Chainflex cables

Example 3: tested,tested, tested! “Millionsof double strokes”in an energy chainProfibus cables in permanentlymovingindustrial useFor users, it is hard to get an overview of the cable market.Competition between cable suppliers is intensifying and manufacturersare outshining one another in their promises to“guarantee service life for cables used in energy chains”.Catalogues claim ten million - or even as many as 50 million- double strokes when it comes to the service life of cablesused in applications involving movement.On taking a closer look at figures claimed, one must ask howtesting was done, or how realistic tests carried out actuallywere (for example length of travel, test radii, etc.) in order tobe able to provide such a guarantee.Even information stating that cables are tested in accordancewith VDE (Association of German electrical engineers) 0472,Part 603, test method H, is not helpful when it comes to determiningthe service life of a cable in energy chains, since theroller testing stand cannot provide any conclusive results andthere is no VDE test for special cables in energy chains.Differences in service lifeAt the beginning of 2002, a test to determine the service lifeof profibus cables in a real application was commissioned inigus’ test laboratory. The aim was to examine any differencesin the service life of igus’ CFBUS.001 Chainflex ® cableand another market leading profibus cable. The parametersrequired for the test were selected on the basis of data containedin the competitor’s catalogue:Catalogue detailsCross sectionGuaranteed lifetimeBending radiusDiameterCatalogue detailsTest item “A”Twin-coreprofibus cable(2 x AWG24)CMin. 4,0 Mio. Cycles> = 60 mm8,0 mmIssue 2002Test item “B”igus ® Chainflex ®CFBUS.001(2 x 0,25 mm 2 )CTo be determined ina test85 mm8,5 mmIssue 2002Test parameters according to catalogue data of the competitionA gliding application was chosen as a suitable test structuresince profibus cable systems are usually used here becauseof their data integrity, particularly over long lengths of traveland long transmission distances.In order to be able to carry out non-destructive testing andhence achieve a large number of bending cycles in a shortperiod of time, a genuine profibus transmission path waserected. In a PC at the fixed end of the test chain there wasa profibus master insert card. A connection to a profibus slavewas located on the moving end. This enabled the transmissionrate to be determined with the help of a diagnosis program.Any data packets which might have been transmittedincorrectly could be indicated. The highest-possible transmissionrate of 12 megabits/s was set.The fundamental test, which commenced at the beginningof 2002 and is still in progress today, showed that only arelatively low number of cycles (420.000) resulted in the totalfailure of test item “A“, which, according to the competitor’scatalogue, should have functioned safely for at least 4.0million cycles. Thus the real lifetime reaches only about 10%of the stated catalogue value.Picture: Sliding application as the basis of the test structureOn the other hand test item “B“, the CFBUS.001, is still undergoingtesting without any faulty data transmissions.So far, it has accomplished more than 14.0 million cycles.28