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(,10.1Type testing of cables and accessoriesBERUJN S.M., GRUNTJES R.J.B., ROELOfS G.P.T., Kema Nederland, Arnhem, The Netherlands

Résumé1

Parce que les câbles et leurs.accessoiresreprésentent une partie importante des réseauxélectriques, ils sont soumis à de nombreux essais,dont les essais de type. Pour ces essais plusieursnormes sont applicables. Les essais de type nesont pas superflus car il apparaît que 26% desmatériels essayés sont refusés suite à un défautde conception. Le taux de refus pour lesaccessoires (33%) est supérieur à celui des câbles(17%). Pour les accessoires, le VDE 278 est unenorme sévère; 50% des matériels sont refusés enessai. Il ne se dégage pas de tendance particulièresur le taux de refus, cependant le taux dedéfaillance en essai des accessoires tend àaugmenter.

Abstract

Because cables and accessories are an importantpart of the electric infrastructure they are subjectedta several tests. One of these tests are type tests.For type tests several standards are available. Typetesting of cables and accessories is not asuperfluous luxury, while it appears that around 26%of the abjects do not pass the type tests because ofdesign failures. The failure rate for accessories(33%) is higher than for cables (17%). Foraccessories, VDE 278 ls a severe standard, 50% ofthe objects does not pass type tests according ta thisstandard. No c1eartrend in failure rate can be seenover the years, although the failure rate ofaccessories has the tendency ta increase.

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Standards used for type testing of cables andaccessories

Figure 1 Number of type tests performed as.afunction of the standard

OtherVDE 278IEC502IEC 840

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At this moment there are several national andinternational standards for testing of MV and HVcables and accessories. The most appliedinternational standards can be divided into fourcategories, according ta the nominal voltage:

• 150 - 500 kV, IEC 60267 5 in preparation• 6 - 30 kV, e.g. IEC 60502-2 and -4 and VDE 278• 30 -150 kV, e.g. IEC 60840• 1 and 3 kV, e.g. IEC 60502-1

From the 166 type tests performed in six years time,most tests are performed according ta IEC 60840,IEC 60502 and VDE 278, as is shown in Figure 1.

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Introduction

Cables and accessories are an important part of theeiectric infrastructure. The necessity of a high qualityof manufacturing ls basically expected [1]. Becauseof this, cab les and accessories are subjected taseveral tests in several manufacturing stages. Onecan distinguish between for instance pre-qualificationtests, type tests, routine tests, acceptance tests andafter laying tests.

These tests can be performed according ta differentstandards, depending on the rated voltage of thecable or accessory and the requirements of thepurchaser, for instance VDE 278 [2], IEC 60502 [3],IEC 60840 [4], etc.

To prove the correct design of the cable andaccessories, type tests are often required. Themanufacturer and the utilities have to make choicesbetween several standards and they have ta decideif only the cable or accessories will be tested or thatthe combination that will be used 'will be tested.

ln this paper results will be presented of type testsperformed on cables and accessories during the lastsix years (1993-1998) at KEMA High-VoltageLaboratory. Figures are presented about the totalnumber of cables and accessories tested, accordingta which standard, the number of failures and causesof the failures. At the end of the paper someconclusions are drawn and sorne recommendationsare given.

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