Parametric analysis of GMAW-P waveforms for the derivation of human exposure values

Different pulsed current waveforms, currently used for pulse gas metal arc welding (GMAW-P), have been analyzed from the point of view of human exposure to time-varying magnetic fields. The most common waveforms presented in the literature (i.e. trapezoidal, exponential and combined trapezoidal-exponential) have been considered for a parametric analysis, and the corresponding human exposure indexes related to induced current have been derived on the basis of the EN 50444 and EN 50445 standards. The calculations have been performed in the hypothesis of uniform magnetic flux density perpendicular to a homogeneous round disk. A specific code in Matlab has been developed. A parametric analysis has been performed, varying the frequency from 100 Hz to 400 Hz and the rise time from 10 μs to 500 μs, for all the considered current waveforms. The peak current has been set at 100 A, with a duration of 1 ms, value chosen according to the one droplet per pulse (ODPP) condition. Within the cases considered, as far as the human exposure indexes are concerned, their reduction when the rise time increases was found; moreover, it resulted that the analyzed current waveforms have quite similar impact in the evaluation of these indexes.