Twelve pulse rectifiers are frequently applied in applications such as heating, ventilating and air conditioning because of its harmonic reduction capability. A typical 12 Pulse rectifier consists of 12 diodes and a three-phase supply. The three-phase supply is converted into constant DC voltage. In a 12 Pulse controlled rectifier the three-phase supply is given by a wye to wye and delta transformer connected to two three-phase controlled SCR bridges converting 3 phase AC to DC .
This simulation circuit shown below consist of a three phase-three winding transformer with two 6-Pulse rectifier connected in series employing 12 pulse configurations, forming a Transformer Rectifier Unit.