In this work was investigated the formation of an electric arc. The cutting of metal detail was carried out in fluid by the rotaried disk. As a result were determined the modes of polar effect for a material melting and value of a current density in an anode spot of an electric arc. It was made for the range of currents I=500-5000A. The calculation procedure of an expanding plasma cavity in water was developed. The basic parameters of plasma in the presence of material evaporation were determined. The geometrical sizes of expanding gas cavity, and also cavity pressure depending on parameters of electrical arc discharge were determined.
Regarding operating variables of installation were made the recommendations which based on conditions of an electric arc initiation and duration of an arc burning. It allows to ensure heightened productivity and efficiency of installation, and also to determine the main regularities of electrophysical and electro-hydrodynamical processes which influencing to the service properties of equipment.