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6 SEPTEMBER / OCTOBER 2022 Wiring Harness News INDUSTRIAL INFO-TAINMENT

Intricacies of High Voltage Cable Processing

Martin Rosten , TE Connectivity

Since the 1970s , little has changed in automotive wiring . Manufacturers have added more wire and connectors , but everything still ties to legacy 12- volt systems . Thus , the architecture has remained basically the same . That is until the advent of HEVs and EVs . We have all heard the forecasts and read the OEM press releases about the coming electric fleets . And electrification doesn ’ t end there . Startups are testing and marketing electric buses , trucks , aircraft , lawnmowers … you name it and there is an electric version .

That ’ s really changing the landscape for cable assembly suppliers . A greater understanding needs to be gained about the intricacies of working
with large diameter cable . To learn more , we scheduled a zoom call with Martin Rosten , Global Sales and Field Service Director at TE Connectivity based in Bensheim , Germany . To say Martin is an expert on the subject would be an understatement . He ’ s not only studied it , he ’ s done it .
Following was our Q & A session with Martin .
WHN : Let ’ s start by defining a large diameter cable .
Martin : We usually define large diameter wire as anything over 10 mm ² ( 6 AWG ). The wire size is actually a function of the current needed in the vehicle . Hybrids go up to 150 amps and require about 30 mm ² wires . Complete battery electric vehicles have a much higher current requirement – up to 300 amps . There , we are already seeing sizes of 60 mm ² to 90 mm ². Even up to 120 mm ² cables will likely be common in the future .
WHN : What is the typical construction ?
Martin : The high voltage cables themselves are very different from low voltage wires . They are comprised of multiple layers ( Figure 1 ). Typically , you have an inner conductor with an inner insulation . Then
Figure 1 . Components of a typical shielded high-voltage cable .
you have an electric screen which is usually a tin-plated copper braid and , most often , a foil over top of that . This is to prevent the very high currents being carried in these high-voltage cables from interfering with the data connectivity or other systems present in the vehicle . And then finally , the cable has an outer jacket which
Figure 2 . Example of “ Footballing ” in a 120 mm ² cable .
is usually an orange silicone . Orange is the standard color to differentiate high voltage circuits in vehicles .
WHN : How are large diameter cables different as it comes off the reel ?
Martin : The first thing that you will notice with high-voltage cables is what we call “ footballing ”. Because these cables are extremely large and heavy , and fed off fairly large spools , you get this footballing effect ( Figure 2 ) which is basically where the wire end becomes slightly oval in shape . So , the first thing you have to do when you ’ re preparing the wire for a high-voltage cable is to make it perfectly round again . *
WHN : How is stripping these cables different ?
Martin : You have more or less four separate processes that you need to carry out to get the wire ready for crimping . First is removing the outer jacket . The secret here lies in cutting deep enough so that you don ’ t risk tearing the insulation , but not so deep as to damage some strands in the copper braid underneath . That can cause a very unpleasant short circuit in the high-voltage system .
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