Dry-type transformers can utilize advanced insulating materials, replacing conventional cellulose and mineral oil, for operation at higher temperatures than those prescribed in IEC 60076-2. Aramid insulation is frequently used due to its superior thermal class compared to cellulose. Studies, including those summarized in IEEE Std. 1276, demonstrate that the reference lifetime of 65,000 hours under specific test conditions allows for a higher normal operating temperature for aramid (188°C) compared to cellulose (95°C). Both IEEE and IEC standards provide temperature limits for high-temperature designs. IEC 60076-14 outlines these limits, along with definitions of insulation systems for high-temperature operation. Temperature limits vary based on the thermal class of the solid insulation and the type of insulating liquid used. For instance, aramid insulation with a thermal class exceeding 180 has higher temperature limits than materials with lower thermal classes, such as 155, 140, or 130.