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Comments on Why arc welding does not require high voltage to arc?

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Why arc welding does not require high voltage to arc?

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I've heard that arc welding is getting done with low voltage. I believe arcing requires high voltage. Then how is arc welding done with about 50 volts? I thought we need kilovolts for arcing. Why? Any idea?

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It takes high voltage to start the arc. Once started, the air is ionized, and becomes fairly conductive. It then takes much less voltage to keep the current flowing to sustain the arc.

This also explains why you have to touch the terminals together to start the arc. Touching shorts the output, which gets the current flowing to the desired level. At that point the voltage is basically 0. The welder has a large inductor in series, so that the current continues to flow immediately after the terminals are moved apart. That causes the high voltage, which ionizes the air, which allows the voltage to go down again.

This is a case where inductive kickback is actually harnessed to do something useful. As Andy pointed out in a comment, other examples are switching power supplies like boost and flyback converters. Otherwise, we design circuits so that the inductive kickback from abruptly disconnecting a coil flows harmlessly to avoid making high voltage and damaging something.

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Works for me (1 comment)
Usually we design circuits so that the inductive kickback from abruptly disconnecting a coil flows somewhere harmlessly to avoid making high voltage. (1 comment)
Usually we design circuits so that the inductive kickback from abruptly disconnecting a coil flows somewhere harmlessly to avoid making high voltage.
Andy aka‭ wrote about 1 year ago

Except for the very useful case of the flyback converter!!