On the premise of ensuring the technical performance of 126 kV GIS and for meeting the lightweight and compact needs of power users

the goal of reducing product weight and external dimensions is achieved by improving the product structure

increasing its design flexibility

and reducing the weight of bays

thereby reducing the load requirements for civil work. In this paper

the structural characteristics and performance parameters of a kind of lightweight 126 kV GIS is introduced. The simulation analysis software is used to optimize the airflow field of the interrupter unit of circuit breaker and simulate the electric field of the circuit breaker module and three working position module under various working conditions. Moreover

the strength of the circuit breaker and three working position enclosures is also verified so to meet the mechanical performance requirements of lightweight 126 kV GIS. The calculation results show that the interrupter

three working position and overall structure of the lightweight 126 kV GIS are reasonable in design

which assures the successful pass of various type tests items and lays a theoretical foundation for the subsequent lightweight design of GIS.