Local Temperature Reduction in Thin Wire Cables Due to Contacted Thermocouples

Complex cable systems for various applications need to be protected from over-current-induced high temperatures. That is why the cable temperature has to be monitored. Temperature measurement especially in thin wire cables can be challenging. Many measurement approaches only allow the surface temperature measurement and therefore are not appropriate for monitoring the inner cable temperature. Others, such as the widespread thermocouple temperature measurement, can relevantly change the cable temperature and therefore lead to deviations between the measured temperature and the real cable temperature without connected measurement equipment. This effect is studied in this article. For comparison, an indirect temperature measurement approach is presented that is based on the cable’s resistance measurement. Subsequently, the temperature drop due to a connected thermocouple is measured. An analytical model for the description of this effect is proposed and validated. Finally, based on parameter studies, a rule for selecting suitable thermocouples is derived.