TY - JOUR
T1 - Optical observations of partial discharge-induced bubbles generated in subcooled liquid nitrogen at atmospheric pressure
AU - Suehiro, Junya
AU - Imasaka, Kiminobu
AU - Hara, Masanori
N1 - Funding Information:
The authors thank Mr. Yasunori Matsumoto and Mr. Hiroshi Imakiire for their help in experimental works. This research was partly supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science.
PY - 2008/6
Y1 - 2008/6
N2 - Composite insulation system of liquid nitrogen and solid insulator, which are widely employed in high 4TC superconducting equipment, can be deteriorated by partial discharge (PD) generated in highly stressed region. By subcooling the liquid nitrogen below the boiling point of 77 K at atmospheric pressure, the superconducting power device can obtain higher performance because the critical current density of the superconductor can be increased. The subcooled liquid nitrogen may also have better properties as electrical insulation medium than pool boiling one because gaseous bubble generation is suppressed. In this study, effects of subcooling temperature on PD characteristics were investigated at atmospheric pressure. Behavior of PD induced bubbles was optically investigated using a high speed digital imaging system as well as a laser light scattering method. These optical observations were synchronized with PD signal detection in order to clarify relationship between the PD intensity and bubble behavior. It was found that PD induced bubbles were strongly influenced by the PD energy as well as temperature of the subcooled liquid nitrogen.
AB - Composite insulation system of liquid nitrogen and solid insulator, which are widely employed in high 4TC superconducting equipment, can be deteriorated by partial discharge (PD) generated in highly stressed region. By subcooling the liquid nitrogen below the boiling point of 77 K at atmospheric pressure, the superconducting power device can obtain higher performance because the critical current density of the superconductor can be increased. The subcooled liquid nitrogen may also have better properties as electrical insulation medium than pool boiling one because gaseous bubble generation is suppressed. In this study, effects of subcooling temperature on PD characteristics were investigated at atmospheric pressure. Behavior of PD induced bubbles was optically investigated using a high speed digital imaging system as well as a laser light scattering method. These optical observations were synchronized with PD signal detection in order to clarify relationship between the PD intensity and bubble behavior. It was found that PD induced bubbles were strongly influenced by the PD energy as well as temperature of the subcooled liquid nitrogen.
UR - http://www.scopus.com/inward/record.url?scp=45849099829&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=45849099829&partnerID=8YFLogxK
U2 - 10.1109/TDEI.2008.4543097
DO - 10.1109/TDEI.2008.4543097
M3 - Article
AN - SCOPUS:45849099829
SN - 1070-9878
VL - 15
SP - 620
EP - 625
JO - IEEE Transactions on Dielectrics and Electrical Insulation
JF - IEEE Transactions on Dielectrics and Electrical Insulation
IS - 3
M1 - 4543097
ER -