In order to meet the development needs of the third-generation smart substation

the developed composite combined electrical appliances with the advantages of simple structure

compactness

high reliability and easy installation and maintenance are the product basis for the development of the third-generation smart substation. This article introduces the two commonly used structures and performance parameters of the three-position combination switch of compound combined electrical appliances. The simulation analysis software is used to simulate the electric field of the three-position combination switch

and the strength of some components is checked. The calculation results show that the performance of the two three-position combination switches is safe and reliable. Moreover

its insulation

busbar conversion voltage（100 V）

induced current（Class B） switching and mechanical life M2（10 000 times） and other related type tests have smoothly been qualified

and the application of domestic and foreign power stations has verified the rationality of its design. The successful development of the three-station combination switch has realized the independent design and manufacture of composite combined electrical switchgear

and has provided equipment supports for the improvement and improvement of intelligent substations in the new era.