how the 12 pulse rectifier is made?

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Question Posted / himanshu jain

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how the 12 pulse rectifier is made?..

Answer / suneetha

12 pulse rectifier is made of two 6 pulse rectifiers in
which 1 rect s connected in star n oder in delta.The input
side is connected in parallel and the o/p side in series

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how the 12 pulse rectifier is made?..

Answer / venu

Is it possible to obtain more pulses than twice the number
of phases in a rectifier circuit? The answer to this
question is yes: especially in polyphase circuits. Through
the creative use of transformers, sets of full-wave
rectifiers may be paralleled in such a way that more than
six pulses of DC are produced for three phases of AC. A 30o
phase shift is introduced from primary to secondary of a
three-phase transformer when the winding configurations are
not of the same type. In other words, a transformer
connected either Y-Δ or Δ-Y will exhibit this 30o phase
shift, while a transformer connected Y-Y or Δ-Δ will not.
This phenomenon may be exploited by having one transformer
connected Y-Y feed a bridge rectifier, and have another
transformer connected Y-Δ feed a second bridge rectifier,
then parallel the DC outputs of both rectifiers. (Figure
below) Since the ripple voltage waveforms of the two
rectifiers' outputs are phase-shifted 30o from one another,
their superposition results in less ripple than either
rectifier output considered separately: 12 pulses per 360o
instead of just six: