points and evaluate the sensitivity of physics, engineering, economic and operational parameters in the REPUTER RFP fusion reactor design study effort. Several key features emerged from the study in relation to high power density RFP fusion reactors with solid breeder blanket. They are: (1) selection of normal conductor for TF and PF coils to reduce the thickness of radiation shielding, (2) selection of a total first wall loading of 18 MW/m 2 considering the potential economic merit and nonlinear effects which might shorten the lifetime of the first wall, and (3) a maintenance policy of package replacement of the fusion power core, including TF coils, to significantly reduce maintenance time. The uncertainty range of COE was evaluated based on the sensitivity and uncertainty of design variables and parameters. The result warned us of the use of COE evaluated in this program for the purpose of comparison of economy with the result of other fusion system studies.

Transmission Line Optimization

Transmission line designs have been optimized for many years through comparative estimates of the present worth of revenue required (PWRR), in order to achieve design performance at minimum cost. The method has most commonly been used for conductor selection, but can obviously be applied to other parameters as well, although the economic returns from these other parameters are largely unknown. Since many of the variables in a line design are strongly interactive, calculation procedures containing comprehensive cost models are required if comparisons are to be valid for anything beyond simple design changes. Such a methodology has been developed and used to explore the sensitivity of the PWRR to several design variables.

Guidelines for the selection and operation of bare ACSR conductors with regard to current-carrying capacity

Factors affecting the thermal ratings of bare overhead power conductors (in particular, ACSR conductors) are reviewed. Equations for calculating the current-carrying capacity (ampacity), loss of strength, and time-temperature characteristics of ACSR conductors are illustrated and parameters used in these equations are explained. Results have been obtained for ampacity, loss of strength and conductor temperature for a typical ACSR conductor (‘Drake’) in terms of various parameters such as ambient temperature, wind velocity, and (solar) insolation by means of Fortran programs written by the authors. These results are presented in graphical form. From them, meaningful conclusions are drawn regarding the means of evaluating permissible loading levels of transmission and distribution lines, especially lines of short to moderate length. The paper has been written primarily from the standpoint of showing how information currently available to utility industry personnel can be applied to evaluate the impact of various parameters on the permissible loading levels of bare conductors. The examples presented are typical of those of interest to the Tucson Electric Power Company and other utilities.

Comparison of Enameled Steel Substrate Properties for Thick Film Use

Porcelain enameled steels have had a long history of industrial, structural and related applications. Recent interest in such materials has centered on electrical uses as a substrate for hybrid circuits, additive printed wiring, and packaging. A study of some of the critical properties of available enameled steels was undertaken.Five types of enameled steel substrates from three manufacturers were tested. The electrical properties studied included dielectric constant, dissipation factor, voltage breakdown, surface and bulk insulation resistance. The effect of humidity on the insulation resistance of the enamel coatings themselves was compared. The influence of the thermal conductivity of the substrates was also examined.The properties of a thick film resistor system was determined on the various enamel steel substrates. The properties tested included resistivity and TCR firing sensitivity.The effect of the type of substrate on the properties of a selection of thick film conductors was determined. Conductivity and gold and aluminum wire bond strength were compared on the various substrates.The dielectric properties of a multilayer/crossover dielectric thick film material were compared among 96% alumina, soda‐lime glass and the various enameled steel substrates.Many individual differences between the enameled steel substrates were found. However, all of the substrates could be utilized to produce satisfactory thick film circuits when the proper choice of thick film materials was made.Continuing changes, improvements and additional sources of supply are expected to overcome some of the present shortcomings. These should enhance the use of such substrates for large area uses and lower cost applications.

Conductor systems for overhead lines: some considerations in their selection

The selection of conductors for a modern overhead transmission or distribution system is an exercise in optimisation and balancing of conflicting requirements. Service experience and environmental considerations may often challenge established concepts for the design of future lines. The reasons for the predominance of aluminium-based conductors are outlined, and the wide available range of such conductors and the properties of each main variant are described. The influence of manufacturing processes in conductor design is set out, and the important role played by greasing is emphasised. These considerations are shown to lead to the selection of particular conductors in each of the voltage bands from 1.v. to u.h.v. Factors discussed include load density and growth, climatic environment, strength, standardisation, corrosion, external loading, corona effects and economics. The paper proceeds to describe the effects of aeolian vibration, subconductor oscillation and galloping on the choice of conductor and fittings, and on conductor bundle geometry. The rather different emphasis in choosing conductors for distribution systems is also discussed and the overriding need for standardisation stressed. The need for conductor-material specifications and acceptance testing is recognised, and the paper concludes with a brief outline of possible future trends in conductor engineering.