Investigation of the electrical performance of epoxy/ silicon rubber interface
Design of a standardized 145 kV inner-cone GIS cable termination
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Abstract
The CIGRE B1 – B3.49 JWG defined a standardised 145 kV inner-cone GIS cable termination design. This standardisation allows the creation of new common interface insulators. This would eliminate the planning hurdles due to the fact that the cable system is not usually defined at the time of switchgear manufacture. The new design also requires a detailed study to find the relation between interfacial pressure and electrical performance of the epoxy/ silicon rubber interface.
The first step is to design and build a test setup to study the epoxy/ silicon rubber interface. Next, AC breakdown and lightning impulse tests are carried out. Additional AC breakdown testing with oil at the interface, defects on epoxy and heated samples are also carried out. The relation between interfacial pressure and electric field strength of the interface is found and documented. The effects of lubricant, defects and heat is used to further characterise the interface. Simultaneously, the silicon rubber is modelled using hyperelastic material modelling techniques.
The results from the tests and FEM models are used to propose two new designs of the 145 kV inner-cone GIS cable termination. The high repeatability of breakdown values and distinct features of this test setup have prompted the sharing of the experimental setup and results through an IEEE publication.