Space-charge and conduction-current measurements for the evaluation of aging of insulating materials for DC applications

Montanari, Gian Carlo; Fabiani, Davide; Bencivenni, L.; Garros, B.; Audry, C.

doi:10.1109/ceidp.1999.804587

Cited by 18 publications

(4 citation statements)

References 11 publications

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“…Replacing P Δ V by E h in eqn 1 gives the critical field For example, the results of Montanari and co‐workers yield a Δ V value of 10 −24 m 3 at 22 °C; therefore F c should be 15 kV mm −1 , which is in excellent agreement with the experimental field range of 13–18 kV mm −1 . Interestingly enough, the F c value deduced from morphological properties and electrical ageing of XLPE is in very good agreement with the so‐called threshold field of 18 kV mm −1 determined from polarization measurements by Montanari et al 11…”

Section: The Ageing Modelsupporting

confidence: 86%

Influence of high electrical fields on ageing and polarization properties of polyethylene

Crine

2002

Polymer International

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The influence of high electrical fields (above 20 kV mm−1) on ageing, polarization and morphology of polyethylene (PE) is discussed. Infrared and positron annihilation spectroscopy measurements together with capacitance measurements tend to indicate that polymer morphology is modified by high fields. We show that accelerated electrical ageing characteristics of PE are directly linked to morphology changes induced by the field. Below a so‐called critical field, the activation volume of the ageing process is dependent on field‐induced strain. Above the critical field, the amorphous phase is significantly deformed and weak van der Waals bonds are broken, leading to another faster ageing regime. There is excellent agreement between the proposed model and experimental data obtained with PE‐insulated high voltage cables. The possible relation between the submicrocavity formation proposed in our ageing model and various polarization measurements is discussed. It is our contention that strong charge injection occurs only after submicrocavity formation, ie after weak bonds are broken. As is well known, polarization currents obtained under high fields are controlled by space charges. It seems that wave packets and the negative resistance observed above 100 kV mm−1 in PE are associated with a steady state in field‐induced defect formation. This suggests that space charges are related to the formation of submicrocavities and, therefore, are a consequence and not a cause of high field ageing. © 2002 Society of Chemical Industry

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Section: The Ageing Modelsupporting

confidence: 86%

Influence of high electrical fields on ageing and polarization properties of polyethylene

Crine

2002

Polymer International

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“…It has been suggested that space charge built up in high voltage (HV) cable insulation is either the cause [1] of material degradation or a consequence of it [2], with subsequent electrical tree formation eventually leading to catastrophic failure of the insulation. Many studies [3][4][5][6][7] as well as an EU-sponsored programme called ARTEMIS [8] have shown that quantities that can be extracted from space charge measurement are sensitive to polymeric material changes due to electrical, thermal or electro-thermal stressing [9]. Studies of space charge behaviour on cable peelings have shown to be sensitive to prior cable stressing [10] and/or further endurance stressing [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

The effect of dc poling duration on space charge relaxation in virgin XLPE cable peelings

Tzimas

Rowland

Dissado

et al. 2010

J. Phys. D: Appl. Phys.

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The effect of DC poling time upon the time-dependent decay of space charge in insulation peelings of Cross-linked Polyethylene (XLPE) cable that had not previously experienced either electrical or thermal stressing is investigated. Two DC poling durations were used, two hours and twenty six hours at an electric field of 50kV/mm and at ambient temperature. Space charge was measured in the two samples investigated both during space charge accumulation and throughout its subsequent decay. The results show that the length of DC poling plays an important role in the subsequent decay. Despite the fact that both samples have had the same amount of space charge by the end of both short and long poling durations the time dependence of the space charge decay is different. Most of the charge stored in the sample that had experienced the short time poling decays rapidly after voltage removal. On the other hand the charge that is stored in the sample with the long DC poling duration decays slowly and its decay occurs in two stages. The data, which is analysed by means of the detrapping theory of space charge decay, implies that the charge stored in the material has occupied energy states with different trap depth ranges. The two poling durations lead to different relative amounts of charge in each of the two trap depth ranges. Possible reasons for this are discussed. Voltage on Volt off SC-2min Volt off SC-14min

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“…Space charge profile for specimens unaged (but thermally pre-treated) and aged at 20 kV/mm for 1000 h. The poling field and time were 70 kV/mm and 10000 s [34] It has been suggested that space charges can modify the microstructure of the polymer by enlarging the microcavities. This observation is supported by the results of small angle x-ray scattering (SAXS), where it was observed that the 20nm diameter of microcavities increased by 6% after 500 hours of dc electrical stress of 45kV/mm [35]. …”

Section: Laser Intensity Modulation Methods (Limm) and Pulsed Electroacosupporting

confidence: 78%

Space charge and electrical ageing of polymers in humid conditions

Das-Gupta

Proceedings of 2001 International Symposium on Electrical Insulating Materials (ISEIM 2001). 2001 Asian Conference on Electrica

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Space charges appear to play an unfavourable role by providing electrical charge transport in insulating polymers. Dielectric studies, particularly in the low frequency range < 1 0-3 Hz, thermally stimulated discharge current (TSDC), thermal transient current (TTC) and spatial distribution of space charges in the polymer bulk can provide useful information on the electrical health of insulating polymers, mostly in a non-destructive manner.

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Space-charge and conduction-current measurements for the evaluation of aging of insulating materials for DC applications

Cited by 18 publications

References 11 publications

Influence of high electrical fields on ageing and polarization properties of polyethylene

Influence of high electrical fields on ageing and polarization properties of polyethylene

The effect of dc poling duration on space charge relaxation in virgin XLPE cable peelings

Space charge and electrical ageing of polymers in humid conditions

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