ArcFM Feeder Subsource Level: This autoupdater populates the FeederLevel field of the related CircuitSourceID row for any junction whose Subsource value changes from No to Yes, as well as for any newly created junction that has a Subsource value of Yes. If the FeederLevel value is derived from any features other than the subsidiary junction itself (for example, if the OperatingVoltage value of neighboring conductors helps determine the FeederLevel value), then the Level AU should be designed to respond to OnUpdate events of those other features as well. You may replace this autoupdater with a custom AU.

This out-of-the-box autoupdater computes FeederLevel as a function of the operating voltage values encoded in the MMElectrciTraceWeight field of the edges attached to the subsidiary source junction. This implementation is intended to work well with a data design that uses a subsidiary source to mark the source of each feeder at a given voltage level. A typical arrangement of this sort has a set of subsidiary sources immediately downstream of a transformer and connected to it by substation bus work. Each of the subsidiary sources corresponds to a distinct feeder at the transformer's secondary voltage level. In this design, the transformer itself may optionally be considered a subsidiary source that is one level higher than its immediate "child" sources.

The purpose of designating FeederLevel for subsidiary sources is primarily to provide an extra cue for electric tracing. It enables a downstream trace, for example, to detect when it is about to pass the "wrong way" through a subsidiary source and to stop itself from doing so. The "wrong way" scenario can happen when the tracing enters a mesh area that is powered via several subsidiary sources simultaneously (e.g., a network secondary circuit). Armed with the FeederLevel information, the trace can refuse to exit the mesh by way of a different subsidiary source other than the one through which it entered, and thus stop itself from chasing on up to higher voltage levels in the mistaken belief that it is still headed in the "downstream" direction.