Research of Dielectric spectroscopy on insulation ageing assessment of XLPE cables

Liu, Ji; Xu, You; Wei, Xindong; Li, Xiujing

doi:10.1109/ceidp.2013.6747454

Cited by 10 publications

(5 citation statements)

References 11 publications

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“…The de-polymerization and oxidation byproducts consequent to thermal ageing can increase the permittivity [21][22][23]. It can be more significant at higher frequencies such as 2.5 kHz as used for PDIV measurement and even higher under very fast steep-fronted square waveform excitation due to the non-negligible spectral energy of the voltage waveform.…”

Section: A Capacitance and Dissipation Factor As A Function Of Therma...mentioning

confidence: 99%

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A Contribution to Thermal Ageing Assessment of Glass Fibre Insulated Wire Based on Partial Discharges Activity

2022

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This paper aims to evaluate a Type-II insulated wire (i.e., Glass fibre insulated wire) as a function of thermal ageing time based on partial discharges (PD) activity. Partial discharge inception voltage (PDIV), partial discharge extinction voltage (PDEV), and repetitive partial discharge inception voltage (RPDIV) measurements have been performed on both unaged and thermally aged specimens. Each specimen modelled the turn-to-turn insulation; hence it was made by a pair of Glass fibre wires wrapped in PTFE tape for a mechanical purpose. The PD tests have been carried out under positive and negative unipolar square waveform excitations using different rise times: 80, 400 and 800 ns. The trend of PD quantities vs exposure time demonstrates that the effect of space charge accumulation under unipolar excitation must be taken into account when unaged and thermally aged specimens are compared. Results revealed that although sometimes thermally aged samples might show a temporary superiority in the short run, unaged ones always present a better performance after space charge accumulation, as expected. Following the statistic postprocessing of the collected data, shape/slope parameters of the Weibull distribution relevant to PDIV can be used as an ageing indicator for Glass fibre insulated wire. Finally, the permittivity evaluation vs thermal and electrical stresses have been performed, relying on the measured capacitance of each specimen just after every PD test. Such analysis revealed that thermal ageing increases permittivity in the long run. However, electrical stress has different impacts on permittivity depending on the rise time, polarity, and magnitude of the applied voltage.

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Section: A Capacitance and Dissipation Factor As A Function Of Therma...mentioning

confidence: 99%

“…Indeed, two factors can impact permittivity: thermal ageing and surface charge density caused by electrical stress with a steep-fronted waveform. The former can increase the permittivity in the long run [21][22][23] (Fig. 5).…”

Section: B Pdiv Analysis In Terms Of Thermal Ageing Rise Time and Pol...mentioning

confidence: 99%

A Contribution to Thermal Ageing Assessment of Glass Fibre Insulated Wire Based on Partial Discharges Activity

2022

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“…It is believed that long-chain XLPE molecules break into short chains and thermal motion becomes intense during the aging process, which can result in more polar groups and carriers. These changes lead to more interfacial polarization (Maxwell–Wagner–Sillars), and make the dielectric relaxation phenomenon more obvious [ 33 , 34 ].…”

Section: Resultsmentioning

confidence: 99%

Structural Changes and Very-Low-Frequency Nonlinear Dielectric Response of XLPE Cable Insulation under Thermal Aging

et al. 2023

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The structural changes and very-low-frequency (VLF) nonlinear dielectric responses are measured to evaluate the aging state of cross-linked polyethylene (XLPE) in power cables under various thermal aging conditions. For this purpose, the accelerated thermal aging experiments were performed on XLPE insulation materials at 90 °C, 120 °C and 150 °C with different durations of 240 h, 480 h and 720 h, respectively. The Fourier transform infrared spectrum (FTIR) characterization and differential scanning calorimeter (DSC) were tested to analyze the influence of different aging on physicochemical properties of XLPE insulation. Besides, the VLF dielectric spectra show that the permittivity and dielectric loss change significantly in the VLF range from 1 mHz to 0.2 Hz. A voltage–current (U–I) hysteresis curve referring to a standard sinusoidal voltage and the response current were introduced to characterize the nonlinear dielectric properties of XLPE insulation caused by thermal aging.

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“…On the other hand, it has been reported that the IC of a dielectric material can increase under thermal ageing phenomenon due to the depolymerization and oxidation byproducts. This can increase the permittivity of dielectric material and hence can contribute to increase capacitance [19][20][21]. Depolymerization is the process by which a polymer breaks down into smaller molecules.…”

Section: A Tanδ and Icmentioning

confidence: 99%

Life Characterization of PEEK and Nanofilled Enamel Insulated Wires Under Thermal Ageing

Khowja,

Vakil,

Ahmad

et al. 2024

IEEE Access

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This paper characterizes and develops life models for two different wire insulating materials: Poly-ether-ketone and nanofilled enamel (Allotherm wire). The article focuses on predicting the lifespan of PEEK and Allotherm wire insulation materials, targeting low voltage electrical machines. The study investigates the effects of thermal ageing on factors such as dissipation factor, insulation capacitance, and partial discharge inception voltage (PDIV). Delamination of the insulation coating is observed in both wires during the ageing process, resulting in an increase in the differential dissipation factor and insulation capacitance. With respect to its unaged condition, Allotherm wire exhibits faster degradation, showing 2.4and 4.5-times higher changes in the differential dissipation factor and insulation capacitance respectively compared to PEEK wire after the 16 th ageing cycle. In addition, Allotherm wire experiences faster deterioration of the PDIV, with a 42% reduction compared to 32% in PEEK after the same ageing cycle. Using a single-stress Arrhenius life model, the study estimates the relative thermal index (RTI) for both materials as 245°C for PEEK and 226.25°C for Allotherm wire. These results indicate a 72.1% decrease in the lifetime of PEEK and a 25.5% decrease in the lifetime of Allotherm wire when compared to the manufacturer's RTI specification.INDEX TERMS Dissipation factor, insulation capacitance, low voltage electrical machines, partial discharge inception voltage, thermal life, thermal index, thermal ageing, Time-to-Breakdown

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Research of Dielectric spectroscopy on insulation ageing assessment of XLPE cables

Cited by 10 publications

References 11 publications

A Contribution to Thermal Ageing Assessment of Glass Fibre Insulated Wire Based on Partial Discharges Activity

A Contribution to Thermal Ageing Assessment of Glass Fibre Insulated Wire Based on Partial Discharges Activity

Structural Changes and Very-Low-Frequency Nonlinear Dielectric Response of XLPE Cable Insulation under Thermal Aging

Life Characterization of PEEK and Nanofilled Enamel Insulated Wires Under Thermal Ageing

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