Magnetic field emissions up to 400 kHz from a welding equipment

This paper reports on the experimental characterization of a commercial industrial welding equipment with respect to magnetic field emissions up to 400 kHz. The frequency range of this analysis is due to the fact that the equipment under test is a manual metal arc (MMA) welding power source using inverter technology and an active dynamic control, resulting in frequency components in the tens and hundreds of kHz range. A simple and low cost new measurement probe consisting of three mutually perpendicular concentric coils for magnetic field analysis up to 400 kHz has been developed. This equipment has been combined with a commercial one for the analysis at low frequencies down to 5 Hz. Experimental data have been obtained at 400 A, maximum current for the equipment under test, with a resistive load corresponding to an MMA conventional load voltage of 36 V, in agreement with Standard EN 60974-1. Further analysis has been performed on the emissions from the welding cables. Frequency-selective field measurements have been obtained and the results are discussed with respect to occupational exposure limits.