Simulation and experimental study on mechanical performance of UHV GIS spacer in hydrostatic test

Gas insulated switchgear (GIS) spacer is required to be of good electrical and mechanical properties to ensure high safety and reliability. The requirements are stricter for ultra high voltage (UHV) GIS spacer under higher voltage and pressure. In previous studies, the insulation characteristics of GIS epoxy spacer were investigated. But researches on the mechanical properties of the GIS spacer were rarely reported. In this study, UHV GIS spacer in hydrostatic test is simulated with the finite-element method. Strain and stress distributions along spacer surface are investigated. Results indicate that the maximum stress appears on the spacer surface near flanging ring, where cracks usually occur. Based on the calculation results, fiber Bragg grating (FBG) sensors are placed on UHV GIS spacer surface to monitor the strain variation in hydrostatic test. Measured results present a strain distribution similar as calculation results. The calculated failure pressure is consistent with those of tested spacers. The crack initiates in the proximity of sealing groove as predicted in calculation.