When three-phase AC power is supplied to the device shown in figure "A" of the illustration, what is the characteristic of the output? See illustration EL-0063.
• Diodes only allow current to flow in one direction in a rectifier circuit. • A six-diode bridge connected to three AC phases is a three-phase full-wave rectifier. • Compare the input waveforms in part B with the combined output waveform in part C of the illustration.
• Look at how the diodes are arranged between the three phase inputs and the load: does the load ever see a reversal of polarity? • Compare the smoothness and direction of the waveform at the load with a normal AC sine wave: is it alternating above and below the zero line, or always on one side? • Ask yourself: is this circuit converting AC to AC, or AC to DC? And if DC, what special characteristic does three-phase give the DC output?.
• Verify whether the voltage across R_L ever changes polarity (swaps positive and negative). • Check if the waveform labeled C crosses the zero axis or stays on the same side while pulsing. • Confirm that each phase (A, B, C) takes turns feeding the load through the diodes, and note what that does to the direction of current through the load.
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