Current-carrying conductors, properties

Properties and ratings of current-carrying conductors 30/919 Table 30.3 Multiplying factors for copper sections... 

Properties and current ratings for aluminium and copper conductors Current-carrying capacity of copper and aluminium conductors... 

The most likely CVD applications of these superconductors to reach the practical stage are coatings for semiconductor and other electronic-related applications. For 1 arger current-carrying applications, a superconductor coating over a metallic conductor such as copper may also become a practical design because of its advantage over a monolithic superconductor wire. It is able to handle current excursions and has better mechanical properties. 

Landauer proposed in 1957 the first mesoscopic theoretical approach to charge transport [176]. Transport is treated as a scattering problem, ignoring initially all inelastic interactions. Phase coherence is assumed to be preserved within the entire conductor. Transport properties, such as the electrical conductance, are intimately related to the transmission probability for an electron to cross the system. Landauer considered the current as a consequence of the injection of electrons at one end of a sample, and the probability of the electrons reaching the other end. The total conductance is determined by the sum of all current-carrying eigenmodes and their transmission probability, which leads to the Landauer formula of a ID system ... 

Ampacity A measure of the current carrying capacity of a power cable. Ampacity is determined by the maximum continuous-performance temperature of the insulation, by the heat generated in the cable (as a result of conductor and insulation losses), and by the heat-dissipating properties of the cable and its environment. 

In Table 30.1 we provide the general properties of aluminium and copper conductors. The table also makes a general comparison between the two widely used metals for the purpose of carrying current. 

The definition of the critical current of a multifilamentary composite or cable superconductor may lead to some difficulties when comparing the properties of different samples. Those difficulties can be solved by the adoption of standard definitions and measurement techniques [ ]. The maximum current that can be carried by a conductor cannot be specified by any criteria. This current is very dependent on the current-voltage characteristic of the conductor, the cooling conditions, and the operating conditions, which determine the losses during the current rise time. For the computation of hysteretic losses in a practical superconductor by means of the well-known formula, it is important to determine the actual values of the critical current density, which is very anisotropic. 

ELECTROLYTE SOLUTIONS are solutions of electrolyte compounds in pure or mixed solvents such that the solutions become electric conductors in which current is carried by the movement of ions. They exhibit specific properties due to the more or less complete dissociation of their solutes into ions. Aqueous electrolyte solutions are involved in numerous biological, biochemical, geological, and technical processes. Nonaqueous electrolyte solutions are intensively studied owing to unique properties for their application in various new technologies such as high-energy batteries, electrodeposition, nonemissive displays, solar cells, phase-transfer catalysis, or electroor-ganic synthesis. 

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