RECTIFIER TYPE POWER SOURCES
The next popular power sources are of rectifier type. Three phase transformer (step down) connected to a rectifier to give DC output is the simplest form. These DC output rectifiers are available with flat and drooping characteristics.
The flat characteristic DC output rectifiers are used for MIG / CO2 welding and SA welding. The output voltage (arc voltage) selection is provided by a tap changing on the primary side of input transformer. The power factor and efficiency of these flat DC output rectifiers are very high. Rectifiers with drooping characteristics DC output are used for SMAW, TIG, plasma and sometimes SA welding. The current control is done by magnetic amplifier connected between secondary and rectifier. Compensation for line voltage fluctuations is also incorporated in some of the latest rectifier type powersources.