Question

A 20 V supply is used in a shielded arc welding operation on a carbon steel with electrodes of the same material. The cross-sectional area of the weld is 72 mm${}^2$. The specific energy to melt a metal for carbon steel is 12.3 J/mm${}^3$. The welding speed is 10 mm/s and efficiency of heat input is 75%. The required current current is

• A. 750 A
• B. 705 A
• C. 650 A
• D. 590 A

Answer 1

The correct option is D 590 A

For equilibrium, the heat input to the melt is equal to the electrical energy,
thus

$uvA=\eta VI$

$I=\frac{uvA}{\eta V}$

$=\frac{12.3\times 10\times 72}{0.75\times 20}=590.4A$