In order to solve the problem of uneven electric field and poor reliability of the withdrawable switchgear.The paper presents a novel design scheme of the air insulation metal-enclosed switchgear

which combines the advantages of removable and fixed switchgears.Its main features are as follows:the three-phase main circuits are longitudinal layout from back to front if looking from the front of the cabinet

and the main circuit is mainly composed of circular conductors

with a linear moving disconnecting switch on each side of the vacuum interrupter.The reasons for this design and the ways to achieve it are discussed.The model’ s electrical field is calculations by finite element method

the results show that its electric field is obviously superior to the switchgears which usually adopt rectangular conductors.A typical 12 kV/1 250 A product prototype of this design is manufactured and tested.Its width is only500 mm.The partial discharge of the whole switchgearis less than 10 pC

and the main conductive circuit is greatly shortened

so a lot of material is saved accordingly.It is achieved that the switchgear combines the characteristics of miniaturization

with two-side disconnectors and excellent insulation performance

which promotes the diversified development of medium voltage switchgear.