Effect of the applied voltage frequency on the water tree shape in polyethylene

Maeda, T.; Kaneko, Daisaku; Ohki, Yoshimichi; Konishi, Teruko; Nakamichi, Yoshinobu; Okashita, M.

doi:10.1109/icsd.2004.1350344

Cited by 9 publications

(9 citation statements)

References 3 publications

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“…Figure 27 shows that the length of water trees grown in the lab whatever the type of cell essentially depends on the number of field cycles, that is on fatigue, in w x agreement with Ohki et al 93 . Note that Figure 27 shows all published results obtained with NaCl as the ionic solution.…”

Section: A More Realistic Modelsupporting

confidence: 78%

On the interpretation of some electrical aging and relaxation phenomena in solid dielectrics

Crine¹

2005

IEEE Trans. Dielect. Electr. Insul.

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Electrical aging and relaxation in solid dielectrics are phenomena studied for decades but still largely poorly understood. The lack of understanding, or sometimes the misunderstanding, are partly due to inadequate or deficient theories and partly due to wrong interpretation of theories or concepts developed for other materials than dielectrics. In addition, a serious analysis of some of the empirical and approximate relationships often used to interpret polymer relaxations reveals that they are not only limited and restrictive but also that they are based on very dubious assumptions. Dry or wet electrical aging is much more complex and often includes many phenomena with synergetic effects such as thermal aging, electrochemical reactions, space charge effects, etc. In this lecture, we intend to show that some of the theories often cited in the literature are wrong or inappropriate. We show why they cannot describe the phenomena at play and we present some alternatives for future work in the domains of relaxation and electrical aging.( ) The relations between aging, space charges and polarization of polyethylene PE ( ) under the influence of high electrical fields above 20 kVr r r r rmm are discussed in light of our electrical aging model. It is our contention that strong charge injection occurs only after nanocavity formation, i.e. above the critical field. The amorphous phase is then significantly deformed and weak van der Waals attraction bonds are broken, leading to another faster aging regime. The possible relation between the nanocavity formation at moderate fields and bonds breaking at higher fields proposed in our aging model and various polarization measurements is discussed. One objective of this paper is to encourage the development of more complex and complete theories specific to dielectrics. Some experimental work needed to achieve this goal is pointed out.

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Section: A More Realistic Modelsupporting

confidence: 78%

On the interpretation of some electrical aging and relaxation phenomena in solid dielectrics

Crine¹

2005

IEEE Trans. Dielect. Electr. Insul.

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“…In general, smaller samples have higher breakdown strength and a smaller activation volume for aging (i.e. longer life at a given field) [2,5]. The common explanation is that smaller samples have statistically less defects or impurities and, as a result, they should be able to sustain a higher field.…”

Section: Frequency Influencementioning

confidence: 95%

“…We have already shown elsewhere that fatigue induced by the alternating field is a major source of polymer electrical aging [1,2,5]. However, fatigue, which is related to the number of field cycles, cannot explain all the differences observed between samples aged under various frequencies.…”

Section: Introductionmentioning

confidence: 91%

“…However, fatigue, which is related to the number of field cycles, cannot explain all the differences observed between samples aged under various frequencies. A good example is the water treeing results of Maeda et al obtained under various (and superposed) frequencies [5]. We intend to show in this paper that the alternating stress has two different-and significant-effects on the aging process compared to a DC stress.…”

Section: Introductionmentioning

confidence: 93%

“…Among other examples, it is well known that water trees grow much more rapidly under high frequency (500-3000 Hz) than under 50 Hz and almost no trees are found under dc fields [4,5]. The electrical breakdown field is also frequency dependent with higher values under DC than under AC power frequency [2,6].…”

Section: Introductionmentioning

confidence: 95%

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Cable life predictions from breakdown and accelerated aging tests: influence of frequency and high fields

Crine¹

2009

2009 IEEE Electrical Insulation Conference

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We have shown elsewhere that our model of dry electrical aging of extruded cables describes very well accelerated aging of XLPE cables performed at constant temperature and frequency. The model, without any adjustable constant, is based on two basic parameters: the activation energy and volume. The main objective of this paper is to show that frequency and high fields affect significantly the value of the activation volume. The influence of these aging parameters on the impulse and AC breakdown fields of actual XLPE cables are discussed. From a practical point of view, this means that the aging characteristics at constant temperature and frequency of a given cable might be predicted from fast breakdown tests performed under at least three different voltage raise ramps.

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AC and DC Electrical Aging of Polyethylene

Crine¹

2008

2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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Effect of the applied voltage frequency on the water tree shape in polyethylene

Cited by 9 publications

References 3 publications

On the interpretation of some electrical aging and relaxation phenomena in solid dielectrics

On the interpretation of some electrical aging and relaxation phenomena in solid dielectrics

Cable life predictions from breakdown and accelerated aging tests: influence of frequency and high fields

AC and DC Electrical Aging of Polyethylene

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