Temperature rise simulation of coil winding on transformer and the consideration on the permissible current load

摘要

Transformer's life time is generally estimated about 30 years under 95℃ at maximum coil winding temperature. But, it is quite difficult to measure constantly coil winding temperature even in factory not to mention in field. Consequently, transformers are operated under 75℃ at cooling materials(oil or SF{sub}6 gas) to maintain coil winding temperature under 95℃ in fields. To calculate primary and secondary coil winding temperature and electrical magnetic core temperature, in this thesis appropriate differential equations are developed and simulated for some transformers operated in field. It is effective further to compare the 「STANDARD CHARACTERISTICS」 on transformer temperature rise which are shown in「OIL IMMERSED TRANSFORMER OPERATING SCHEME : THE ELECTRICAL ENGINEERS OF JAPAN'S TECHNICAL REPORT No. 143」 with the real transformers in fields. In addition above,the consideration on the permissible current load is also shown in this thesis.