This paper presents several methods for diagnosing partial discharge (PD) in a Gas insulated switchgear (GIS) chamber using SF6 gas decomposed component analysis. Nine types of purposefully created defects within the chamber were simulated, resulting in PD and hence decomposed byproducts. In contrast to previous studies that only looked at specific aspects of PD analysis, this study employs decomposition component analysis to classify the defect type and assess the severity of SF6 gas decomposition. A series of experiments involving conducting and nonconducting defects were carried out.