Diagnosis: Articulations and Short Circuits

Protecting inverter-interfaced microgrids is challenging as conventional time-overcurrent protection becomes unusable due to the lack of fault current. There is a great need for novel protective relaying methods that enable the application of protection coordination on microgrids, thereby allowing for microgrids with larger areas and numbers of loads while not compromising reliable power delivery. Tools for modeling and analyzing such microgrids under fault conditions are necessary in order to help design such protective relaying and operate microgrids in a configuration that can be protected, though there is currently a lack of tools applicable to inverter-interfaced microgrids. This paper introduces the concept of applying an optimization problem formulation to the topic of inverter-interfaced microgrid fault modeling, and discusses how it can be employed both for simulating short-circuits and as a set of constraints for optimal microgrid operation to ensure protective device coordination.

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Identification of Electrical Fire Melted Marks of Copper Wires by Electron Backscattered Diffraction (EBSD)

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.513-517.281 ◽

2014 ◽

Vol 513-517 ◽

pp. 281-285

Author(s):

Cheng Sun ◽

Min Ju Ding ◽

Yong Feng Zhang ◽

Xun Tan ◽

Peng Wang ◽

...

Keyword(s):

Copper Wire ◽

Short Circuit ◽

Testing Methods ◽

Electron Backscattered Diffraction ◽

Qualitative And Quantitative ◽

Metallographic Method ◽

Short Circuits ◽

In Fire ◽

Misorientation Of Grains ◽

Electrical Apparatus

A variety of electrical apparatus used in daily life can cause fires because of internal or external factors. During cause identification of an electrical fire, the first short circuit melted marks of copper wire have been considered highly important because they are direct proofs. Additionally, overloaded short circuit caused by the overload of current due to excessive electrical usage can give rise to an electrical fire. Despite extensive research on the first short circuit in fire scenes, the overloaded short circuit remains difficult to be distinguished because of the limitation of commonly used testing methods. Conventional metallographic method is intuitionistic and simple, but may not provide detailed data of crystals such as misorientation of grains. Here a new method (electron backscattered diffraction, EBSD) is applied for identification of the first and overloaded short-circuited melted marks of copper wires in electrical fire scenes. Results show obvious morphological distinctions in melted marks of copper wires between the first and overloaded short circuits. Qualitative and Quantitative differences obtained from the contrast of the above two short circuit situations may assist for cause identification of electrical fires in the future.

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Realizing poly(ethylene oxide) as a polymer for solid electrolytes in high voltage lithium batteries via simple modification of the cell setup

Materials Advances ◽

10.1039/d1ma00009h ◽

2021 ◽

Author(s):

Lukas Stolz ◽

Gerrit Homann ◽

Martin Winter ◽

Johannes Kasnatscheew

Keyword(s):

Ethylene Oxide ◽

High Voltage ◽

Lithium Batteries ◽

Polymer Electrolytes ◽

Solid Electrolytes ◽

Simple Modification ◽

Poly Ethylene Oxide ◽

Benchmark System ◽

Short Circuits ◽

Poly Ethylene

Cell failure of polymer electrolytes is rather the result of short circuits instead of assumed electrolyte oxidation. A spacer with a constant and defined distance can avoid this failure, thus realize a benchmark system for a more systematic R&D.

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Sodium Solid Electrolytes: NaxAlOy Bilayer-System Based on Macroporous Bulk Material and Dense Thin-Film

Materials ◽

10.3390/ma14040854 ◽

2021 ◽

Vol 14 (4) ◽

pp. 854

Author(s):

Antonia Hoppe ◽

Cornelius Dirksen ◽

Karl Skadell ◽

Michael Stelter ◽

Matthias Schulz ◽

...

Keyword(s):

Pore Size ◽

Bulk Material ◽

Sol Gel ◽

Dense Layer ◽

X Ray Diffraction ◽

Bilayer System ◽

Step Procedure ◽

Short Circuits ◽

Α Al2o3 ◽

Sol Gel Synthesis

A new preparation concept of a partially porous solid-state bilayer electrolyte (BE) for high-temperature sodium-ion batteries has been developed. The porous layer provides mechanical strength and is infiltrated with liquid and highly conductive NaAlCl4 salt, while the dense layer prevents short circuits. Both layers consist, at least partially, of Na-β-alumina. The BEs are synthesized by a three-step procedure, including a sol-gel synthesis, the preparation of porous, calcined bulk material, and spin coating to deposit a dense layer. A detailed study is carried out to investigate the effect of polyethylene oxide (PEO) concentration on pore size and crystallization of the bulk material. The microstructure and crystallographic composition are verified for all steps via mercury intrusion, X-ray diffraction, and scanning electron microscopy. The porous bulk material exhibits an unprecedented open porosity for a NaxAlOy bilayer-system of ≤57% with a pore size of ≈200–300 nm and pore volume of ≤0.3 cm3∙g−1. It contains high shares of crystalline α-Al2O3 and Na-β-alumina. The BEs are characterized by impedance spectroscopy, which proved an increase of ionic conductivity with increasing porosity and increasing Na-β-alumina phase content in the bulk material. Ion conductivity of up to 0.10 S∙cm−1 at 300 °C is achieved.

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