Effect of Magnetic Fields on DC Interruption by Liquid Nitrogen in the HTS Electrical System

The high on-state loss of cryogenic solid-state circuit breakers makes it a heavy burden in realizing the High-Temperature Superconducting (HTS) electrical system. Due to the ability to work in cryogenic circumstances and extremely low on-state loss, the LN 2 switch shows excellent application poten...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2021-11, Vol.31 (8), p.1-4
Main Authors: Li, Hongxu, Xiang, Bin, Wang, Dongyu, Junaid, Muhammad, Geng, Yingsan, Liu, Zhiyuan, Wang, Jianhua, Tu, Youping
Format: Article
Language:English
Subjects:
Aircraft power systems
Circuit breakers
DC circuit breakers
DC power systems
Electric potential
High speed cameras
High temperature
High temperature superconducting
High-temperature superconductors
Liquid nitrogen
Magnetic field effects
Magnetic fields
Magnetic separation
Magnetism
Magnets
Neodymium
Superconducting magnets
Switches
Switching circuits
Voltage
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Summary:The high on-state loss of cryogenic solid-state circuit breakers makes it a heavy burden in realizing the High-Temperature Superconducting (HTS) electrical system. Due to the ability to work in cryogenic circumstances and extremely low on-state loss, the LN 2 switch shows excellent application potential in the HTS electrical system. However, the effect of the magnetic fields on the arcing process in the LN 2 is still unclear. This paper aims to obtain the effect of the magnetic fields on the arcing process in the LN 2 . Neodymium (NdFeB) magnets are used to provide the changeable magnetic fields. DC interruptions ranging from 200 A to 1800 A are conducted under 0 mT, 20 mT, and 50 mT respectively. A high-speed camera is also employed to capture the arcing process. Arcing in the LN 2 under magnetic fields is characterized as the arc dwell period and arc voltage rapidly increasing period, which is quite similar to that in the air, but more frequent arc restrikes are observed. The magnetic fields strengthen the convective arc cooling by mixing the arc with LN 2 and the vaporized N 2 , contributing to the sharp increase in arc voltage. Thus, the magnetic fields significantly increase the arc voltage and its raising rate. 630 V/1038 A is successfully interrupted under the magnetic field of 50 mT in the LN 2 . The successfully interrupted current increases by 8 times when magnetic fields are applied.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2021.3091050