Esab Ab

Ulf Lagerqvist

Peter Budai

A method of controlling a welding operation during arc welding between a fusible electrode and a workpiece, wherein the welding operation alternates between arc periods and short-circuiting periods, includes the steps of sensing a first parameter of the welding operation, for example the arc voltage between the electrode and the workpiece, generating a first signal representative of the first parameter, sensing a second parameter of the welding operation, generating a second signal representative of the second parameter, filtering the second signal to provide a filtered signal, generating a desired value signal based upon the filtered signal and controlling the welding operation based upon the difference between the desired value signal and the first signal. According to the method of the present invention, any changes in the second signal that occur at a frequency outside a predetermined frequency range, which includes a desired short-circuiting frequency of the welding operation, are attenuated such that the desired value signal is less affected by these changes than by changes occurring at a frequency within the predetermined frequency range. An apparatus for carrying out the method includes a band-pass filter having a pass band including the desired short-circuiting frequency.

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Lax.ANG., Sweden

Ulf Lagerqvist