Abstract: Disclosed is a coupling arrangement of a DC welding apparatus, particularly intended for MIG welding. The coupling comprises a controllable fast DC voltage source, first circuit elements for detecting both load current and load voltage and for generating voltage signals corresponding thereto, second circuit elements for forming a control signal in response to said voltage signals so as to correspond to the values of desired current step and current increase rate in a drop short-circuit instance, and third circuit elements which receive the control signal and effect control of the voltage source in response thereto. Said second circuit elements may include means for receiving a setting signal by which the characteristic values of the current step and the current increase may be set and scaled and the open circuit-voltage of the voltage source can be determined.