# 12 Pulse Rectifier

Discussion in 'General Electronics Chat' started by PAB, Jul 1, 2007.

1. ### PAB Thread Starter New Member

Jun 21, 2007
6
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I have a 6 phase 380VRMS @50Hz supplied SCR rectifier, I need to know what is the voltage on the DC Bus between + and -.

I understand there is a simple formula to calculate this. Am I correct?

(Supply info: 3 phase PRI (415VRMS) supplied transformer @ 50Hz, and SEC output of 380VRMS on a DELTA Tap, and 380RMS on a STAR Tap.
gives 2 sets of 3 phases with a phase difference of 30degrees (if you impose the star winding over the delta). Once (SCR) rectified there will be 12 pulses).

I have posted this question before and no-one replied.

Nov 1, 2006
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The info I have for a 6-phase, full-wave rectifier circuit, assuming 180 degree SCR firing angle is 2.336 times your RMS phase-to-phase voltage or about 887VDC, although, to me, this seems high. This same book shows that, for a six-phase, half-wave rectifier circuit you multiply the phase-to-phase RMS voltage by a more reasonable 1.35 to get your DC output voltage. Hope this helps.

3. ### PAB Thread Starter New Member

Jun 21, 2007
6
0
Dave, This 2.336 formula does not seem correct, as I have been informed that there is over 1100V DC present on the bus. It sounds about right for a 3 phase rectifier though as it would have 6 pulses present on the DC Bus.
On the 6 phase rectifier DC bus there would be 12 pulses over the space of 50Hz (every 20milli seconds).

Any other suggestions?