Effect of Time Shift Between the two Voltage Components on Phase-to-Phase Insulation Strength

A study on the phase-to-phase strength of a conductor-conductor configuration was performed in IREQ´s High-Voltage Laboratory in an attempt to determine the influence of a time shift, ATcr, between the positive and negative voltage components on the 50% breakdown voltage. The gap tested was formed by two parallel conductors 6.7 m apart. Positive impulses of up to 2.3 MV, negative impulses of up to 3.2 MV and time shifts of up to 7.5 ms were used. The breakdown voltage, space charge and electric field on the electrode surface were monitored during the tests and photographs were taken with an image-converter camera.