What type of volt-amp curve does a constant current machine produce?

What type of volt-amp curve does a constant current machine produce?

• A. Drooping
• B. Variable
• C. Rising
• D. Flat

Answer: (A)

In a constant current welding machine, the current is held nearly constant while the arc voltage varies with arc length and other conditions. As you increase the current setting, the machine maintains that current, but the arc voltage tends to drop rather than rise. This makes the volt-amp curve slope downward, so it’s described as a drooping curve. Why this fits: a flat curve would imply voltage stays the same as current changes, which is typical of a constant voltage (CV) source. A rising curve would mean voltage increases with current, which isn’t how CC machines regulate the arc. The key idea is that CC power supplies keep the current steady, and the voltage needed to sustain the arc decreases somewhat as you push more current, producing a drooping VA relationship.

In a constant current welding machine, the current is held nearly constant while the arc voltage varies with arc length and other conditions. As you increase the current setting, the machine maintains that current, but the arc voltage tends to drop rather than rise. This makes the volt-amp curve slope downward, so it’s described as a drooping curve.

Why this fits: a flat curve would imply voltage stays the same as current changes, which is typical of a constant voltage (CV) source. A rising curve would mean voltage increases with current, which isn’t how CC machines regulate the arc. The key idea is that CC power supplies keep the current steady, and the voltage needed to sustain the arc decreases somewhat as you push more current, producing a drooping VA relationship.