Switehing Impulse Strength of Air Insulation: Leader Inception Criterion

The paper introduces a general criterion for leader inception of phase-to-ground air insulation under positive critical switching impulses. The new leader inception criterion establishes the correspondence between continuous leader initiation in the vicinity of the highly stressed electrode and conditions prevailing later at the instant of the final jump. The criterion is then applied to several complex electrode configurations including rod-rod, conductor-rod and conductor-structure gaps, where both analytic and digital techniques are used to compute the leader inception voltage, 50% breakdown voltage and gap factor. The theoretical predictions are systematically compared with available experimental results.