ArcFM Feeder Manager typically considers a “source” to be a substation circuit breaker. In some cases one might also consider as sources step-down transformers (either inside or outside of the substation). One might also choose to implement “Extended feeder Manager” and define generation facilities as sources. But for this study we’re going to consider substation circuit breakers (or circuit reclosers) as Feeder Manager sources. We’re also going to consider the case that the Geodatabase includes substation equipment upstream of the circuit breaker not only present as features in the database, but also as features participating in the geometric network.
Benefits of housing substation equipment in the Geodatabase along with distribution (and possibly transmission) equipment include:
- It can be mapped and accounted for using similar data maintenance processes used throughout the organization
- Similar data validation processes applied for distribution (and transmission) can be applied to substation equipment – including connectivity
- It can be provided to external applications, such as OMS or DMS, using similar interface processes
- If current carrying substation equipment is present in the geometric network, then traces can determine connectivity from substation transformer to the customer
If substation equipment above the circuit breaker is included in the geometric network and we’re not implementing extended Feeder Manager then it is vital that equipment upstream of the breaker be defined as Feeder Manager non-traceable. There is nothing in the circuit breaker feature definition to inform it of what is “upstream” and what is “downstream.” Left fully connected, all feeders from the substation would be connected to one another and all downstream equipment would be multi-fed.
Two ways present themselves to avoid this condition:
- Leave a space between the circuit breaker feature and the immediately upstream bus bar segment (below left)
- Assign the busbar segment immediately upstream of the breaker a value of “true” for the Feeder Manager field [FdrMgrNonTraceable] (below right).
The second approach provides the advantage that core ArcGIS tracing initiated upstream of the breaker will continue through it to all downstream equipment, while Feeder Manager traces will stop at the breaker without multi-feeds.
So given this direction, how do we go about selecting just those substation busbar “upstream” of the breaker, and not those downstream of it, to assign the [FdrMgrNonTraceable] value? Clearly we can’t use Feeder Manager tracing. This is territory outside the knowledge of Feeder Manager.
If there are a small number of substations in the system, then the most straightforward process is probably to manually inspect each station. Select the busbar just upstream of each break and set the [FdrMgrNonTraceable] value. However, if there are many substations the manual approach could be tedious an error prone.
The alternative is to use core ArcGIS tracing functions – those found on the Utility Network Analysis toolbar — to select busbar between the power transformer and circuit break and set values for [FdrMgrNonTraceable].
The steps will vary based on the types of equipment modeled inside the substation, but in general we’ll want to set “flags” at power transformers as sources, then un-select features we want to use as barriers and initiate a trace on selected substation features. While there are multiple ways to accomplish this, its safest to limit any particular trace to the contents of a given substation so that we can avoid a case where a trace leaks beyond the substation boundary and we end up trying to process features in the distribution system.
Here are specific steps making some assumptions about the target data model:
- Select all closed switches in the substation. These need to be traced.
- Purposefully leave all open switches un-selected. These will form barriers to the trace.
- Select all bus bars in the substation. The specific method will depend on where your bus bar is stored and how it’s attributed. If you’re confident that all bus bar is enclosed inside a substation fence polygon, then you can use that boundary for a spatial search.
- Select any regulators or miscellaneous network features present inside the substation. Remember that if these are left un-selected they will be treated as barriers.
- Purposefully leave all circuit breakers un-selected. We want these to be barriers.
- Select power transformers in the substation and create “flags” at each of these junctions.
- Initiate a trace on selected features.
- The result will be all equipment between the breaker(s) and the power transformer(s). At this point we can accomplish our goal by setting the [FdrMgrNonTraceable] field for all selected bus bar features to “true.”
- If we want to limit our updates to only those bus bars most immediately upstream from the circuit breaker we can add a step to perform a step to spatially select from the current selection set of bus bar those that fall within a very small search tolerance of a circuit breaker. Remember that at this point only busbar upstream of the breaker will be selected, so selecting from only those features already in the selection set will return only the upstream busbar and not the downstream.
At the end, we’ll have substation equipment available for all ArcGIS traces and distribution equipment downstream of the circuit breaker available for Feeder Manager tracing.