Thermal aging behavior of the oil-impregnated paper at 160/spl deg/C

The load change of locomotive transformer used in the electric rail road is not smooth and regular. Its overload coefficient is also changeable, sometimes might be either zero or up to 3.0. The situation could cause the partial temperature rising in the transformer, extremely, the temperature, in short time, can be higher than 140/spl deg/C, even might reach 160/spl deg/C. It brings about new problems to the insulation of the transformer. Despite of having enough experience standard in the IEC which has been admitting, yet the thermal aging behavior of higher than 140/spl deg/C about oil-impregnated paper has not substantial experiment law to be abided by the designer and manufacturer. In this paper, some information is published about thermal aging characteristic of the oil-impregnated paper at 160/spl deg/C.