With the development of GIS from single-phase in an enclosure to three-phase in an enclosure

many new topics have emerged.When the short-circuit fault occurs

the electromagnetic force of the three-phase bus is about tens times as that of the single-phase bus.Such a large electromagnetic force must be borne by the three-phase bus insulated basin

so its inter-phase mechanical strength is particularly important.At present

there are few relative standards and technical data about the inter-phase mechanical strength of three-phase bus insulated basin

GIS equipment manufacturers are based on their own internal standards for testing.Few experiments have been carried out to verify the mechanical properties of the interphase which is inconsistent with the actual operation of three-phase GIS.This paper presents a test device and test method for interphase mechanical test for reference.According to GB7674-2008 APPENDIX B "GIS test method under internal fault arc condition"

for the three-phase common enclosure GIS

the three-phase arc test of arc burning between phases should be carried out

that is

the arc burns between phases and does not last between the bus conductor and the enclosure.It is not appropriate to use the enclosure burn-through time to check the external effect of the arc.In this paper

it is put forward that the duration of explosionproof film is reasonable to evaluate the external effect of arc.Finally

the bad partial discharge problem of GIS in mass production is analyzed and verified by experiments

It is believed that this is caused by the assembly air gap discharge between the the three-phase common enclosure insulated basin and its external metal flange

the problem was solved by applying conductive adhesive to the periphery of the insulated basin before assembly.At the same time

it is pointed out that for the assembled insulated basin with external metal flanges

it will be helpful to improvethe performance of partial discharge of GIS if proper metal shielding ring is added in the interior of low potential areaduring the development and design. Through the theoretical analysis of these issues

we can provide valuable experience for GIS research and development

mass production and safe operation.