Uncontrolled pulse spark gaps with increased operation stability

Results of investigations into the pulse break-down of an uncontrolled spark gap with inhomogeneities at the grounded electrode and having a third electrode, located at the dielectrical substrate, placed on the grounded electrode surface, are presented. Spark gaps were investigated in SF6 gas under 0.35 MPa pressure and 5mm insulation spacing. Within the range of (0.2-1.5)1012 v/s voltage pulse rise average slope change and under 120 approx. 140 kV operation voltage, uncontrolled spark gaps with a dielectrical insert at the 16 mm diameter grounded electrode and the third electrode are characterized by ≤ 10 ns break-down delay time spreading. Their break-down voltage is weakly dependent on the voltage pulse rise slope change