Overhead Single Phased Delta Transformer - Also called Dual Voltage Transformer

[MikeMillerGIS]

@jalsup

[MichaelZeiler]

@jalsup, I made a number of changes from your drawing:

• changed pad to pole (all OH)
• changed containee features in assembly to be consistent with other models

One thing that jumps out is that we have a loop in this model. How do we resolve that?

Another thing that deserves discussion: is this pattern correct of including taps inside the assembly and attachment and line end outside the assembly?

[jalsup]

Hi Mike. thanks for catching my errors. Since we are using explicit connectivity, there is no loop, but we will check to be sure.
We have another version of this same transformer, but with a different terminal configuration. H1, H2, X1,X2 and X3. If you could take this diagram and copy it to a new version and then modify the new one it to use the more detailed terminals, we can show both tomorrow.

[MikeMillerGIS]

@MichaelZeiler I think we should color code or change the shap the terminal circles when directional. This would help. Circles Bi Directional, triangles with point denoting direction

[MichaelZeiler]

Overhead three phase wye transformer with riser.pdf

Here's the PDF. Substantially the same, just some cleanup.

Today I'm focused on getting ready for tomorrow's meeting. After tomorrow's meeting, I'll install Tortoise Git and start pushing my content to git.

[MichaelZeiler]

Ok, I'll work on a variation of the diagram with five terminals on the transformer. And I forgot about directional terminals preventing loops. I'll think about how best to depict that. I have an idea...

[MichaelZeiler]

How about this?

[jalsup]

so, both terminal configuraitons are directional. Is this supposed to represent the H1,H2,X1,X2,X3 terminal configuration? If so, we are missing the terminals on the low side.

[MichaelZeiler]

@jalsup For the five-terminal transformer with H1, H2, x1, x2, x3, can you tell me what the terminal path configuration is? I've been googling for wiring diagrams on this and can't find any.

I'll add a little graphic to the side of this feature showing the terminal path configuration as I did earlier for bypass switches

[MichaelZeiler]

John, I thought you wanted to show both two-terminal and five-terminal cases. For two-terminal, I thought that one triangle on top would be enough to show direciton. For five terminal, we need a little graphic showing the path configuration

[MichaelZeiler]

I did this for bypass switches and I propose something similar wehre there is an auxiliary graphic showing path configurations.

Question: is there one terminal path configuration for 120-volt and another for 240-volts?

[MikeMillerGIS]

We might have to draw the line at terminal config or use a pop out. We also need the downstream terminals shown as directional

[MichaelZeiler]

Is this the relevant wiring diagram? Looks like 8 terminals.

This will trigger Erik for hours, we better get this right. Maybe we should stick to simpler examples

[jalsup]

no, those are for three phase transformers, single unit, not a bank of three.

[MichaelZeiler]

I'm puzzling over the terminal path configuration. It's confusing because there are no direct connection between the high-side and low-side terminals, but a electromagnetic field between the two windings.

If we have 5 terminals, we must have two terminal path configurations. So what are they?

[MichaelZeiler]

Another thing to consider is that x1, x2, x3 connect to the three wires in triplex, -120 volt, 0 volt, 120 volts. This is not phasing. So do we simply connect x1, x2, x3 to a line end of triplex?

If so, what does that mean? We would never do a trace to the separate three wires in triplex, doesn't make sense. So does a 5 terminal transformer model really make sense in a GIS?

Unless we get clarity real soon, we don't want to go down this path with Erik tomorrow

[jalsup]

This same transformer (all the terminals) could be used in a bank, where the order of connections of X1, X2 and X3 become important for phase shifting. Also, in the single phase configuration, you will frequently connect street lights to only X1 or X3 (and always X2) to obtain 120 volts. Also, I disagree with your comment about X1 being -120v and X3 being +120v. That would only occur every 1/60 of a second. And, they reverse every 1/120 of a second, hence the term "alternating". when X1 is connected to X3, there is a difference of 240v at the peaks/lows of the phase curve. But, this is getting way too deep for these diagrams!

[MichaelZeiler]

So what are the terminal path configurations for a five terminal transformer? If we show 5 terminals, we have to show that.

[MichaelZeiler]

I remembered that H2 is connected to the neutral wire. So that simplifies the path configurations, is it this?

[jalsup]

H2 is only connected to the Neutral if you are connecting to a "Wye" circuit. If you are using delta, H1 and H2 will be connected to two different energized conductors of different phases.

[MichaelZeiler]

Ok, I see that one phase is connected to H1 and the other to H2 in a delta connection. And x2 is connected to the ground in triplex.

But what are the terminal path configurations for the two Vac outputs?

[jalsup]

for paths in the case where we model each terminal, the only valid paths for the software to work are 1) All 2) H1-X1, H2-X3 neither of which are electrically correct, but I would just go with All

[MichaelZeiler]

This can't be right, but I'm posting this to advance the discussion. And we definitely should not show this tomorrow.

I just can't grok how terminal paths work across the electromagnetic field between two windings in a transformer. There are no direct connections but a kind of blending of phase shifts.

Another issue is that if we go down the path of 5 terminals, then we need to also model the individual wires in duplex/triplex/quadraplex.

From a GIS tracing/analysis perspective, I also don't see the benefit of a five-terminal model.

[jalsup]

I agree, the entire terminal concept is strange to me in an electromagnetic field. I have not found a completing reason to model individual terminals in a transformer beyond High and Low. All Analysis software I have reviewed only takes a transformer configuration Dd0, Yy0, etc. I can not find where electrically H1 connected to A phase and H2 connected to B phase is any different than H1 connected to B phase and H2 connected to A phase. I might be wrong, but I can't seem to find a formula that cares for a single phase. Three phase is a little different, but again, that can be determined by attributes of the assembly. Yes, I would prefer not to show this example yet. The simple terminal model will do for tomorrow.

[MichaelZeiler]

Ok, so I'll deliver clean PDFs to you in the next couple of hours for the following:

• unfused riser tap (2 phases)
• single phase dual voltage transformer (two terminals)
• three phase wye transformer with riser and streetlight

[MichaelZeiler]

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[MichaelZeiler]

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