Precision ovens for thermal endurance evaluation of electricalinsulating material

摘要

It is shown how a commercially available oven can be easilymodified by means of an iso-box to arrive at a temperature variation of± 1 K for thermal endurance evaluations. The modified oven meetsall requirements as, for instance, given in IEC 216-4-1 or DIN 50 011,Part 12 with respect to construction and air flow. The temperaturefluctuation in particular does not exceed ± 0,5 K and atemperature gradient inside the iso-box may be neglected. It is alsoshown that, in case of twisted pairs, the uncertainty of measurement ofthe temperature that corresponds to the temperature index can be reducedto ± 4 K