Distribution Transformer Life Assessment with Ambient Temperature Rise Projections

Sathyanarayana, B. R.; Heydt, G.T.; Dyer, M.

doi:10.1080/15325000902918875

Cited by 19 publications

(7 citation statements)

References 7 publications

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“…where ξ is the lifetime, A and B are constants that depend on the material and T is the absolute temperature. A related rule of thumb often used by designers, known as the 'ten degree' rule, states that beyond the rated temperature the insulation ages twice as fast for every 10 • C rise in temperature [33].…”

Section: Introductionmentioning

confidence: 99%

Thermal Degradation Phenomena of Polymer Film on Magnet Wire for Electromagnetic Coils

Kavanagh

Gyftakis

McCulloch

2021

IEEE Trans. on Ind. Applicat.

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Polymer film insulation degradation is a major problem for electric machines which leads to short circuits, overheating and eventually the occurrence of catastrophic failure. Electrical insulation materials provide the vital function of turn-to-turn, phase to phase, and phase-to-ground electrical isolation for the electromagnetic coils and windings. This paper investigates the characterisation of early-onset degradation of thin-film magnet wire insulation at elevated temperatures from 200 to 275 • C. Sample specimens were analysed after ageing for 100 hours in terms of their physical properties [surface roughness, mass], chemical properties [Fourier Transform Infra-Red (FTIR) spectroscopy], dielectric properties [capacitance and dissipation factor] and electrical properties [voltage breakdown strength and resistance]. The results show that the specimen roughness and mass increase and decrease uniformly, respectively, with increased ageing temperature. Similar degradation results trends with respect to ageing temperature for the dielectric properties and electrical insulation strength is documented. The paper also reports an extended ageing study which investigates early breakdown voltage (EBV) on sample specimens over a much longer time duration, that of up to 1600 hours.

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Section: Introductionmentioning

confidence: 99%

Thermal Degradation Phenomena of Polymer Film on Magnet Wire for Electromagnetic Coils

Kavanagh

Gyftakis

McCulloch

2021

IEEE Trans. on Ind. Applicat.

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“…Due to the difficulty in real-time detection of hot spot temperature in transfer, the calculation methods are often used to predict the hot spot locations in transformer, including the lumped parameter method and numerical method. For the lumped parameter method, such as thermoelectricity analogy [4,5] and temperature rise guidelines [6,7], the detailed information for oil flow and temperature distributions for different components in transformer cannot be obtained, and the prediction accuracy would be questionable. For numerical method, although it is time-consuming, the detailed information of local oil flow and temperature distributions in transformer can be captured, and the results should be more reliable.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Electromagnetic Loss and Heat Transfer in an Oil-Immersed Transformer

et al. 2020

Mathematical Problems in Engineering

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Transformer is one of the most important pieces of equipment in power system. The insulation aging and lifespan of transformer are significantly affected by hot spot distributions of internal components inside. In the present paper, the electromagnetic losses of different components and heat transfer process in a three-phase forced oil circulation transformer (400 kVA-15 kV/400 V) are numerically studied with finite element method. The leakage magnetic flux and eddy current loss density for metal components and oil tank are carefully analyzed, and the effect of metal components’ electromagnetic loss on hot spot temperature of different components and oil flow in transformer is also studied. It is found that the surface current of metal components is generated by leakage magnetic flux, and surface current density is large when leakage magnetic flux concentrates. The effect caused by relative magnetic permeability of metal components is remarkable on electromagnetic loss of metal components and oil tank, while the effect caused by relative magnetic permeability of transformer tank is relatively small. Due to the mixing of metal components on oil flow, the heat transfer of core is enhanced, its hot spot temperature is lowered, and the hot spot locations of coil and core also change. These results are meaningful for further understanding of heat transfer process in transformer and important for the optimal design of transformer.

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“…For an assumed 4°C rise in ambient temperature during 1900–2100, the predicted loss of life in the interval from 1990 to 2045 rises approximately 32% at a relatively warm location and 8% at a relatively cold location. Reference [5] applied an improved model of top oil temperature rise differing from the IEEE C57.91 model to assess the impact of ambient temperature change on transformer life, based on seven transformers and four loading test beds specified in IEEE C57.115. With the assumption of temperature rise of 3.5°C in 100 years, a probabilistic model for ambient temperature rise was performed to conclude that a reduction in the life of a transformer was about 3–6 years for the case studied, and there was a marked difference in the mean life of a transformer for several different loading conditions.…”

Section: Introductionmentioning

confidence: 99%

Analyzing the Impact of Ambient Temperature Indicators on Transformer Life in Different Regions of Chinese Mainland

Bai

Gao

Liu³

2013

The Scientific World Journal

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Regression analysis is applied to quantitatively analyze the impact of different ambient temperature characteristics on the transformer life at different locations of Chinese mainland. 200 typical locations in Chinese mainland are selected for the study. They are specially divided into six regions so that the subsequent analysis can be done in a regional context. For each region, the local historical ambient temperature and load data are provided as inputs variables of the life consumption model in IEEE Std. C57.91-1995 to estimate the transformer life at every location. Five ambient temperature indicators related to the transformer life are involved into the partial least squares regression to describe their impact on the transformer life. According to a contribution measurement criterion of partial least squares regression, three indicators are conclusively found to be the most important factors influencing the transformer life, and an explicit expression is provided to describe the relationship between the indicators and the transformer life for every region. The analysis result is applicable to the area where the temperature characteristics are similar to Chinese mainland, and the expressions obtained can be applied to the other locations that are not included in this paper if these three indicators are known.

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Distribution Transformer Life Assessment with Ambient Temperature Rise Projections

Cited by 19 publications

References 7 publications

Thermal Degradation Phenomena of Polymer Film on Magnet Wire for Electromagnetic Coils

Thermal Degradation Phenomena of Polymer Film on Magnet Wire for Electromagnetic Coils

Numerical Study of Electromagnetic Loss and Heat Transfer in an Oil-Immersed Transformer

Analyzing the Impact of Ambient Temperature Indicators on Transformer Life in Different Regions of Chinese Mainland

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