CRITICAL SWITCHING IMPULSE STRENGTH OF PHASE-TO-PHASE AIR INSULATION

The paper presents a new physical approach to modelling of positive le ader inception and breakdown of phase-to-phase insulation in air, expo sed to critical switching impulses of synchronized peaks and opposite polarity. The work constitutes a generalization of a recently publishe d model dealing with phase-to-ground insulation and covers both conduc tor-conductor and horizontal rod-rod configurations. The influence of interphase separation, conductor height above ground, conductor radius and relative amplitude of the negative impulse on critical insulation strength is systematically investigated. A novel application of the m odel is a physically based prediction of air density effects on phase- to-phase leader inception and breakdown. The model findings are extens ively compared with experimental results.