Hybrid Switch with Tungsten-clad Copper Contacts for Arc-free On/Off Switching up to DC 400 A

Abstract

Direct current (DC) switches are one of the key components  of  DC  power  distribution  systems.  During  the closing  and  opening  periods  of  the  switch,  arc  discharges  are generated causing contact erosion and a reduction of dielectric strength between the contacts. A hybrid DC switch, consisting of mechanical  contacts,  semiconductor  devices,  and  metal-oxide varistors, can shorten the arc duration; however, a short duration arc still causes contact erosion and induces a reignition of the arc. Arc-free  DC  switching  up  to  400  A  for  closing  and  opening periods is demonstrated using tungsten-clad copper contacts anda  SiC-MOSFET  module.  The  tungsten  part  of  the  contacts increases the boiling voltage of the latter, and the copper part decreases  the  maximum  temperature  at  the  contact  spot.  Both parts are crucial to achieving arc-free switching.