• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.481-484
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• 2003

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators have significant advantages over porcelain and glass insulators. With the gradual improvement of their design and material, their reliability has also increased. It is however difficult to establish how they will perform after several years of service. Aging of the insulator weathershed may lead to damages such as excessive chalking and crazing, erosion and tracking which affect the insulator performance. In service insulator are subjected to aging stresses such as humidity, pollution and electrical field which act singly or in combination. There have been numerous accelerated laboratory tests developed with the intention of evaluating suitability of polymeric materials. Some of these are strictly material tests, where as, others evaluate full scale devices. Service experience plays a key role in the utility selection of polymer insulator, but is time consuming, and may not always be available. Hence there is a need for a meaningful and reliable accelerated aging test for polymer insulator. This paper describes multi-stress aging test for reliability of polymer insulator This paper presents the rule of multi-stress aging test and test chamber for polymer insulator in korea electrotechnology research institute.

• Elastomers and Composites
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• 제50권4호
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• pp.292-296
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• 2015

Biomimetic artificial basilar membrane being a core part of artificial cochlear requires performance evaluation through aging test. To evaluate the aging properties of PVDF piezoelectric membrane used for artificial basilar membrane, its mechanical properties such as tensile strength and elastic modulus and piezoelectric property such as piezoelectric constant were measured. The aging test conditions and acceleration constants were calculated based on Arrhenius model. The changes in tensile strengths and elastic moduli measured were less than 10~20% after aging test equivalent for 10 years. The piezoelectric constants were decreased drastically to 80% of its initial value in the early stage of the aging test and expected to decrease slowly down to 65% over 10 years. The experimental results show the reliability of totally implantable novel artificial cochlear and will contribute its commercialization.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권2호
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• pp.62-67
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• 2002

This paper provides the results of accelerated aging test of 18kV ZnO lightning arresters to investigate the leakage current characteristics. It was impossible to establish the replacement criterion for field operating lightning arrester because conventional aging test was only focused on the aging of ZnO elements. In general, it is possible to replace the aged arresters before the failure in the field using the leakage current measurement because it must be increased by the aging. But we can not use the method because we don't know the characteristics of the installed lightning arresters. Therefore in this paper we applied operating voltage and accelerating cycle which consists of temperature and humidity to the arresters. Then we measured the variation of total and resistive leakage current and found out the characteristics of the acted lightning arresters.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.210-213
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• 2007

In this study accelerated aging test cycle and equipment was developed for aging test of polymer housed surge arresters under domestic weather condition In order to investigate aging characteristics of polymer surge arresters electrical and chemical analysis of the arresters which are used for accelerated aging test and outdoor exposure test were conducted. Through the analysis the capability of the proposed method was verified and characteristics data were presented for maintenance of domestic arresters. Based on these results long term reliability assessment method was proposed for polymer housed distribution surge arresters.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.480-483
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• 2002

This paper through shift norm of insulator and research by accident prevention countermeasure special skill authoritativeness verification of insulator and Long Term aging factor for power transmission analysis and evaluate and prove quality of insulator wish to. Assessment technique by aging of own porcelain insulator observes ageing factor for reciprocity comparison through several examinations. Through cool and heat accelerated Aging test, can measure the leakage current change amount that ensue to each Cycle. Can confirm own blazing fire factor as distribution freshness that ensue in HRB Test's hardness value.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1343-1344
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• 2006

There have been numerous accelerated aging laboratory tests for evaluating suitability of polymeric materials and devices. Aging test for materials and its full scale device has been conducted. Service experience plays a key role in the utility section of composite insulators. A meaningful and reliable accelerated aging test is needed for evaluating composite insulator. During the service these insulators are subjected to aging stress such as humidity, pollution, and electrical field, and erosion and tracking of the weathershed occurs. This paper presents the criteria of reliability evaluation and evaluation facilities for 22.9 kV suspension composite insulator. We adopt the criteria of reliability evaluation consist of two test methods. One is CEA tracking wheel test for examining the tracking and erosion performance of composite insulator. The other is multi-stress aging test for examining effects of environmental factors such as UV, temperature, humidity, etc on composite insulator.

• 열처리공학회지
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• 제7권4호
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• pp.270-276
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• 1994

The effects of thermomechanical and duplex aging treatment on precipitation behavior were investigated for the 8090 aluminium alloy by tensile test, hardness test, plane-strain fracture toughness test and electron microscope. Both pre-aging stretch and duplex aging with pre-aging stretch were effective to homogenize the distribution of S' phase in this alloys. The latter makes more homogeneous distribution of S' phase than that of the former, but the sizes of S' phase in both specimens are almost same. The size and distribution of 0' phase were not changed by thermomechanical or duplex aging treatment. The strength was increased by thermomechanical treatment, but the elongation was decreased. Duplex aging treatment couldn't change the strength and elongation. Pre-aging stretch and duplex aging with pre-aging stretch have same effect on the strength and elongation. The increase of strength by thermomechanical treatment in 8090 alumunium alloy was caused by homogeneously precipitated S' phase.

• Elastomers and Composites
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• 제54권4호
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• pp.351-358
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• 2019

To evaluate the aging of a rubber pad in power window switch which is the part of a vehicle, the accelerated thermal aging test of rubber pad material is performed. Finite element analysis was performed using the nonlinear material constants of the rubber pad to calculate the operating force, and the Arrhenius relationship was derived from the aging temperature and time. The aging test was performed at 150, 180, 210, or 240 ℃ for 1 to 60 days. When the operating force of the rubber pad is changed by 10% from the initial value, the service life is expected to be 113 years, which is much longer than the life of the vehicle. This indicates that the aging life of the rubber pad is sufficiently safe and the operating force of the rubber pad during the life of the vehicle (20 years) was decreased by approximately 8.4%. By examining the correlation between the shear elastic modulus and operating force calculated from finite element analysis under each aging test condition, the changes in the operating force of the rubber pad and the shear elastic modulus showed good linear relationship. The aging life could be predicted by the change in shear elastic modulus and a process for predicting the aging life of automotive power window switch rubber pad parts is described herein.

• Nuclear Engineering and Technology
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• 제36권5호
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• pp.475-484
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• 2004

Extending the lifetime of a nuclear power plant [(hereafter referred to simply as NPP)] is one of the most important concerns in the global nuclear industry. Cables are one of the long-life items that have not been considered for replacement during the design life of a NPP. To extend the cable life beyond the design life, it is first necessary to prove that the design life is too conservative compared with actual aging. Condition monitoring is useful means of evaluating the aging condition of cable. In order to simulate natural aging in a nuclear power plant. a study on accelerated aging must first be conducted. In this paper, evaluations of mechanical aging degradation for a neoprene cable jacket were performed after accelerated aging under tcontinuous and intermittent heating conditions. Contrary to general expectations, intermittent heating to the neoprene cable jacket showed low aging degradation, 50% break-elongation, and 60% indenter modulus, compared with continuous heating. With a plant maintenance period of 1 month after every 12 or 18 months operation, we can easily deduce that the life time of the cable jacket of neoprene can be extended much longer than extimated through the general EQ test. which adopts continuous accelerated aging for determining cable life. Therefore, a systematic approach that considers the actual environment conditions of the nuclear power plant is required for determining cable life.

• 전기학회논문지
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• 제59권10호
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• pp.1832-1838
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• 2010

Aging of transformer insulating material in natural ester insulating oil is compared to that in conventional transformer oil. Aging of insulating paper and insulating oil have been studied by performing accelerated thermal aging test. Sealed aging test vessels containing cooper, laminated core, Kraft paper and insulating oil(natural oil or mineral oil) were aged at $140^{\circ}C$ for 500, 1000, 1500 and 2000 hours. Insulating oils after aging are investigated with total acid number, breakdown voltage and viscosity. Also, degradation of insulating paper after aging is determined using breakdown voltage and mechanical strength. Accelerated aging studies demonstrate a slower aging rate for natural ester insulating oil compared to the rate for conventional mineral oil.