Electric UN Foundation - Junction Object Question

[MobiusSnake]

Hi all,

I'm new to the Electric UN Foundation model, and I've been going through the Naperville data to familiarize myself with it.

One thing I've noticed is that there are a lot of Electric Devices than contain similarly-named non-spatial junction objects.  For example, transformer devices containing a single transformer junction object, fuse devices containing a single fuse junction object, and circuit breaker devices containing a single circuit breaker junction object.

The junction objects don't seem to have any connectivity associations to other devices, junctions, or non-spatial objects.  They also don't seem to contain any other non-spatial objects - I thought maybe they might contain multiple assets within them, but that doesn't seem to be the case.  Since these non-spatial objects don't seem to connect to anything else, or contain anything else, what is their purpose?  As far as I can tell they just seem to be non-spatial copies of the devices.

Thanks!

[LongDinh]

Hi @MobiusSnake,

Junctions are used to model the network granularity and can play a part in the connectivity model.

Representing individual connection points/terminals as spatial features is problematic as it becomes more difficult to work with stacked geometry and devalues the network's spatial representation. We can use a junction store/represent the network features instead so that lower level details are not lost.

An example of their use may include representing a number of connection points/terminals for your transformer device as a junction object. The transformer should not have n number of point geometries, but simply a relationship to a non-spatial object, a junction, containing its connection/terminal path details.

But, at the end of the day, it is just another data model so its really up to the application of the model on whether junction objects are required.

Hope this helps!

[MobiusSnake]

Thanks for that, I'm still a bit fuzzy on their purpose within the Naperville data specifically, however.

I'm more familiar with the Communications model, where a device like a splice enclosure would contain a number of non-spatial junctions, with J:J connectivity and containment between them, representing things like splice points contained on a tray, or switch ports connected to patch panel ports.  Some of these junctions also connect to non-spatial edge objects (like fiber strands) contained within cable features.  That all makes sense to me and jives with your description of the role non-spatial junctions play, but what I'm failing to see is what purpose they have when there's no connectivity or containment between them, which is what I'm seeing in the electrical data.

I could understand it if the non-spatial junction was of a different asset type than the containing device as well, I could imagine how that would add value from an asset management perspective even without any further associations, but as far as I can tell all of the non-spatial junctions in the Naperville data are contained by devices with the same asset type.

Maybe I'm overthinking this and the junctions in the Naperville data don't add any value, and they're simply there to demonstrate how non-spatial junctions can be contained within devices?

[MikeGoggin]

Hi @MobiusSnake, 

Your observations are spot on.  I can tell you the intent Esri is providing in the Naperville UN configuration for electric is to have those junction objects part of the connectivity model using connectivity associations.  The devices become containers for the junction objects so something is on the map, a requirement for dirty areas, but the devices themselves don't drive the connectivity, they are passthroughs.  The junction objects are the operable devices.  The issue with the Naperville dataset is the data itself - if you are going to experiment with it you will find you need to do some cleanup work including reconfiguring the connectivity of those devices and junction objects.  The rules are there to support it.

[RobertKrisher · Accepted solution]

I agree that the majority of the junction objects may seem redundant but will try to explain how this model is typically implemented.

This sort of bank/unit type modeling is a byproduct of an electrical system that can have anywhere from 1-3 different devices (or wires) at any given location.

As an example, a location serving three phases of electricity could have a single three-phase transformer (junction object), three single-phase transformers (three junction objects), or even two single-phase transformers that are wired in a particular way (two junction objects). Each of these objects has its own unique serial number and attributes, so we need to model them in the GIS, but because they are all connected at a single location it is easiest to place a device there and create the equipment as junction objects. An alternative would be to draw each piece of equipment as its own device, contain them in an assembly, and attach them to the lines using junctions (spatial junctions). You can find examples of all of these approaches in Naperville if you look close enough.

Placing a device at the physical location, then creating non-spatial objects that corresponds to the actual installed equipment gives you a degree of freedom to handle this. There can also be some benefits to this approach when it comes to integrating with certain asset management systems that require all equipment to exist at a location (device) but also have information about the individual assets (junction objects).

[MobiusSnake]

Thanks Robert, from an asset management perspective - assuming multiple junction objects per device - that certainly makes sense.  This was my assumption for why three-phase conductors have four non-spatial edge objects contained within them (with no connectivity associations), since it allows each of the four separate conductors to have their own attributes, e.g. install date if one had to be replaced individually.  What was throwing me off with the devices and junction objects is that all of the data I was bringing up in Naperville is one junction per device, without any additional attribution like serial numbers and things like that.