What will be the output voltage of a 480 VAC Step Down Transformer connected to a 3 phase rectifier?

To determine the output voltage of a 480 VAC three-phase step-down transformer connected to a three-phase rectifier, it's essential to understand how conversion from AC to DC works in this scenario.

When a three-phase AC supply is rectified, the output DC voltage is related to the root mean square (RMS) voltage of the AC input. The RMS voltage of a three-phase system is given by the formula (V_{DC} = V_{L-L} \times \sqrt{3}), where (V_{L-L}) is the line-to-line RMS voltage. In this case, the line-to-line voltage is 480 VAC.

However, when rectifying this three-phase voltage, one must account for the average output voltage of the rectifier. The output voltage of a three-phase full-wave rectifier can be approximated as:

[ V_{DC} = \frac{2 \cdot V_{L-L}}{\pi} ]

For a system with a phase voltage of 480 V RMS, we convert this to the DC output as follows:

1. Calculate the peak voltage from the RMS voltage:

[ V_{peak} = V_{L-L} \times \sqrt{2} =