The invention relates to the field of automated welding, and more particularly, to an automated, gas metal arc welding apparatus for externally welding abutting sections of pipe. The power array including a switch array, responsive to independent drive signals, to convert the input voltage to the chopped output at a switching frequency. Such a drag chain provides a sound-damping which does not entail the deposit of dirt on the support or the guide channel, and which can be reliably installed and supplied in a pre-assembled state with a pre-manufactured system.