Sorta of a brainer teaser

[ronaldrc]

Rattus

When Larry and I where talking about the A,B and C coils being on different cores or the same thing since the magnetic flux is imbodied around the coil more or less I agree it is more or less like three different transformers.

But, I also think there would be enough flux flow across the iron for there to be a voltage generated in the other poles even though it would be small.

And on the 416 primaries I think the flux would be the same rather the neutral was hooked or not. Because it is 208 source across the two coils with or without it.

 

[rattus]

Rattus

And on the 416 primaries I think the flux would be the same rather the neutral was hooked or not. Because it is 208 source across the two coils with or without it.

No so Ronald. In the one case you have 120V across each secondary. In the other you have 104V across each secondary. The flux in either case is proportional to these voltages.

 

[ronaldrc]

No so Ronald. In the one case you have 120V across each secondary. In the other you have 104V across each secondary. The flux in either case is proportional to these voltages.

Rattus

I was wrong it is 104 without the neutral.There would be a 16 volt difference with out the neutral if fed with 208.

 

[jghrist]

There is a big difference between having X0 connected to the supply neutral or not.

When X0 is connected, 120V will be impressed across the connected windings, 120? apart. The transformer will act like an open wye - open delta transformer as outlined in my Post #80.

When X0 is not connected, the 208V input will be divided across the two connected windings. Each will have 104V, but of opposite polarity. The two corresponding 480V windings will have 416V across them, 180? apart. The third winding will have no voltage across it. This connection will not operate as an autotransformer because the windings are not on a common core.

 

[LarryFine]

The 480V primary, without the winding associated with the unconnected secondary, is an open delta connection.

Now, consider the third delta winding to be connected across the open delta - 480V. This 480V induces 120V in the unconnected 120V winding.

When X0 is connected, 120V will be impressed across the connected windings, 120? apart. The transformer will act like an open wye - open delta transformer as outlined in my Post #80.

I totally missed that the high-voltage side of this transformer was connected Delta. I was imagining Y-Y. That does make a difference.

With the neutral connected to the source, I agree that the third side of the HV Delta would induce a voltage on the third LV winding.

 

[rattus]

That's OK Larry:

That's OK Larry:

I totally missed that the high-voltage side of this transformer was connected Delta. I was imagining Y-Y. That does make a difference.

With the neutral connected to the source, I agree that the third side of the HV Delta would induce a voltage on the third LV winding.

That's OK Larry; I made a mistake once--thought I was wrong!

Made another mistake though--thought I was right!