Title :
Electrical treeing in XLPE cable insulation under harmonic AC voltages
Author :
Sarathi, R. ; Oza, K.H. ; Pavan Kumar, C.L.G. ; Tanaka, T.
Author_Institution :
Dept. of Electr. Eng., IIT Madras, Chennai, India
fDate :
12/1/2015 12:00:00 AM
Abstract :
The shape of electrical trees gets altered due to applied voltage profile. Bush type electrical trees forms under harmonic voltages with lower THDs. With increase in harmonic level with increased THDs fibrillar type electrical trees were formed. Weibull distribution studies indicate that increase in harmonic level (odd/even) with higher THDs accelerates the tree growth in cable insulation causing early failure of cable insulation. The frequency content of the Ultra High Frequency (UHF) signals radiated due to tree formation lies in the frequency band of 0.5-2 GHz. Adoption of spectral power ratios to UHF signal can classify the shape of electrical trees that has incepted and propagating in the insulating material under different voltages. Phase Resolved Partial Discharge (PRPD) analysis using UHF signal indicates that discharges occurs under harmonic voltages where the rate of rise of voltage is high thereby accelerating the tree growth. During tree growth discharges occur in the entire phase of the triangular voltage. Partial discharges occur at the peak with the low frequency AC voltage and at the raising portion when the supply voltage is increased.
Keywords :
Weibull distribution; failure analysis; harmonic distortion; insulating materials; partial discharges; power cable insulation; trees (electrical); AC voltage harmonic; Weibull distribution; XLPE cable insulation electrical tree growth discharge; cable insulation early failure; frequency 0.5 GHz to 2 GHz; insulating material; lower THD fibrillar; phase resolved partial discharge analysis; ultra high frequency signal; Harmonic analysis; Needles; Power cable insulation; Power cables; Power system harmonics; Shape; Treeing; UHF signal; Weibull analysis; XLPE cables; power spectral analysis; voltage harmonics;
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on
DOI :
10.1109/TDEI.2015.005022