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Type0 cable heating. G.Gariano, C.Gemme, L.Rossi, F. Vernocchi INFN Genova Type0 cables will heat-up because of the Joule effect The cooler we can keep the cables, the lower the power because D R Al / D T~-0.4% per degree .
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Type0 cable heating G.Gariano, C.Gemme, L.Rossi, F. Vernocchi INFN Genova • Type0 cables will heat-up because of the Joule effect • The cooler we can keep the cables, the lower the power because DRAl/DT~-0.4% per degree. • We here try to evaluate the temperature the cable may get to and the actions to be taken. • We look at a 6-cable bundle of 80 cm mean length (min=75cm, max=85cm) and 2 Al conductors per Vddd and Vdda . We choose Iddd~0.9A and Idda~1.2A per cable giving a power of ~6W on the bundle and we see how the bundle heats-up 25/11/03
Temperature measured with a PT100 inside the cable bundle (if outside +2.5oC typ.) If the cable is “alone” DT increases only by ~3oC above ambient. T-gain when (loosely) tacked to stave
Cable bundle reaches Tasymptote in 3’ to 4’, Ta is ~20oC above ambient if the cable is “free” (~25oC above if in a confined space (a plastic tube of 50 cm and 1.6cm dia.)). • The bundle has been tacked to a stave cooled by liquid. The tacking has been done in 2 positions 20cm apart for a length of ~1cm using SE4445. Tstave~10oC, Tambient~25oC Tack1(T~20) T~30
Tack2(T~20) Heat on connectors is not negligible
Tacking to stave Omega with SE4445 helps in keeping T low. Already with two tacks we gain some 15oC. • More measurements must be done (with cool stave in cool environment), but running the cable at 10oC or below seems possible. • The power dissipated in the cable at various temperatures has been measured and ranges from 5.8W@<T>~0 to 6.3W @<T>~40C. The T-dependence is weaker than expected. • Running cold may imply some 5% less power (and less DV) than measured at room temperature. • Tacking cables to back-of-stave or other cool parts must be studied and should be implemented for safer handling and operation.