In order to enhance the insulation strength of environmental Ring Main Unite（RMU）

this paper presents a novel design scheme for the RMU solid-insulation-embedded pole

in which the vacuum interrupter and three-position-switch are both sealed with epoxy resin or other insulating material as a whole.As a result

composite insulation is made full use to reduce or avoid the insulation weak links and faults.Meanwhile the structure arrangement becomes rather simple and compact.Based on the design scheme of embedded pole a novel environmental ring main unit is developed strictly according to State Grid’ s standardize demands.The calculation of the 3-D electric field and insulation analysis are then conducted.And type tests are also carried out.The results show that the new designed ring main unit switchgear possesses rather good insulation strength and can endure the insulation test under zero-gauge pressure.