So - how many phases?

[wirenut1980]

I might get banned for this, but what about an open wye-open delta bank? 2 phases on the primary with 3 phase secondary.

 

[iwire]

HEY - I get to declare the winner; or at least declare we have a consensus.

Sorry, just call me Alexander Haig.

 

[charlie b]

I see no liquids and no gases, so I conclude that only the solid phase is represented by your sketch. For that reason, I voted for ONE. :happyyes:

Also, if you look at the voltage between any two points on the secondary, and compare it to the voltage between any two other points, and disregard any minor changes that voltage drop might inflict, you will see two wave forms that match one, and only one of the following two descriptions:

• Both reach their positive peaks at the same time, both reach their negative peaks at the same time, and both reach their zero crossings at the same time.
• Both reach their zero crossings at the same time, and each reach its positive peak at the same moment the other reaches its negative peak.

That makes it "single phase," in my book.

 

[mivey]

Check eBay for a .0000004 Hz scope. eBay has everything.

No love for the Nyquist rate?

 

[mivey]

Good points.

Assume the applied primary voltage is characterized by the general function V(t)= A sin(ωt+φ₀), where A, ω and φ₀are constants. Apply any arbitrary set of turns ratios you desire between the primary winding and secondary taps.

We agree on what to call the device (YEA). Not sure we agree on why yet - but we seem to be getting there.

Ok, a sinusodial input on the primary.

Given that a definition of phase has not been specified, I will make the stipulation that my technically correct definition still stands. I will further stipulate that we are not considering the number of phases present in the circuit due to currents (or we could get the 30-something? that pfalcon mentioned based on a technicality). While I'm stipluating I might as well stipulate that the voltage magnitudes on the secondary are all equal for the voltages we are considering.

With that, we can have voltages with a phase of (ωt+φ₀) and voltages with a phase of (ωt+φ₀+180?). So, using the technically correct definition for phase and the stipulations I noted, we can have up to two phases present at any given point in time.

However, it is still called a single-phase transformer.

 

[rbalex]

Ok, a sinusodial input on the primary.

Given that a definition of phase has not been specified, I will make the stipulation that my technically correct definition still stands. I will further stipulate that we are not considering the number of phases present in the circuit due to currents (or we could get the 30-something? that pfalcon mentioned based on a technicality). While I'm stipluating I might as well stipulate that the voltage magnitudes on the secondary are all equal for the voltages we are considering.

With that, we can have voltages with a phase of (ωt+φ₀) and voltages with a phase of (ωt+φ₀+180?). So, using the technically correct definition for phase and the stipulations I noted, we can have up to two phases present at any given point in time.

However, it is still called a single-phase transformer.

You need to check your understanding of stipulate. You don't get to "stipulate" anything. You can certainly offer your definition of phase to support your position. You don't get to foreclose on the definition though.

 

[mivey]

You need to check your understanding of stipulate. You don't get to "stipulate" anything. You can certainly offer your definition of phase to support your position. You don't get to foreclose on the definition though.

I will add stipulations as many and as often as I please.

 

[mivey]

I will add stipulations as many and as often as I please.

I guess the "beef" is you don't want me to force you to agree to anything. It was intended to be a list of stipulations and you could accept or not. But my answers are not going to be binding until you adopt those stipulations.

So, rbalex:

Given that a definition of phase has not been specified, I will make the stipulation that my technically correct definition still stands.

Did you propose a different definition or did you not mean to imply that my definition was fine? After all, hearing no objection...

I will further stipulate that we are not considering the number of phases present in the circuit due to currents.

Did you propose that we also consider the phase of load currents?

I might as well stipulate that the voltage magnitudes on the secondary are all equal for the voltages we are considering.

Did your diagram intend to open up the discussion to the phase order of systems of voltages where multiple voiltage magnitudes are present?

Thanks for the lesson in legalese.

 

[pfalcon]

With that, we can have voltages with a phase of (ωt+φ₀) and voltages with a phase of (ωt+φ₀+180?).

As the distinction between (ωt+φ₀) and (ωt+φ₀+180?) is nothing more than changing your leads from, for example, BD to DB and declaring it a different phase; I can only agree to it as a "pragmatic" interpretation of phase that will generate 30+ based on where you tap and which direction you place your taps.

 

[Smart $]

...

Assume the applied primary voltage is characterized by the general function V(t)= A sin(ωt+φ₀), where A, ω and φ₀are constants. ...

Ok, a sinusodial input on the primary.

...

With that, we can have voltages with a phase of (ωt+φ₀) and voltages with a phase of (ωt+φ₀+180?). So, using the technically correct definition for phase and the stipulations I noted, we can have up to two phases present at any given point in time.

I've been trying to stay out of this part of the discussion but find I no longer can, at least for one post :blink:

Given the reference is the primary voltage, it follows that secondary voltages be measured in the same manner. You can only have secondary voltages that I highlighted red. While you can measure voltages that I highlighted blue, they are still the same voltages... only polarity inverted. There's only 15 possible voltages at any instant, not thirty. Isn't voltage defined as the potential between two points? Flopping points to do the measuring doesn't give you a second voltage. It's still the same voltage... you are just perceiving it differently. And as I said the reference is primary voltage, if you flop leads to measure the secondary voltages, you also have to flop your reference leads. So technically, your reference timing shifted a half-cycle on the primary and you end up with secondary voltages as I highlighted red... :thumbsup:

However, it is still called a single-phase transformer.

Rightly so. :slaphead:

OK, I'm done saying all I have to say on the matter. Rhetoric may continue as normal...

 

[mivey]

Given the reference is the primary voltage, it follows that secondary voltages be measured in the same manner.

Just an opinion.

There's only 15 possible voltages at any instant, not thirty.

I did not bother to count as I suspect it is really far removed from what rbalex wants to discuss. I just used the figure pfalcon threw out there.

 

[mivey]

As the distinction between (ωt+φ₀) and (ωt+φ₀+180?) is nothing more than changing your leads from, for example, BD to DB and declaring it a different phase; I can only agree to it as a "pragmatic" interpretation of phase that will generate 30+ based on where you tap and which direction you place your taps.

Any voltage reference frame is a choice, not a given.

 

[rbalex]

I will add stipulations as many and as often as I please.

Yes - I'm well aware of that. It's one more thing you don't do properly. What would be proper is to cite a source for your definition rather than assuming everyone agrees with it.

 

[pfalcon]

Given the reference is the primary voltage, it follows that secondary voltages be measured in the same manner. You can only have secondary voltages that I highlighted red. While you can measure voltages that I highlighted blue, they are still the same voltages... only polarity inverted. There's only 15 possible voltages at any instant, not thirty. Isn't voltage defined as the potential between two points? Flopping points to do the measuring doesn't give you a second voltage. It's still the same voltage... you are just perceiving it differently. And as I said the reference is primary voltage, if you flop leads to measure the secondary voltages, you also have to flop your reference leads. So technically, your reference timing shifted a half-cycle on the primary and you end up with secondary voltages as I highlighted red... :thumbsup:

:thumbsup:

Same situation applies to the single center tap ANB: 1 primary (240V); 2 secondary AN, NB (120V); and three BA, BN, NA (blue) appear by flopping leads without correcting reference.

 

[rbalex]

I guess the "beef" is you don't want me to force you to agree to anything. It was intended to be a list of stipulations and you could accept or not. But my answers are not going to be binding until you adopt those stipulations.

Your'e not forcing me - you're trying to force everyone

Did you propose a different definition or did you not mean to imply that my definition was fine? After all, hearing no objection...

Nope - I left the definition open. You can certainly use yours to support your position. Just no one has to accept it at the moment; which is basically what "stipulate" means in this context.

Did you propose that we also consider the phase of load currents?

Nope, They're irrelevant in my opinion for the time being.

Did your diagram intend to open up the discussion to the phase order of systems of voltages where multiple voiltage magnitudes are present?

No - but if you want to chase another rabbit - start your own thread.

Thanks for the lesson in legalese.

You're welcome.

 

[pfalcon]

Just an opinion.

An opinion expressing that you should be consistent in how you use a reference frame.

I did not bother to count as I suspect it is really far removed from what rbalex wants to discuss. I just used the figure pfalcon threw out there.

15 red: AB, AC, AD, AE, AF, BC, BD, BE, BF, CD, CE, CF, DE, DF, EF.
15 blue: FE, FD, FC, FB, FA, ED, EC, EB, EA, DC, DB, DA, CB, CA, BA.
Smart$ pointed out that Red & Blue are simply reversals of each other. Useful but not really unique.

AF or FA depending on your preference is the secondary coil voltage. The others are created as classic voltage divider and lead reversal voltages.

Any voltage reference frame is a choice, not a given.

But as Smart$ points out, the waveform is only different because you reversed how you measured one axis of your 2D reference frame but were inconsistent by not reversing the second axis to match.

 

[rbalex]

BTW I'm trying to see if I can alter the pole to allow changing votes. Remember, I didn't ask what the transformer was, I asked "how many phases"?
Apparently wiping it out is the best I can do - I truly apologize.

 

[Smart $]

BTW I'm trying to see if I can alter the pole to allow changing votes. Remember, I didn't ask what the transformer was, I asked "how many phases"?

Had me wondering there for a split second hmy:

For the record, I voted 0 initially because you didn't specify any primary input. It would still be zero if you had spec'd a DC voltage :blink:

I see the POLL changed and I revoted 1...

 

[mivey]

Yes - I'm well aware of that. It's one more thing you don't do properly. What would be proper is to cite a source for your definition rather than assuming everyone agrees with it.

I did not assume everyone agreed with it. It was the definition I used to go along with my response. My improper use of the word stipulation did not reflect my intent.

 

[mivey]

BTW I'm trying to see if I can alter the pole to allow changing votes. Remember, I didn't ask what the transformer was, I asked "how many phases"?
Apparently wiping it out is the best I can do - I truly apologize.

Sticking with (NOT stipulating ) my previous definition of phase, and other clarifications, including that I am considering the secondary voltages and that voltage is a relative measurement:
Using one of the reference frame options: one.
Using a different one of the reference frame options: two

I also favor charlie b's answer because the term "phase" has not been defined by the OP so the question is really too open-ended.