Disconnector is an important device of gas insulated switch gear（GIS）

and temperature rise test is one ofthe key links of its type test. In order to evaluate the temperature rise of a disconnector in high current condition moreaccurately in its development stage

this paper proposes a calculation method based on equivalent thermal-circuitmodel according to the heat transfer theory

in which the factors such as skin effect

contact resistance

and heat dissi-pation impedance

as well as the three-phase enclosed design

are considered. The results of calculation and testshow that the proposed method can give relatively accurate temperature rise of the key nodes of the three-phase en-closed disconnector for development of new products.