Abstract: The author made a brief survey of the welding arc control system applied in. conventional arc welding machines and discussed the problems existing in them. In order to improve the welding arc behavior and consequent weld quality an original control concept (QH-ARC control) has been conceived. It can ensure stabic arc length and satisfactory metal transfer at both normal welding conditions and abrupt change of wire feed speed or any other type of arc disturbance. Therefore, it may be used as a means for realising profile welding, pulsed wire feed welding and one-knob controlled welding processes. Taking advantage of this control method a closed loop control of bead penetration and heat imput, may be obtained.

Key words: Carbon deposition Morphology Spectra analysis Spectra analysis Formation mechanism