Investigation of the Plasma of a DC hybrid-switch model at beginning of contact separation

Electrical and optical methods permitted to characterize the plasma of a hybrid-switched DC-current discharge at the beginning of contact separation. The experimental setup consists of a model switch, which employs a linear motor as mechanical drive. A semiconductor connected in parallel to the contacts allows commutating the current after a given arcing time and therefore a hybrid switching. Firstly, the current flow remains initially through the contact path due to lower resistance of the closed contacts. During contact opening, the resistance rises due to reduced contact force, finally ending up with a single metal bridge that will be heated until explosion, leading thus to a metal-dominated discharge plasma. Through the commutation of the current to the low resistive semiconductor path, the arc is extinguish. An also parallel-connected MOV takes over the residual energy after current zero, preventing a higher voltage between the electrodes, which could re-ignite the arc. To capture the radiation of the arc plasma were combined high-speed imaging and time resolved spectroscopy. First results of the arc plasma characteristics during the short length and short duration arc were obtained.