The three phase to DC welding transformer is essentially three
of the single phase DC weld transformers coupled together on the
secondary side after the diodes. There are three separate magnetic
cores. The welding control synchronizes the pulse of current for
each of the phases into the primaries. The secondary circuits are
center tapped and joined together to make the common returns. The
outside of the secondary windings are rectified by a set of diodes.
The output of the diodes are all joined together to provide the
power distribution to the welding tool.
Three Phase to DC Current Waveform
The welding control takes care to synchronize the pulses. As shown
in the current output waveform, the control begins by pulsing phase
A+, then it will continue with B-, C+, A-, B+, and last C-.
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