Apparatus for resistance welding with different welding currents has a welding transformer having a primary and a secondary side. Two welding electrodes are connected at the secondary side to the welding transformer and are each arranged on a respective control arm, one of the arms being movable by an actuating drive. A control and regulating arrangement is connected on the primary side between the welding transformer and a connection to a three-phase network. The control and regulating arrangement has a rectifier circuit connected to all three phases of the network and a controllable welding inverter for converting the rectified voltage into voltage pulses of alternating polarity at a predetermined frequency. At least one electronic component of the rectifier circuit and/or the welding inverter is connected to the drive for moving one of the control arms, for controlling and/or powering the drive.