Critical switching impulse breakdown of long bundle-conductor gaps

The paper presents a generalized physical approach to account for the effect of bundle geometry on critical switching impulse strength of long air gaps. The model covers phase-to-ground as well as phase-to-phase insulation. It has been applied to conventional symmetrical bundles as well as to more complex open configurations. The effect of bundle conductors was investigated for the following basic configurations: conductor-plane; conductor-rod; conductor-tower leg; conductor-tower window; and phase-to-phase, within a wide range of clearances. The model is compared with previous analytical approaches as well as to extensive experimental results.