Which current phenomenon is eliminated by reversing current in an AC circuit?

Which current phenomenon is eliminated by reversing current in an AC circuit?

• A. Arc blow
• B. Arc shine
• C. Arc flicker
• D. Arc static

Answer: (A)

Arc blow is caused by the magnetic field generated by the welding current pushing the arc off its path. When you use direct current, that magnetic field stays in one direction, so the arc drifts consistently to one side. In an alternating-current circuit, the current reverses every half cycle, so the magnetic field also reverses. The arc is pushed first in one direction, then in the opposite direction, and those forces cancel out over a full cycle. The result is no sustained sideways push on the arc, so arc blow is eliminated or greatly reduced. Other AC-related arc behaviors exist, but they don’t disappear simply because the current reverses; the key point here is that the steady magnetic force causing arc blow is removed by the reversal of current.

Arc blow is caused by the magnetic field generated by the welding current pushing the arc off its path. When you use direct current, that magnetic field stays in one direction, so the arc drifts consistently to one side. In an alternating-current circuit, the current reverses every half cycle, so the magnetic field also reverses. The arc is pushed first in one direction, then in the opposite direction, and those forces cancel out over a full cycle. The result is no sustained sideways push on the arc, so arc blow is eliminated or greatly reduced. Other AC-related arc behaviors exist, but they don’t disappear simply because the current reverses; the key point here is that the steady magnetic force causing arc blow is removed by the reversal of current.