1997 Fiscal Year Final Research Report Summary
Mechanisms of dielectric breakdown of ljquid coolants under quench condition and estimation of withstand voltage
| Project/Area Number |
08455136
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
電力工学・電気機器工学
|
|---|
| Research Institution | KYUSHU UNIVERSITY |
|---|
Principal Investigator |
HARA Masanori Kyushu University, Graduate School of Information Science and Electrical Engineering, Professor, 大学院・システム情報科学研究科, 教授 (30039127)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
IMASAKA Kiminobu Kyushu University, Graduate School of Information Science and Electrical Enginee, 大学院・システム情報科学研究科, 助手 (40264072)
SUEHIRO Junya Kyushu University, Graduate School of Information Science and Electrical Enginee, 大学院・システム情報科学研究科, 助教授 (70206382)
|
|---|
| Project Period (FY) |
1996 – 1997
|
| Keywords | Superconducting Magnet / Quench / Insulation Design / Liquid Coolant / Thermal Bubble / Gradient force / Area Effect / Pool-boiling He-cooled |
|---|
| Research Abstract |
In this study, establishment of electrical insulation technique and development of insulation trust of a superconducting magnet were aimed at. Boiling phenomena of liquid nitrogen and helium used for coolant of the magnet under high electric field was investigated. Moreover, mechanism of breakdown of those liquid coolant and characteristics of withstand voltage were discussed. Obtained results were summarized as follows.
1.Electrical insulation design of pool-boiling He-cooled superconducting coils
Insulation design procedure was proposed and applied to a small SMES.It was found that the main parameters determining insulation space were delay time of quench protection switch, initial coil current, coil inductance, and conductor geometry and size.
2.Bubble behavior in liquid coolant under quench condition
Bubble behavior under high electric fields was studied theoretically and experimentally. The results showed that bubble motion was influenced mainly by an electrical gradient force acting on it. Then it is very important to pay attention to a setting of the gasp length in order to get a passage of the coolant under quench condition.
3.Breakdown characteristics of LNi and LHe including a superfluid condition were investigated statistically.
It was shown that the statistical characteristic of breakdown were well fitted to Weibull distribution based on weak-link theory and area effect was dominant rather than volume effect for size effect of electrodes to the breakdown characteristics.
|
