scholarly journals The Effect of Insulation Characteristics on Thermal Instability in HVDC Extruded Cables

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 550
Author(s):  
Bassel Diban ◽  
Giovanni Mazzanti
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Electric Field ◽  
Temperature Rise ◽  
Thermal Instability ◽  
Analytical Calculation ◽  
High Voltage Direct Current ◽  
Stability Diagrams ◽  
High Dependency ◽  
Insulation Thickness

This paper aims at studying the effect of cable characteristics on the thermal instability of 320 kV and 500 kV Cross-Linked Polyethylene XLPE-insulated high voltage direct-current (HVDC) cables buried in soil for different values of the applied voltages, by the means of sensitivity analysis of the insulation losses to the electrical conductivity coefficients of temperature and electric field, a and b. It also finds the value of dielectric loss coefficient βd for DC cables, which allows an analytical calculation of the temperature rise as a function of insulation losses and thermal resistances. A Matlab code is used to iteratively solve Maxwell’s equations and find the electric field distribution, the insulation losses and the temperature rise inside the insulation due to insulation losses of the cable subjected to load cycles according to CIGRÉ Technical Brochure 496. Thermal stability diagrams are found to study the thermal instability and its relationship with the cable ampacity. The results show high dependency of the thermal stability on the electrical conductivity of cable insulating material, as expressed via the conductivity coefficients of temperature and electric field. The effect of insulation thickness on both the insulation losses and the thermal stability is also investigated.

scholarly journals Enhanced electrical conductivity and mechanical properties in thermally stable fine-grained copper wire

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Qingzhong Mao ◽  
Yusheng Zhang ◽  
Yazhou Guo ◽  
Yonghao Zhao
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Yield Strength ◽  
High Speed ◽  
Copper Wire ◽  
Rapid Development ◽  
Dislocation Slip ◽  
Ultrafine Grains ◽  
The Wire

AbstractThe rapid development of high-speed rail requires copper contact wire that simultaneously possesses excellent electrical conductivity, thermal stability and mechanical properties. Unfortunately, these are generally mutually exclusive properties. Here, we demonstrate directional optimization of microstructure and overcome the strength-conductivity tradeoff in copper wire. We use rotary swaging to prepare copper wire with a fiber texture and long ultrafine grains aligned along the wire axis. The wire exhibits a high electrical conductivity of 97% of the international annealed copper standard (IACS), a yield strength of over 450 MPa, high impact and wear resistances, and thermal stability of up to 573 K for 1 h. Subsequent annealing enhances the conductivity to 103 % of IACS while maintaining a yield strength above 380 MPa. The long grains provide a channel for free electrons, while the low-angle grain boundaries between ultrafine grains block dislocation slip and crack propagation, and lower the ability for boundary migration.

Investigating flexible textile-based coils for wireless charging wearable electronics

2019 ◽  
Vol 50 (3) ◽  
pp. 333-345 ◽  
Author(s):  
Danmei Sun ◽  
Meixuan Chen ◽  
Symon Podilchak ◽  
Apostolos Georgiadis ◽  
Qassim S Abdullahi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Electromagnetic Field ◽  
Electric Field ◽  
Dimensional Stability ◽  
Screen Printing ◽  
Wearable Electronics ◽  
Wireless Charging ◽  
The Magnetic Field ◽  
Screen Printed

Smart and interactive textiles have been attracted great attention in recent years. This research explored three different techniques and processes in developing textile-based conductive coils that are able to embed in a garment layer. Coils made through embroidery and screen printing have good dimensional stability, although the resistance of screen printed coil is too high due to the low conductivity of the print ink. Laser cut coil provided the best electrical conductivity; however, the disadvantage of this method is that it is very difficult to keep the completed coil to the predetermined shape and dimension. The tested results show that an electromagnetic field has been generated between the textile-based conductive coil and an external coil that is directly powered by electricity. The magnetic field and electric field worked simultaneously to complete the wireless charging process.

Intercomponent Momentum Transport and Electrical Conductivity of Collisionless Plasma

1973 ◽  
Vol 51 (24) ◽  
pp. 2604-2611 ◽  
Author(s):  
H. E. Wilhelm
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Collisionless Plasma ◽  
Electrical Current ◽  
Distribution Functions ◽  
Momentum Transport ◽  
Ion Drift ◽  
Moment Approximation ◽  
Electrons And Ions ◽  
Two Component

Based on the Lenard–Balescu equation, the interaction integral for the intercomponent momentum transfer in a two-component, collisionless plasma is evaluated in closed form. The distribution functions of the electrons and ions are represented in the form of nonisothermal, displaced Max wellians corresponding to the 5-moment approximation. As an application, the transport of electrical current in an electric field is discussed for infrasonic up to sonic electron–ion drift velocities.

scholarly journals Experimental study on variation law of electrical parameters and temperature rise effect of coal under DC electric field

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yunpeng Yang ◽  
Zhihui Wen ◽  
Leilei Si ◽  
Xiangyu Xu
Keyword(s):  
Electric Field ◽  
Temperature Rise ◽  
Experimental System ◽  
Gas Production ◽  
Breakdown Field ◽  
Coal Surface ◽  
Electrical Parameters ◽  
Slow Cooling ◽  
Microstructural Changes ◽  
Anthracite Coal

AbstractJoule heats which are generated by coals in an applied electric field are directly correlated with variation resistivity of electrical parameters of coals. Moreover, the joule heating effect is closely related with microstructural changes and relevant products of coal surface. In the present study, a self-developed applied direct current (DC) field was applied onto an experimental system of coals to investigate variation resistivity of electrical parameters of highly, moderately and lowly metamorphic coal samples. Moreover, breakdown voltages and breakdown field intensities of above three coal samples with different metamorphic grades were tested and calculated. Variation resistivity of electrical parameters of these three coal samples in 2 kV and 4 kV DC fields were analyzed. Results show that internal current of all coal samples increases continuously and tends to be stable gradually after reaching the “inflection point” at peak. The relationship between temperature rise effect on anthracite coal surface in an applied DC field and electrical parameters was discussed. The temperature rise process on anthracite coal surface is composed of three stages, namely, slowly warming, rapid warming and slow cooling to stabilize. The temperature rise effect on anthracite coal surface lags behind changes of currents which run through coal samples. There’s uneven temperature distribution on anthracite coal surface, which is attributed to the heterogeneity of coal samples. In the experiment, the highest temperature on anthracite coal surface 65.8 ℃ is far belower than the lowest temperature for pyrolysis-induced gas production of coals 200 ℃. This study lays foundations to study microstructural changes and relevant products on coal surface in an applied DC field.

Two-terminal vertical thyristor using Schottky contact emitter to improve thermal instability

Nano Futures ◽  
2021 ◽  
Author(s):  
Min-Won Kim ◽  
Ji-Hun Kim ◽  
Jun-Seong Park ◽  
Byoung-Seok Lee ◽  
Sangdong Yoo ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Work Function ◽  
Thermal Instability ◽  
Schottky Contact ◽  
Memory Cell ◽  
Cross Point ◽  
Operation Temperature ◽  
Metal Work Function ◽  
Metal Work ◽  
Contact Metal

Abstract In a two-terminal-electrode vertical thyristor, the latch-up and latch-down voltages are decreased when the memory operation temperature of the memory cells increases, resulting in a severe reliability issue (i.e., thermal instability). This study fundamentally solves the thermal instability of a vertical-thyristor by achieving a cross-point memory-cell array using a vertical-thyristor with a structure of vertical n++-emitter, p+-base, n+-base, and p++-emitter. The vertical-thyristor using a Schottky contact metal emitter instead of an n++-Si emitter significantly improves the thermal stability between 293 and 373 K. Particularly, the improvement degree of the thermal stability is increased significantly with the use of the Schottky contact metal work function. Because the thermal instability (i.e., degree of latch-up voltage decrement vs. memory operation temperature) decreases with an increase in the Schottky contact metal work function, the dependency of the forward current density between the Schottky contact metal and p+-Si based on the memory operation temperature reduces with increase in the Schottky contact metal work function. Consequently, a higher Schottky contact metal work function produces a higher degree of improvement in the thermal stability, i.e., W (4.50 eV), Ti (4.33 eV), Ta (4.25 eV), and Al (4.12 eV). Further research on the fabrication process of a Schottky contact metal emitter vertical-thyristor is essential for the fabrication of a 3-D cross-point memory-cell.

Electro-conductively deposited carbon fibers for power controllable heating elements

RSC Advances ◽  
2015 ◽  
Vol 5 (34) ◽  
pp. 26998-27002 ◽  
Author(s):  
Chang Hyo Kim ◽  
Moo Sung Kim ◽  
Yoong Ahm Kim ◽  
Kap Seung Yang ◽  
Seung Jo Baek ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Carbon Fibers ◽  
Industrial Applications ◽  
Excellent Thermal Stability

Carbon fibers are considered as one of the promising heating elements in various industrial applications because of their excellent thermal stability and electrical conductivity.

Relationship Between Thermal Stability and Summer Oxygen Depletion in a Prairie Pothole Lake

1980 ◽  
Vol 37 (9) ◽  
pp. 1433-1438 ◽  
Author(s):  
M. H. Papst ◽  
J. A. Mathias ◽  
J. Barica
Keyword(s):  
Thermal Stability ◽  
Air Temperature ◽  
Algal Biomass ◽  
Thermal Instability ◽  
Oxygen Depletion ◽  
Prairie Pothole ◽  
Night Time ◽  
Algae Blooms ◽  
Principal Factors ◽  
Prairie Lakes

Periods of summer oxygen depletion (summerkill), occurring in shallow prairie lakes, are dependent on the collapse of algae blooms but are not an obligatory result of the collapse. A period of thermal instability following this bloom collapse, or coincidental with it, is a necessary requirement. Wind stress and night-time air temperature are the principal factors determining the degree of thermal stability. These findings explain the speed with which oxygen depletion can occur, that the occurrence of algal biomass collapses without severe oxygen depletion (partial collapses), and the correlation between the occurrence of periods of lake oxygen depletion and changing weather conditions.Key words: lake, summerkill, anoxia, mixing, oxygen depletion, thermal stability, weather, Aphanizomenon

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