ОСОБЛИВОСТІ РОБОТИ НАДПРОВІДНОГО ОБМЕЖУВАЧА СТРУМУ ПРИ РАПТОВОМУ КОРОТКОМУ ЗАМИКАННІ

In the article the fault current limiter of inductive type with high-temperature superconducting coil and screen is considered. Main features of transient at occurrence of short circuit are analyzed.В статье рассмотрен ограничитель тока короткого замыкания индуктивного типа с высокотемпературными сверхпроводящими обмоткой и экраном. Проанализированы основные особенности переходного процесса при возникновении тока короткого замыкания.У статті розглянуто обмежувач струму короткого замикання індуктивного типу з високотемпературними надпровідними обмоткою та екраном. Проаналізовано основні особливості перехідного процесу при виникненні струму короткого замикання

ANALYSIS OF THE OPERATION PECULIARITIES OF THE SUPERCONDUCTING INDUCTIVE CURRENT LIMITER WITH ADDITIONAL SUPERCONDUCTING SCREEN

Purpose. The inductances of magnetic system of a current limiter for the nominal operating mode were determined. The aspects of functioning and a design of a superconducting short-circuit current limiter of inductive type with a superconductive main and additional screens, and superconductive winding, which are placed in a general cryostat on a ferromagnetic core, which ensures an improvement of magnetic field dissipation and in energy efficiency are observed. Methodology. The analysis of distribution of magnetic field of the short-circuit current limiter of inductive type with superconducting high-temperature coil and superconducting main and additional screens, using mathematical modeling by the finite element method in math software package FEMM for different modes of operation is carried out. Results. The calculations of magnetic field dissipation in operational modes are carried out. Originality. The investigations aimed to analyze the influence of distribution of the magnetic field in inductive short-circuit current limiter with superconducting additional screen on its operation modes. First calculation of the distribution of magnetic fields in different modes of operation for the short-circuit current limiter in the area between high-temperature superconducting screens. Practical value. The advantage of additional screen of superconducting short-circuit current limiter is to improve screening from dissipation of the magnetic fields of the magnetic system and reducing the power losses at nominal mode. Using the proposed methodology will identify options acceptable to the current limiter mode of operation

Low-temperature densification of Al-doped Li7La3Zr2O12 : a reliable and controllable synthesis of fast-ion conducting garnets

The application of Li7La3Zr2O12as a Li+solid electrolyte is hampered by the lack of a reliable procedure to obtain and densify the fast-ion conducting cubic garnet polymorph. Dense cubic Li7La3Zr2O12-type phases are typically formed as a result of Al-incorporation in an unreliable reaction with the alumina crucible at elevated temperatures of up to 1230 °C. High Al3+-incorporation levels are also believed to hinder the three-dimensional movement of Li+in these materials. Here, a new, facile hybrid sol-gel solid-state approach has been developed in order to accomplish reliable and controllable synthesis of these phases with low Al-incorporation levels. In this procedure, sol-gel processed solid precursors of Li7La3Zr2O12and Al2O3nanosheets are simply mixed using a pestle and mortar and allowed to react at 1100 °C for 3 h to produce dense cubic phases. Fast-ion conducting Al-doped Li7La3Zr2O12phases with the lowest reported Al3+-content (∼0.12 mol per formula unit), total conductivities of ∼3 × 104S cm1, bulk conductivities up to 0.6 mS and ion conduction activation energies as low as 0.27 eV, have been successfully achieved. The ease of lithium diffusion in these materials is attributed to the formation of dense cubic phases with low Al3+dopant ratios. This approach is applicable to Li7xLa3Zr2xTaxO12phases and opens up a new synthetic avenue to Li7La3Zr2O12-type materials with greater control over resulting characteristics for energy storage applications

FEATURES OF OPERATION OF A SUPERCONDUCTING CURRENT LIMITER AT THE SUDDEN SHORT CIRCUIT

In the article the fault current limiter of inductive type with high-temperature superconducting coil and screen is considered. Main features of transient at occurrence of short circuit are analyzed