|
The main component of vacuum interrupters responsible for ensuring the correct
flow of current is the contact system. In a vacuum environment, due to the higher values of
the mean free path of electrons and particles in the contact gap, the material and condition
of the contacts exert the greatest influence on the development of the arc discharge. To ac-
curately analyze the phenomenon of discharge development in vacuum insulating systems,
the authors conducted a time-lapse photographic analysis of a vacuum electric arc. For
this purpose, they used a test setup comprising a discharge chamber, a vacuum pump set,
a power and load assembly, an ultra-high-speed camera, and an oscilloscope with dedi-
cated probes. The measurement process involved connecting the system, determining the
power supply, load, and measurement parameters and subsequently performing contact
opening operations while simultaneously recording the process using the oscilloscope and
ultra-high-speed camera. An analysis of a low-current vacuum arc in a residual helium
gas environment, with a pressure of p = 1.00 × 101 Pa was carried out. Different phases of
vacuum arc burning between electrodes in the discharge chamber were identified. In the
stable phase, the arc voltage remained constant, while in the unstable phase, the arc voltage
increased. The results of the time-lapse analysis were compared with the characteristics
recorded by the oscilloscope, revealing a correlation between the increase in vacuum arc
voltage and the intensity of flashes in the interelectrode space. The movement of micropar-
ticles ejected from the surface of the contacts—either reflecting or adhering to one of the
electrodes—was observed. This analysis provides a deeper understanding of the processes
involved in discharge formation and development under reduced pressure conditions. Un-
derstanding these mechanisms can support the design of vacuum interrupters, particularly
in the selection of suitable contact materials and shapes.
|
