The shape of electrical trees formed in XLPE cable insulation at low temperature under AC and harmonic voltages are fibrillar type. Life of cable insulation failure due to electrical treeing was analysed through Weibull distribution studies. It is observed that the voltage wave shape and peak factor exhibit high influence on the life of cable insulation due to electrical treeing. Harmonics with higher THD's and the failure rate of cable insulation due to treeing are the same. The presence of 4th and 5th harmonics in supply voltage could cause early failure of cable insulation. Ultra High Frequency (UHF) signal radiated during tree growth process, under harmonic voltages lies in the range 0.5-1.5 GHz. Phase Resolved Partial Discharge (PRPD) analysis using spectrum analyser has revealed that under 50 Hz, discharges occur near zero crossing and in the presence of harmonics, it occurs when the rate of voltage rise is high. The discharge occurs at its peak under low frequency AC voltage of 1 Hz. © 2015 Elsevier Ltd. All rights reserved.

Ramanujam Sarathi

Department of Electrical Engineering

Kanikrishnan Sethupathi

Department Of Physics

Cables

Cryogenics

FAILURE ANALYSIS

Forestry

Harmonic analysis

Insulating materials

liquid nitrogen

Partial discharges

Polymers

Spectrum analyzers

TAPES

Weibull distribution

CRYOGENIC INSULATIONS

Cryogenic temperatures

ELECTRICAL TREEING

PHASE RESOLVED PARTIAL DISCHARGES

TREEING

Ultra-high frequency

XLPE

Insulation

Electrical engineering

nitrogen

Polyethylene

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Transactions on Electrical and Electronic Materials

Role of Micro and Nanofillers in Electrical Tree Initiation and Propagation in Cross-Linked Polyethylene Composites

In the present study, impact of high frequency ac voltage and harmonics in ac voltages on treeing were studied. When the applied voltage is high, a bush type tree forms irrespective of frequency of the supply voltage. Influence of harmonics on shape of tree formed indicates that a voltage wave with high total harmonic distortion have characteristics much similar to high frequency ac voltage. It is observed that the tree inception time is much lower with 11th harmonic ac voltages with higher THD. Presence of odd harmonics of equal magnitude, irrespective of amount of total harmonic distortion, the shape of the tree formed is almost same as the tree generated with 50 Hz ac voltage. The injected PD current pulses during treeing process have rise time of few nanoseconds. The UHF signals generated during tree growth (at the point of inception and propagation) have signal bandwidth in the range of 1-2 GHz. Measure of UHF signal magnitude during treeing process could help one to classify the shape of tree formed. Weibull distribution studies were carried out to estimate the life of XLPE cable insulation failure due to electrical treeing under different harmonic ac voltages. Independent higher order harmonic ac voltages with increase in total harmonic distortion reduce the life of cable insulation due to electrical treeing. © 2012 IEEE.

IEEE Transactions on Dielectrics and Electrical Insulation

Understanding electrical treeing phenomena in XLPE cable insulation under harmonic AC voltages adopting UHF technique

Analysis on heat loss characteristics of a 10kV HTS power substation

2013 IEEE International Conference on Solid Dielectrics (ICSD)

Electrical treeing from needle implants in XLPE during very low frequency (VLF) voltage testing

The application of the cryogenic system on the HTS power cable circuit in actual grid

Investigating the impact of harmonics on the breakdown of epoxy resin through electrical tree growth

Electrical treeing in XLPE cable insulation at cryogenic temperature under harmonic AC voltages

Journal	Data powered by TypesetCryogenics
Publisher	Data powered by TypesetElsevier Ltd
ISSN	00112275
Open Access	No