DYNAMIC BARRIER EFFECT IN BREAKDOWN OF LIQUID DIELECTRICS

The dynamic breakdown process in a transformer oil has been studied for a point-plate gap of 2-4 cm when subjected to a 2.0/50 mu s voltage pulse of 300 kV. It has been established that a partial abrupt drop in voltage (30-60%) at the breakdown stage, whether followed by or not followed by a voltage recovery, results in loss of conductivity of the leader channels and in breaking of the connection between the ionization zone and the high-voltage electrode. A form of barrier is produced by a low-mobility volume charge, referred to as the dynamic barrier, which increases the gap strength by a factor of 2.4-1.5. The results obtained are of interest both for the physics of electrical breakdown in liquid dielectrics and for their practical applications.