PHENOMENA APPEARING AT THE SWITCHING-IN OF BACK -TO-BACK CAPACITOR BANKS WITH VACUUM CONTATORS OF 7.2kV

At the switching-in of back-to back capacitor banks, the rate rise and peak value of the inrush making current reach levels at which the switchgear contacts can be highly stressed. The paper presents the procedure and formulas by means of which the rate of rise and inrush making current amplitudes at switching can be computed for both back-to-back and single capacitor banks. The authors describe stresses to which the contact system of the vacuum contactor is exposed the physical phenomena appearing at prestrike and “hot” welding of contacts in vacuum, as well as the functional dependence of individual parameters that influence the welding temperature of the contacts. The test results confirm high switching characteristics in capacitor banks achieved with vacuum switchgear with the appropriate selection of contact materials