Overhead Three Phase Wye/Delta

[MikeMillerGIS]

An example of a distribution transformer delivering three phase power using three overhead single phase wye transformer units

[MichaelZeiler]

@jalsup Here is a test incorporating changes from the Wednesday meeting, plus two variations: a wye transformer bank with a riser and streetlight (as before) and a variation which is a delta transformer bank with a mix of 1ph and 3ph OH services. My thinking is this: we can't do every conceivable variation, but we can do variations within variations (like mixing up OH/UG services and wye/delta) that collectively cover the main cases. What do you think?

[MichaelZeiler]

Also, for a working procedure @MikeMillerGIS , should I post every PDF for pull requests as I soon as I create them, or post JPGs of the PDF in an issue until John says it's good, then submit the PDF for pull request?

[MikeMillerGIS]

Either is fine, would be good to get the PDF in and then we can use the issue to work through changes. The jpg in the issue is easy and fast to review

[jalsup]

I like the mix of low voltage lines. However, the asset type names are wrong. We just use duplex, triplex and quadraplex. So, in this case you would be using Asset Group:Low Voltage, Asset Types:Duplex (street lights, half phase), Triplex (standard service, single phase) and Quadraplex (all three low voltage phases). Also, the Line End feature needs to be associated with the Pole.

One last consideration for editing. Should the Low Voltage lines attach to the terminal or should we use a line end as we do everywhere else? This would maintain the association to the pole, and

[MichaelZeiler]

John, in prior conversation with Erik/Tom, they seem to prefer that single phase secondaries be directly connected to the low terminal of a transformer. In the delta xfmr bank above, we need the line end because we have to establish three connectivity associations to the three phase low voltage line.

Also, to reduce map clutter and an extra attachment association, how about moving the line end inside the assembly like the taps?

I'll review/fix the secondary AG/AT

[jalsup]

if we do, you loose the attachment to the pole. We should use line ends, also for editing consistency.

[MichaelZeiler]

Line ends for single phase secondaries too?

[jalsup]

all low voltage lines.

[MichaelZeiler]

Like this?

[jalsup]

correct. Next, we need to think about how to show the relationship from the Line Ends to the Crossarm table.

[jalsup]

In the three phase wye diagram, we should remove the line from the streetlight to the transformer and replace it instead with a connectivity association. Since the light is on the same pole as the transformer, there is no need for drawing a wire, as it very short. The other option is to instead create a Low Voltage "Line End" feature that the low voltage line connects to. This would also have a connectivity association to the Low terminal on the transformer and have a connectivity association to the pole and also have a related record in the crossarm table (how ever we decide how to denote that).

[MichaelZeiler]

John, is this what you meant in your reply to Erik's email?

Also, will we retain all three line ends on the secondary side?

[jalsup]

One issue left, you typically make one transformer larger than the other and both streetlights would be tied to that one. So in this diagram you should move both streetlight connections to one transformer.

[MichaelZeiler]

I'm confused, what streetlights? I placed one streetlight in the wye-wye variation, are you referring to that?

In this case, wye-delta, are the connectivity associations between the fuses and transformers correct?

[jalsup]

I need a bigger monitor. ok, now I can see they are two triplex lines and one quadraplex. we may want to add a note about what these are serving. For example, add a note about the triplex serving non-commercial load, i.e. residential as an example.
Also, the connections from the fuses to the transformers is correct now. For clarity, maybe we should place the low voltage phase identifier by the lines "a" on the left, "abc" for the center and "c" for the right. Just a thought.

[MichaelZeiler]

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