TY - JOUR

T1 - Study of Oil/Pressboard Creeping Discharges under Divergent AC Voltage - Part III

T2 - Effects of Temperature and Stress Type

AU - Zhou, Xin

AU - Werle, Peter

AU - Gockenbach, Ernst

AU - Imani, Mohammad Taghi

PY - 2022/1/31

Y1 - 2022/1/31

N2 - The present article studies the effects of temperature and stress type on the oil/pressboard creeping discharge under divergent ac voltages. A ramp-stress test determines the short-time electric strengths of the oil/pressboard interface. Subsequently, long-term tests are carried out at different temperatures using constant and step stresses, respectively. Afterward, a novel methodology is proposed to detect the developing fault using synchronous partial discharge (PD) and online dielectric measurements. The interface short-time electric strengths correlate positively with the temperature. In long-term tests, the creeping discharges can generate three failure modes to oil/pressboard insulation: interface flashover (FO), surface tracking (ST), and internal treeing (IT). Different failure modes vary significantly in the discharge characteristics and the severities of damage to the pressboard. Temperature plays an important role in determining the failure modes of creeping discharge, and its influence mechanism is expounded in terms of the change of material properties, the interface of electric and dielectric phenomena, and their sophisticated interplays. The influence of stress type is related to the cumulative effect of stressing and the voltage rising steepness. The proposed methodology proves to be a potent tool in detecting the developing IT.

AB - The present article studies the effects of temperature and stress type on the oil/pressboard creeping discharge under divergent ac voltages. A ramp-stress test determines the short-time electric strengths of the oil/pressboard interface. Subsequently, long-term tests are carried out at different temperatures using constant and step stresses, respectively. Afterward, a novel methodology is proposed to detect the developing fault using synchronous partial discharge (PD) and online dielectric measurements. The interface short-time electric strengths correlate positively with the temperature. In long-term tests, the creeping discharges can generate three failure modes to oil/pressboard insulation: interface flashover (FO), surface tracking (ST), and internal treeing (IT). Different failure modes vary significantly in the discharge characteristics and the severities of damage to the pressboard. Temperature plays an important role in determining the failure modes of creeping discharge, and its influence mechanism is expounded in terms of the change of material properties, the interface of electric and dielectric phenomena, and their sophisticated interplays. The influence of stress type is related to the cumulative effect of stressing and the voltage rising steepness. The proposed methodology proves to be a potent tool in detecting the developing IT.

KW - Dielectric breakdown

KW - electrothermal effects

KW - interface phenomena

KW - partial discharges (PDs)

KW - surface discharges

KW - tracking

UR - http://www.scopus.com/inward/record.url?scp=85124235645&partnerID=8YFLogxK

U2 - 10.1109/TDEI.2022.3146432

DO - 10.1109/TDEI.2022.3146432

M3 - Article

AN - SCOPUS:85124235645

VL - 29

SP - 119

EP - 126

JO - IEEE Transactions on Dielectrics and Electrical Insulation

JF - IEEE Transactions on Dielectrics and Electrical Insulation

SN - 1070-9878

IS - 1

ER -