Based on the analysis of stress variation during water pressure test and the manufacturing process of a three-phase closed insulating spacer for GIS/GCB

the failure of the insulating spacer in hydrotest is found to be caused by inner stress

especially the inner stress around the metal inserts. The inner stress mainly depends on the quality of the filler and the quality of the conductive rubber coating around the inserts. To reduce the inner stress and control the strength of water pressure of insulating spacer

it is necessary to meet the technical specifications of conductive rubber and filler

avoid poor adhesion between inserts and resin casting body

prevent filler from deposit during molding

optimize solidification process

and keep equipment stable.