Point to the defect of current use current as controlled, based on the analysis of the main circuit of the submerged arc furnace, the control strategy using molten bath resistance is introduced and the formu.

This model avoided the assumption of constant conditions of interface between welding arc and pool,and made analysis on behavior of arc and pool more near to real situation.

The results show that the home made ultrasonic wave equipment is suitable for detecting the size, configuration and location of the common defects in fused cast refractories under the given experimental conditions, some practicable ultrasonic wave testing parameters are provided too.