Mechanism for impulse conversion of water trees to electrical trees in XLPE

Author

Boggs, Steven ; Densley, John ; Kuang, Jinbo

Author_Institution

Electr. Insulation Res. Center, Connecticut Univ., Storrs, CT, USA

Volume

13

Issue

2

fYear

1998

fDate

4/1/1998 12:00:00 AM

Firstpage

310

Lastpage

315

Abstract

A lightning impulse causes substantial capacitive current in a water tree channel which, as a result of its small cross section, has relatively low conductance. Transient, nonlinear finite element computations with coupled thermal and electric fields for the geometry of a 15 kV XLPE dielectric cable indicate that an 80 kV lightning impulse can cause the water within a water tree channel to boil over a range of four orders of magnitude in water conductivity, from 10^-2 S/m to 10² S/m. Boiling of the water in a water tree channel reduces substantially the yield stress of the XLPE, raises the pressure within the water tree channel, and is likely to leave a cavity which can support partial discharge resulting in electrical tree initiation

Keywords

XLPE insulation; electric admittance; finite element analysis; insulation testing; lightning; power cable insulation; trees (electrical); voids (solid); 15 kV; 80 kV; XLPE; XLPE dielectric cable; cavity; coupled thermal/electric fields; electrical trees; impulse conversion; lightning impulse; low conductance; partial discharge; substantial capacitive current; transient nonlinear finite element computations; water boiling; water tree channel; water trees; yield stress reduction; Dielectrics and electrical insulation; Insulation life; Lightning; Polymers; Stress; Surges; Thermal conductivity; Trees - insulation; Underwater tracking; Voltage;

fLanguage

English

Journal_Title

Power Delivery, IEEE Transactions on

Publisher

ieee

ISSN

0885-8977

Type

jour

DOI

10.1109/61.660895

Filename

660895