Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
The capabilities and advantages of vacuum interrupters
(VIs) have been widely recognized on switching and
controlling the fault currents in medium voltage level. Due to
its environmental friendliness, there were various research and
developments for using VIs in transmission and distribution
lines. An axial magnetic field (AMF) electrode has more
advantages of the switching capability than other contact
designs such as reducing the arc voltage, securing higher
current value for transferring from the constriction arc to the
diffused arc and regulating the arc current distribution. The arc
constriction should increase the heat flux and the local
temperature on the electrodes and result in the surface melting,
which has undesirable influences on the characteristics of
vacuum arc and surroundings. In the present study, we
considered two different types of AMF electrodes used widely
in industries, one is coil type and the other is cup type, to
investigate the effective arc area and the thermal characteristics
by high-current vacuum arcs through three-dimensional FEM
analysis. Calculated results were compared with the results by a
commercial package, MAXWELL 3D, which is a reliable
analysis tool for the electro-magnetic fields, to validate the
present calculation.
