Post-arc current measurement and interruption performance of vacuum interrupter in DC interruption

2021 ◽  
Author(s):  
Qiang Tang ◽  
Shenli Jia ◽  
Zongqian Shi ◽  
Yongpeng Mo
Keyword(s):  
Plasma Density ◽  
Failure Modes ◽  
Circuit Breakers ◽  
Transient Model ◽  
Vacuum Interrupter ◽  
Memory Time ◽  
Promising Solution ◽  
Arc Current ◽  
The Common ◽  
Current Zero

Abstract In the DC grid, fault current rises very fast due to low impedance. Fast DC circuit breakers are needed to isolate faults and avoid a collapse of the common DC grid voltage. Based on the forced current zero (CZ) technology, the vacuum interrupter (VI) equipped with fast electromagnetic repulsion mechanism is a very promising solution of fast DC interruption. The experimental research on the DC interruption characteristics of a VI, namely by examining the post‑arc current (PAC) is presented in this paper. The dependence of the interruption capability on the PAC is analysed. What’s more, the failure modes of the VI under various experiment conditions are summarized. A former finding was that not all the arcing history which starts from the electrodes separating to the CZ has influence on the PAC but only a very short duration of several microseconds right before the CZ takes effects. New experiment results are added in this paper to support the former finding. Another former finding was that a longer electrode separation will bring about higher PAC. In this paper, both the influence of the arcing memory time and the electrodes separation are owed to a higher residual plasma density, which is verified by a model for calculating the residual plasma density and the continuous transient model (CTM) for calculating PAC.

Methodology for Analysis of Schottky Diode Failures

2010 ◽  
Author(s):  
Bhanu P. Sood ◽  
Michael Pecht ◽  
John Miker ◽  
Tom Wanek
Keyword(s):  
Failure Mode ◽  
Schottky Diode ◽  
Failure Modes ◽  
Schottky Diodes ◽  
Failure Mechanisms ◽  
Forward Voltage ◽  
Fast Switching ◽  
Voltage Drops ◽  
The Common

Abstract Schottky diodes are semiconductor switching devices with low forward voltage drops and very fast switching speeds. This paper provides an overview of the common failure modes in Schottky diodes and corresponding failure mechanisms associated with each failure mode. Results of material level evaluation on diodes and packages as well as manufacturing and assembly processes are analyzed to identify a set of possible failure sites with associated failure modes, mechanisms, and causes. A case study is then presented to illustrate the application of a systematic FMMEA methodology to the analysis of a specific failure in a Schottky diode package.

Impact of 750kV Transmission Line Series Compensation Capacity on Power Frequency Overvoltage

2014 ◽  
Vol 986-987 ◽  
pp. 330-333
Author(s):  
Ding Jun Wen ◽  
Xiu Bin Zhang ◽  
Hong Gang Chen ◽  
Feng Jiang ◽  
Ya Ming Sun
Keyword(s):  
Transmission Line ◽  
Single Phase ◽  
Power Transmission ◽  
Series Compensation ◽  
Two Phase ◽  
Transient Model ◽  
Power Frequency ◽  
Arc Current ◽  
Recovery Voltage ◽  
Insulation Coordination

The overvoltage calculation of 750kV transmission line with series compensation has great significance on the design, insulation coordination and protection of the line. In this paper, a transient model of 750kV power transmission system with series compensation is established. Effects of different capacity on no-load capacitive rise overvoltage, single-phase grounding overvoltage, two-phase grounding overvoltage are calculated. Secondary arc current and recovery voltage of different series compensation capacity in single-phase grounding is also calculated.

Measurement of Transient Temperature Distribution at Anode Surface After Current Zero in Vacuum Interrupter

2021 ◽  
Vol 141 (11) ◽  
pp. 712-717
Author(s):  
Akira Daibo ◽  
Yoshimitsu Niwa ◽  
Naoki Asari ◽  
Wataru Sakaguchi ◽  
Yo Sasaki ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Anode Surface ◽  
Transient Temperature ◽  
Vacuum Interrupter ◽  
Transient Temperature Distribution ◽  
Current Zero

scholarly journals Post-Arc Characteristics of High-Current Arcs in Vacuum Circuit-Breakers

2019 ◽  
Vol 6 (2) ◽  
pp. 170-174
Author(s):  
N. Wenzel ◽  
W. Haas
Keyword(s):  
Short Circuit ◽  
Early Period ◽  
Metal Vapor ◽  
Transverse Magnetic ◽  
High Current ◽  
Electric Resistance ◽  
Circuit Breakers ◽  
Arc Characteristics ◽  
Current Zero ◽  
Short Circuit Currents

The post-arc (PA) characteristics of vacuum arcs in transverse magnetic field contacts are studied for short-circuit currents of up to 123 kA peak and transient recovery voltages below 875 V. The measured PA currents are interpreted in terms of an Electric Resistance Model and the models of Andrews-Varey, Langmuir-Child, and Slepian-Schmelzle. Whereas in the late PA period, the calculations do not agree well with the measurements, the PA behavior is well described in the early period after current-zero. It is concluded that the PA discharge is amplified by ionization of metal vapor particles in the boundary sheath due to electron impact.

scholarly journals Additive-Free Formic Acid Dehydrogenation Catalyzed by a Cobalt Complex

2020 ◽  
Author(s):  
Nicolas Lentz ◽  
Alicia Aloisi ◽  
Pierre Thuéry ◽  
Emmanuel Nicolas ◽  
Thibault Cantat
Keyword(s):  
Formic Acid ◽  
Cobalt Complex ◽  
Intermediate Formation ◽  
Mechanistic Study ◽  
Catalytic Dehydrogenation ◽  
Turnover Number ◽  
Promising Solution ◽  
The Common ◽  
Safe Transport ◽  
Formic Acid Dehydrogenation

The reversible storage of hydrogen through the intermediate formation of Formic Acid (FA) is a promising solution to its safe transport and distribution. However, the common necessity of using bases or additives in the catalytic dehydrogenation of FA is a limitation. In this context, two new cobalt complexes (<b>1</b> and <b>2</b>) were synthesized with a pincer PP(NH)P ligand containing a phosphoramine moiety. Their reaction with an excess FA yields a cobalt(I)-hydride complex (<b>3</b>). We report here the unprecedented catalytic activity of <b>3</b> in the dehydrogenation of FA, with a turnover frequency (TOF) of 4000 h<sup>-1</sup> and a turnover number (TON) of 454, without the need for bases or additives. A mechanistic study reveals that the ligand has a non-innocent behaviour due to intermolecular hydrogen bonding, which is influenced by the concentration of formic acid

Investigation on the current-zero characteristic of vacuum circuit breakers

Vacuum ◽  
2016 ◽  
Vol 134 ◽  
pp. 63-68 ◽  
Author(s):  
Guowei Ge ◽  
Minfu Liao ◽  
Xiongying Duan ◽  
Zhihui Huang ◽  
Jinqiang Huang ◽  
...  
Keyword(s):  
Circuit Breakers ◽  
Zero Characteristic ◽  
Current Zero
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