Electrical and mechanical properties of the oil-paper insulation under stress of the hot spot temperature

Han, Seungsu; Li, Qingmin; Li, Chengrong; Yan, Jiangyan

doi:10.1109/tdei.2013.003967

Cited by 26 publications

(18 citation statements)

References 17 publications

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“…Impact test was carried out using standard Izod (cantilever type) and standard Charpy (simply supported) specimens and evaluation of impact on specimen in as-cast condition and heat-treated condition. It is absorbed on heat treatment, the impact values will come down appreciably [5][6].…”

Section: Impact Studiesmentioning

confidence: 99%

“…Commonly, austempering heat treatment is carried out on ductile iron; hence the name "Austempered Ductile Iron" or "ADI". ADI has found its application in a wide range of components [5,6] for many engineering sectors as in gears, crank shafts, transmissions, suspensions, earth-moving and construction equipment, railways etc. Wear is an important property, which is evaluated in materials to find out its response to undergo loss of material.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Analysis of Mechanical Properties, Wear and Corrosion Characteristics of IS400/12 Grade Ductile Iron Casting

Agrawal,

Kumar

2019

IJEAT

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In the present research investigation, ductile iron castings conforming to IS400/12 grade casting were produced using green sand moulds. The castings were produced in a regular production foundry using 1.25T Induction Furnace. The molten metal was subjected to standard desulphurisation and modularisation to get graphite in the nodular form. The molten metal was poured into the sand mould and allowed to solidify. test was held for different loads viz. 300 gm, 400 gm and 500 gm and different speeds conditions viz. 950 r.p.m, 1430 r.p.m and 2130 r.p.m Based on the earlier investigation by the above group the castings were austenitised at 900 o C for 120minutes and quenched in a salt bath consisting of potassium nitrate and sodium nitrate in the ratio of 55:45 and maintained at 310 o C for 120 minutes to bring about austempering treatment. The result in austempered ductile iron will consist of graphite nodules in a matrix of bainite[1,2]. The effect of austempering heat treatment on microstructure, mechanical properties and wear characteristics were studied and compared with the ascast condition. Mechanical properties such as ultimate tensile strength, percentage elongation, hardness and impact strength were determined. Wear tests were carried out to determine the weight loss of specimens; using pin on disc type machine. Wear . The results of the research investigation indicate that the heat treated castings shows higher Ultimate Tensile Setength values (35.93% increase), elongation values (24.2% increase) and Brinell hardness values (12.05% increases) as compared to the as-cast condition of casting. From the dry sliding wear studies, it is seen that heat treated specimensshows higher resistance to wear compared to the ascast specimens.

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Section: Impact Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Analysis of Mechanical Properties, Wear and Corrosion Characteristics of IS400/12 Grade Ductile Iron Casting

Agrawal,

Kumar

2019

IJEAT

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“…However, a more concrete model of aging can be designed when all degradation processes are fully understood. Certain degradation factors acting in a concrete EIS can be identified, such as electric field intensity [10][11][12][13], temperature [14][15][16][17], mechanical stress [18], radiation [19], moisture [20], dust [21], chemical stress [22], etc. and including these degradation mechanisms into a single model would be impossible.…”

Section: Introductionmentioning

confidence: 99%

Proposal of Physical-Statistical Model of Thermal Aging Respecting Threshold Value

Soucek¹,

Trnka

Hornak

2017

Energies

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Abstract:The aging of electrical insulation material or a system is a main issue for designers of high-voltage (HV) machines. Precise determination of the life cycle of electrical insulation is one way of improving the efficiency of electrical machines involved in the production and transmission of electrical energy. Much effort has been devoted to preparing statistical or physical methods of Electrical Insulating System (EIS) life time estimation in the real operation of electrical machinery. The main aim of this paper is to introduce a new physical-statistical model of thermal aging respecting the threshold value. This model is based on thermal aging model and the main difference between this model and previously published models is taking into account the threshold value of degradation factor. The complete design of this model is presented in this paper, including functions defining the threshold value of the effect of the degradation factor depending on the temperature. Proposed model was verified by accelerated thermal aging test at selected temperatures (160, 170, 180 • C) and time intervals (0, 120, 240 h) on a commonly used transformer board. The breakdown voltage was set as an indicating parameter of the level of thermal aging and was measured according to standard IEC 60243-1. Collected data from these measurements were used for threshold value determination (431.23 K) and verification of proposed physical-statistical model of thermal aging respecting the threshold value.

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“…So far, there has been a lot of research about cooling improvement in power transformers using mineral oil [21][22][23][24]. The reason is that hottest spot temperature inside windings of the oilimmersed power transformers is one of the main manifestations of the thermal stress which leads to aging and decomposition of both liquid and solid insulation material (oil and cellulose) more rapidly as compared with less heated spots [25][26][27]. Although some studies have examined the aging of dielectric paper submerged in mineral and vegetable oil [6,28], all of them have taken into account that both liquids have the same cooling capacity.…”

Section: Introductionmentioning

confidence: 99%

Thermal degradation assessment of Kraft paper in power transformers insulated with natural esters

Fernández

Delgado

Fernández

et al. 2016

Applied Thermal Engineering

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Electrical and mechanical properties of the oil-paper insulation under stress of the hot spot temperature

Cited by 26 publications

References 17 publications

Experimental Analysis of Mechanical Properties, Wear and Corrosion Characteristics of IS400/12 Grade Ductile Iron Casting

Experimental Analysis of Mechanical Properties, Wear and Corrosion Characteristics of IS400/12 Grade Ductile Iron Casting

Proposal of Physical-Statistical Model of Thermal Aging Respecting Threshold Value

Thermal degradation assessment of Kraft paper in power transformers insulated with natural esters

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