energies Article Correlation Characteristics Comparison of SF6 Decomposition versus Gas Pressure under Negative DC Partial Discharge Initiated by Two Typical Defects Dong Yang 1, Ju Tang 1, Xu Yang 1, Ke Li 1, Fuping Zeng 1,*, Qiang Yao 2, Yulong Miao 2 and Lincong Chen 3 1 School of ...