Contact and nozzle wear from 100 interruptions for a puffer-type air load break switch

One type test requirement for medium voltage load break switches is to interrupt 100 consecutive "mainly active loads". A puffer-type switch with axial-blown arc has been tested according to the 630 A/24 kV ratings. The nozzle and contact wear were measured regularly to investigate design requirements and the impact from nozzle wear on gas flow. The contact wear is only moderate, while the nozzle wear causes a decrease in pressure build-up, which in turn may influence the interruption performance.