Environmental EMC aspects of resistance welding equipment

Resulting from the connection between the change rate of a magnetic field and the induced currents in an exposed human body, pulsating magnetic fields have to be evaluated analysing the waveforms of the field or the field-generating current A corresponding assessment guideline is given in the German safety regulation on "Electromagnetic Fields" BGV Bll. Considering the specific output current waveforms of resistance welding installations, in the paper appropriate procedures to determine the waveform-dependent exposure limits are explained by the examples of an a.c. resistance welding machine and a resistance welding inverter. Based on investigations of the field distribution the occurring actual flux density values are compared to the ascertained exposure limits and a practical method to determine minimum distances ensuring compliance with the given regulations is shown.