Electrical insulation characteristics of liquid helium under high speed rotating field

Author

Ishii, I. ; Fuchino, S. ; Okano, Hl ; Tamada, N.

Author_Institution

Electrotech. Lab., Ibaraki, Japan

Volume

32

Issue

4

fYear

1996

fDate

7/1/1996 12:00:00 AM

Firstpage

2284

Lastpage

2287

Abstract

Electrical breakdown behavior of liquid helium was investigated under high speed rotating field. In the development of superconducting turbine generators, it is essential to obtain knowledge of the electrical insulation characteristics of liquid helium under high speed rotating field. When the current of the field magnet of a superconducting generator is changed, changing magnetic field generates heat in the conductor and causes bubbles in the liquid helium around the conductor. The behavior of these bubbles is affected largely by the buoyancy which is generated by the centrifugal force. Electrical breakdown behavior of the liquid helium is strongly dependent on the gas bubbles in the liquid. The electrical breakdown voltage between electrodes was measured in a rotating cryostat with and without heater input for bubble formation. Reduction of the breakdown voltage by the heater power was smaller in a rotating field than that in a nonrotating field

Keywords

bubbles; electric breakdown; insulation testing; liquid helium; machine insulation; machine testing; superconducting machines; superconducting magnets; turbogenerators; breakdown voltage; bubble formation; buoyancy; electrical breakdown behavior; field magnet current; high speed rotating field; insulation characteristics; liquid helium; rotating cryostat; superconducting turbine generators; Character generation; Conductors; Dielectric liquids; Dielectrics and electrical insulation; Electric breakdown; Helium; Magnetic fields; Magnetic liquids; Superconducting magnets; Turbines;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.508622

Filename

508622