Interfacial Stress Between Conductor and Insulation material of GIS/ GIL Spacer Used in UHV

The Ultra High Voltage (UHV) basin-type spacer, which has typical insulation structure existing in many power equipment, is an important component in gas insulated switchgear (GIS) and gas insulated transmission lines (GIL). The spacer consists of a central metal conductor and an epoxy insulation composite. In the hydrostatic failure test, the mechanical damage of UHV spacer often initiates from the interface between center conductor and insulation material. Therefore, in order to find the reason why mechanical strength of the spacer is low, the stress of UHV spacer during the hydrostatic test must be analyzed. The stress distribution of the spacer during hydrostatic test has been simulated and calculated. By comparing the stress distribution during the hydrostatic test and the damage pattern after hydrostatic test of UHV spacer, the residual stress between center conductor and insulation material should be the main factor of the failure. Then the stress after manufacture process of UHV spacer is analyzed. It is found that the stress concentration area at the interface should be caused by the difference of mechanical properties between the metal conductor and the insulation material. The maximum axial and radial shear stresses at the interface reach 15.8 MPa. Therefore, effective measures must be taken to relieve the interfacial stress between the center conductor and the insulation material. Meanwhile, this analytical method for the interfacial stress in this article can be applied to the similar interfacial structure of other power equipment.