The Impact of Shunt Capacitor Installations on Power Circuit Breaker Application

T. McCauley; D. Pelfrey; W. Roettger; C. Wood

doi:10.1109/tpas.1980.319783

The Impact of Shunt Capacitor Installations on Power Circuit Breaker Application

IEEE Transactions on Power Apparatus and Systems ◽

10.1109/tpas.1980.319783 ◽

1980 ◽

Vol PAS-99 (6) ◽

pp. 2210-2222 ◽

Cited By ~ 12

Author(s):

T. McCauley ◽

D. Pelfrey ◽

W. Roettger ◽

C. Wood

Keyword(s):

Circuit Breaker ◽

Power Circuit ◽

Shunt Capacitor ◽

The Impact

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Capacitor Commutation Method for MVDC Hybrid Circuit Breakers

Designs ◽

10.3390/designs5020028 ◽

2021 ◽

Vol 5 (2) ◽

pp. 28

Author(s):

Hyosung Kim

Keyword(s):

Short Circuit ◽

Circuit Breaker ◽

Reverse Current ◽

Resonant Circuit ◽

Power Circuit ◽

Power Sources ◽

Semiconductor Switch ◽

Current Commutation ◽

Dc Circuit Breaker ◽

Hybrid Circuit

The medium voltage DC (MVDC) type system can connect multiple terminals to a common MVDC bus, so it is possible to connect several renewable DC power sources to the common MVDC bus, but a DC circuit breaker is needed to isolate short circuit accidents that may occur in the MVDC bus. For this purpose, the concept of a hybrid DC circuit breaker that takes advantage of a low conduction loss contact type switch and an arcless-breaking semiconductor switch has been proposed. During break the hybrid switch, a dedicated current commutation device is required to temporarily bypass the load current flowing through the main switch into a semiconductor switch branch. Existing current commutation methods include a proactive method and a reverse current injection method by a LC (Inductor-capacitor) resonant circuit. This paper proposes a power circuit of a new MVDC hybrid circuit breaker using a low withstanding voltage capacitor branch for commutation and a sequence controller according to it, and verifies its operation through an experiment.

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A descriptive analysis of the impact of COVID-19 on Emergency Department attendance and visit characteristics in Singapore

10.21203/rs.3.rs-149642/v2 ◽

2021 ◽

Author(s):

Mei Qiu Lim ◽

Fahad Javaid Siddiqui ◽

Seyed Ehsan Saffari ◽

Andrew Fu Wah Ho ◽

Johannes Nathaniel Min Hui Liew ◽

...

Keyword(s):

Emergency Department ◽

Severe Disease ◽

Descriptive Analysis ◽

Circuit Breaker ◽

Historical Period ◽

Management Planning ◽

Crowd Management ◽

Patient Demographics ◽

Icd 10 ◽

The Impact

Abstract Background: The coronavirus disease 2019 (COVID-19) has impacted the utilisation of Emergency Department (ED) services worldwide. This study aims to describe the changes in attendance of a single ED and corresponding patient visit characteristics before and during the COVID-19 period. Methods: In a single-centre retrospective cohort study, we used descriptive statistics to compare ED attendance, patient demographics and visit characteristics during the COVID-19 period (1 January – 28 June 2020) and its corresponding historical period in 2019 (2 January – 30 June 2019). Results: Mean ED attendance decreased from 342 visits/day in the pre-COVID-19 period, to 297 visits/day in the COVID-19 period. This was accompanied by a decline in presentations in nearly every ICD-10-CM diagnosis category except for respiratory-related diseases. Notably, we observed reductions in visits by critically ill patients and severe disease presentations during the COVID-19 period. We also noted a shift in ED patient case-mix from ‘Non-fever’ cases to ‘Fever’ cases, likely giving rise to two distinct trough-to-peak visit patterns during the pre-Circuit Breaker and Circuit Breaker period. Conclusions: This descriptive study revealed distinct ED visit trends across different time periods. The COVID-19 pandemic caused a reduction in ED attendances amongst patients with low-acuity conditions and those with highest priority for emergency care. This raises concern about treatment-seeking delays and possible impact on health outcomes. The downward trend in low-acuity presentations also presents learning opportunities for ED crowd management planning in a post-COVID-19 era.

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Analyzing the Impacts of Wind Generator on the Optimal Coordination of Overcurrent Relays

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.516-517.1316 ◽

2012 ◽

Vol 516-517 ◽

pp. 1316-1321

Author(s):

Ming Ta Yang ◽

Jin Lung Guan ◽

Jhy Cherng Gu

Keyword(s):

Distribution Systems ◽

Short Circuit ◽

Circuit Breaker ◽

Original System ◽

Wind Generator ◽

Linear Programming Methods ◽

Protection Strategies ◽

Overcurrent Relays ◽

Optimal Coordination ◽

The Impact

Wind generator and distribution systems after interconnection would change the short circuit fault characteristics of the original system and may lead to protection relay malfunctions, and review of the protection coordination. It is necessary to research the impact of existing protection strategies for distribution systems after wind generator interconnection. Linear programming methods were adopted for this study to review the coordination problems among feeder circuit breaker, lateral circuit breaker, and power fuse after radial distribution systems and wind generator interconnections.

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