Breakdown mechanism of liquid nitrogen viewed from area and volume effects

Author

Hayakawa, N. ; Sakakibara, H. ; Goshima, H. ; Hikita, M. ; Okubo, H.

Author_Institution

Nagoya Univ., Japan

Volume

4

Issue

1

fYear

1997

fDate

2/1/1997 12:00:00 AM

Firstpage

127

Lastpage

134

Abstract

We investigated the area and volume effects on the breakdown strength in liquid nitrogen (LN₂) to discuss the breakdown mechanism in cryogenic liquids for superconducting power apparatus. We measured breakdown voltages in LN₂ with and without thermal bubbles over a very wide range of the electrode size. Experimental results revealed that the breakdown mechanism changed from an area dominant to volume effective region at larger electrode configurations in LN₂. Moreover, we discussed the contribution rate of area and volume effects to the breakdown strength in LN₂. It was suggested that a mutual contribution of area and volume effects appeared in breakdown characteristics in LN₂ under thermal bubble conditions, as a phenomenon peculiar to cryogenic liquids. Consequently, we pointed out that it is very important to consider both thermal bubbles and electrode surface condition for HV insulation of superconducting power apparatus

Keywords

dielectric liquids; electric breakdown; electric strength; insulation testing; machine insulation; machine testing; nitrogen; superconducting machines; HV insulation; N₂; area effects; breakdown mechanism; breakdown strength; breakdown voltages; cryogenic liquids; electrode configurations; electrode size; electrode surface condition; liquid N₂; superconducting power apparatus insulation; thermal bubbles; volume effects; Cryogenics; Electric breakdown; Electrodes; Liquids; Nitrogen; Ocean temperature; Rough surfaces; Sea surface; Superconducting transmission lines; Surface roughness;

fLanguage

English

Journal_Title

Dielectrics and Electrical Insulation, IEEE Transactions on

Publisher

ieee

ISSN

1070-9878

Type

jour

DOI

10.1109/94.590883

Filename

590883