ABSTRACT
This chapter explores the electric arc, its structure, how is it formed, and how it is used to interrupt electric current. It discusses the current interruption process using the electric arc. In the context of electric contacts, the plasma is ionized gas that ‘burns’ between parted contacts and is called an electric arc, or arc for short. The arc formation depends entirely upon the properties of the contact material and the arc always initiates in metal vapor from the contacts themselves. Once an arc has been established between opening contacts, it requires a continuous supply of electrons from the cathode to sustain it. The primary cathode spot parameters that influence successful interruption at current zero are the high velocity of the ionized metal vapor away from the cathode surface, which leads to a rapid decrease in the inter-contact plasma density and the absence of a cathode spot at the new cathode.
