May I ask a question about the single vs two phase stuff

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winnie said:
I have a terminology quibble with the above. Based on this discussion I absolutely agree that 180 degrees is a different phase angle than 0 degrees, and thus I agree than in a balanced '2 phase' system you will have _4_ distinct phase angles.

The terminology quibble is in how this is normally used. I will go back to the literature on 'high phase order' motors. In a conventional 3 phase motor you have at least _6_ phase bands in the stator; 3 for each of the supply phases and 3 for the inverses of these. The inverse phase bands are required because you have coils for each of the phase circuits, and thus half of the conductors travel down the stator slots in one direction, and half go the other way. But this is still called a _three_ phase motor. What the HPO people call a six phase motor generally has 12 phase bands, and can be understood as two three phase coil sets displaced by 30 degrees.

As I have seen the terminology used, terminals with phase displacements of 180 degrees are considered separate parts of the same 'phase' for purpose of counting system phases. Thus a phase displacement of 90 degrees (which I agree has 4 separate phase angles available) is _called_ '2 phase', and a phase displacement of 180 degrees is _called_ single phase. A phase displacement of 120 degrees is called 3 phase, but if you look at how 3 phase is used to run motors you will clearly see 6 separate phase angles in use.

An exception to this seems to be in transformers for rectifiers; 'hexaphase' transformers have 6 terminals with a phase angle of 60 degrees, and a transformer for a 12 pulse rectifier has phase angle differences of 30 degrees.

-Jon
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Thank you Winnie, the rectifier information just sealed it for me. It should have sealed it the first & second time it came up.

One Pulse per Phase per cycle with a single diode per phase. Use of a bridge diode configuration will double the pulses.


30 degree 12 phases & 12 pulses.

60 degree 6 phases & 6 pulses.

120 degrees 3 phases & 3 pulses

90 degrees (old 2-Phase) 2 pulses with uneven spacing

Split phase 2 pulses

Single phase 1 pulse
 
buffalonymann said:
electricity 101 - if there is no potential difference there is no current flow
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Except in a superconductor, of course. And there are current sources where the voltage is a result of the current flow, not the cause.
 
From my High School physics book: seems the dimensions for work & electric current don't match. The coulomb does not even appear in the dimension for work. The colour coding was just to keep my eyes from drifting from line to line.
 

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SG-1 said:
Thank you Winnie, the rectifier information just sealed it for me. It should have sealed it the first & second time it came up.

One Pulse per Phase per cycle with a single diode per phase. Use of a bridge diode configuration will double the pulses.


30 degree 12 phases & 12 pulses.

60 degree 6 phases & 6 pulses.
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A three-phase full wave rectifier has six diodes with one pulse every 60 degrees.
It is the most common input arrangement for VFDs.
 
jaggedben said:
I don't think it's proper form to add to the post count with this kind of witty banter. This thread should only get longer due to tendentious, intractable argument.
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We are just taking a break, we have plenty of time to argue how conventional names and descriptions do not always match the physical reality of what is actually there and that our descriptions are based on our point of reference.
 
Ingenieur said:
it has all been said
many, many times

I say 2 phases, 120 deg / 180 deg x 3 = 2 :sick:
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Which is described as a 1P 3W 120/240V service per NEC/IEEE.:D.

Not 2 phase! That is where the darn confusion to newbs arises.

Those of us who do our homework understand what you saying just fine.:)

Physics and NEC/IEEE naming conventions do not always match.
 
jumper said:
Which is described as a 1P 3W 120/240V service per NEC/IEEE.:D.

Not 2 phase! That is where the darn confusion to newbs arises.

Those of us who do our homework understand what you saying just fine.:)

Physics and NEC/IEEE naming conventions do not always match.
Click to expand...

it was a joke
the equation is nonsense :lol:

I never said it was a 2 phase power system
only that the sec is comprised of 2 waveforms seperated by 180 deg, hence comprised of 2 phases
 
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