中文摘要：

由发电机出线直接升压到800kV的变压器将在西北地区首次采用。该文将结合拉西瓦工程设计的要求．对一系列的技术问题加以研究与分析。根据工程设计和研究结果．变压器将采用三相组单相变压器．铁心采用三柱式，电压调压范围为800／√3—3×2．5％kV。由于GIS的断路器和隔离开关均设置分合闸电阻．使GIS产生的快速暂态过电压（VFTO）对变压器绝缘影响较小．以及我国800kV系统过电压的限制水平．确定它的绝缘耐受能力．

英文摘要：

Associated with Laxiwa hydropower station, the 800 kV step-up transformer, which directly connects with generator, shall be adopted first in northwest. Some technical considerations are given to solve the problems appeared in design. Besides, according to technical design and preliminary research results, the three single-phase transformers, with a three-column core and a w~hage-regulation scope of 800/-3 × 2.5% kV, are chosen. As the pre-inserting resistance is used in CB and DS, the very fast transient overvohage produced in GIS will make little influence to the transformer insulation. With the overvoltage level of 800 kV rated voltages in China, preferred rated insulation levels are given.