| dc.description.abstract | Medium voltage load break switches are required to perform a number of making operation while passing of short circuit current that could be more than tens of kiloamperes. Using air-filled devices as an alternative to SF6, which is a high impact greenhouse gas, makes the switch more environmentally friendly but leads to more challenging making operation due to higher arcing times and dissipated energies between the contacts. In this case, the prestrike arc could lead to contacts welding and degradation, which is highly undesirable. This paper reports on an investigation of the pre-strike arc impact on erosion and welding of copper/tungsten (20/80) arcing contacts during short-circuit making operations. For this purpose, a synthetic test circuit consisting of a high current source in combination with a high voltage one is used. Experiments are conducted for different operation voltages, while the short circuit current is kept constant at 22 kA. Mass loss measurement and visual inspection of eroded/welded contacts are examined with regard to pre-strike arc impact on their degradation. The contacts are welded by three times repeating the test at operation voltage of 20 kV and short-circuit current of 22 kA and failed to re-open. Besides, an increase in the contacts’ mass loss with arcing time is observed while the making current is constant. This is an indication that the pre-strike arc energy highly impacts the switch reliability and service life. | en_US |
