A short method of estimating lifetime of polypropylene film using step-stress tests

Laghari, J.R.; Cygan, P.J.; Khechen, W.

doi:10.1109/14.64506

Cited by 33 publications

(12 citation statements)

References 7 publications

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“…Since the voltage procedure of protocol 1 is the same as that of [2], and that of protocol 2 is the same as that of [7], the data is also analysed by their methods. The ageing parameters obtained by the different methods are listed in Table 4 It can be seen that the ageing parameters obtained by the new method are quite close to each other, while the ageing parameters obtained by the other two methods have a greater difference.…”

Section: Protocol 1: Constant Voltage Stepmentioning

confidence: 99%

“…The material is usually designed to withstand the voltage stress for decades of years. In order to obtain the reliability of the design, accelerated life tests are usually taken under constant higher voltage stress based on the empirical model: the inverse power low (t L ·V n = constant) and the exponential low (c·exp(-k·V)=constant) [2].However, there still is not a unified standard for testing high voltage DC extruded cable systems, only a recommendation. Furthermore the recommendation only gives a lower limit of ageing parameter (n=10 in the inverse power law), which directly determines the voltage used in the test [3].…”

Section: Introductionmentioning

confidence: 99%

“…However the maximum likelihood method is still difficult to solve. W. Khachen and J. R. Laghari [2] gave a simple method to estimate the parameters from stepstress tests data. This method treated the total time of applied stress and the voltage as separate Weibull distributions, but this method ignores the step application and brings many errors.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A new method of estimating the inverse power law ageing parameter of XLPE based on step-stress tests

Liu

et al. 2013

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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In recent years, HVDC cables have been greatly improved, 500kV XLPE DC cable has been developed, and many XLPE DC cables of lower applied voltage have been used in HVDC systems. However, there still is not a unified standard for testing high voltage DC extruded cable systems, only a recommendation. Furthermore the recommendation only gives a lower limit of ageing parameter (n=10 in the inverse power law t L ·V n = constant), which directly determines the voltage used in the test. A more precise value of ageing parameter is needed in order to improve the testing method. The most common method of estimating the ageing parameter uses constant-stress tests at different voltages (fields) and is based on the inverse power model, but this method takes a lot of time and cannot give usable data when the applied voltage is low. An alternative method is to use step-stress tests based on the cumulative life model. This approach can give usable data quickly, but parameter evaluation is much harder than for the constant-stress tests and the approximations necessary for the data solution unavoidably brings errors. In this paper, a new method of estimating the ageing parameter of XLPE is proposed.Step-stress tests are also used but a new parameter evaluation method is presented, which avoids complicated approximations in the data solution. This new method can greatly reduce the errors and easily give the ageing parameter. A series of step-stress tests on 0.3 mm thick XLPE samples have been carried out to illustrate the method. The values of the ageing parameter, n, obtained from different methods are compared, and it is found that the new method gives a greater consistency between different test protocols, indicating a more accurate estimation of its value. However, a comparison between the new method and the constant stress accelerated life tests is still needed to confirm the accuracy of the new method.

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Section: Protocol 1: Constant Voltage Stepmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A new method of estimating the inverse power law ageing parameter of XLPE based on step-stress tests

Liu

et al. 2013

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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“…Performances of partial discharges in oilpaper insulation and dissolved gases in insulating oils under pulsating DC voltages were introduced in [14]. Time to breakdown and lifetime models of oil-immersed insulation systems for HVDC converter transformers were presented in [15,16]. However, there are very few published works on the electrical breakdown properties and lifetime models of oilpaper insulation under combined voltage stresses and at various temperatures.…”

Section: Introductionmentioning

confidence: 98%

Electrical aging lifetime model of oil-impregnated paper under pulsating DC voltage influenced by temperature

Grzybowski

2013

IEEE Trans. Dielect. Electr. Insul.

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Main insulation of windings connected with valves in high voltage direct current (HVDC)convert transformers withstands pulsating DC voltages. This paper presents breakdown properties of oil-impregnated paper under pulsating DC voltages at different temperatures. Progressive stress tests were carried out to obtain breakdown voltages of oil-impregnated paper with thickness of 0.2 mm under pulsating DC voltages at different temperatures. Constant stress tests were executed to measure time to breakdown of the oil-paper specimens. Both types of the experiments were also undertaken under either AC or DC voltages. An electrical aging lifetime model was proposed for the oil-impregnated paper, and parameters of the electrical aging lifetime model were presented. Experiments and analysis results show that the breakdown voltages and time to breakdown of oilpaper insulation are influenced by temperature significantly.

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“…The step-up voltage application method is used to acquire sufficient measurement data efficiently. This method is capable of damaging the oil-paper insulation in the same extent compared with the constant voltage application method [19][20][21].…”

Section: Voltage Application Methodsmentioning

confidence: 99%

Partial Discharge of Needle-Plane Defect in Oil-Paper Insulation under AC and DC Combined Voltages: Developing Processes and Characteristics

Sun

Zhu

et al. 2017

Energies

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Partial discharge (PD) behaviors of oil-paper insulation is distinctive in AC and DC combined electric fields in converter transformers from PD behaviors in pure AC or DC electric fields. The present study focuses on the PD developing processes and characteristics of oil-paper insulation systems with needle-plane defects under different AC/DC proportions. The degradation of oil-paper insulation can be accelerated by PD pulses incurred by needle-plane defects. AC-DC combined voltages are applied to the needle-plane defect model simultaneously in the established experimental platform, and the proportions of AC/DC voltages are decided according to the cases in actual converter transformers. The developing processes from the initiation of partial discharge until final breakdown were observed for each AC/DC proportion. PD parameters and patterns were acquired by a detector using the pulse current method. The test results indicate that the inception and breakdown voltages increase with the increase of the DC component in AC-DC combined voltages. However, pulse repetition rate and amplitude of PD shows a descending trend when AC/DC proportion decreases. Meanwhile, the PD recurrence rate in the phase between 180 • and 360 • becomes higher than that in the phase between 0 • and 180 • at the initial stage as the DC proportion increases; high-amplitude discharges mainly occur in the phase range between 180 • and 360 • when the pressboard is close to breakdown. The current study is useful in further research on fault diagnosis in converter transformers.

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A short method of estimating lifetime of polypropylene film using step-stress tests

Cited by 33 publications

References 7 publications

A new method of estimating the inverse power law ageing parameter of XLPE based on step-stress tests

A new method of estimating the inverse power law ageing parameter of XLPE based on step-stress tests

Electrical aging lifetime model of oil-impregnated paper under pulsating DC voltage influenced by temperature

Partial Discharge of Needle-Plane Defect in Oil-Paper Insulation under AC and DC Combined Voltages: Developing Processes and Characteristics

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