Fundamental of Welding Science and Technology NPTEL ANSWERS : WEEK 6 (Question 9-10)

 Fundamental of Welding Science and Technology NPTEL ANSWERS : WEEK 6 (Question 9-10)

9. In case of arc welding of steel with a potential of 20 V and current of 200 A, the travel speed is 5 mm/s and the cross-sectional area of the joint is 20 mm^2. The heat required for melting steel may be taken as 10 J/mm^3 and heat transfer efficiency as 0.85. The melting efficiency will be nearly:

 18 %

 29 %

 36 %

 42 %

B (NOT SURE)

1 point

10. A direct current welding machine with a linear power source characteristic provides open circuit voltage of 80 V and short circuit current of 800 A. During welding the machine, the measured arc current is 500 A corresponding to an arc length of 5.0 mm and the measured arc current is 460 A corresponding to an arc length of 7.0 mm. the linear voltage (E)-arc length (L) characteristic of the welding arc can be given as (where E is in volt and L is in mm)?

 E = 80 + 8L

 E = 80 + 2L

 E = 20 + 8L

 E = 20 + 2L

D