CUs in Designer's GIS Environment

This topic applies to Designer versions 10.0.2 and earlier.

In the case of symbolized CUs, it is necessary to assign a feature class to the CU so that Designer will be able to create an instance of the feature class when the CU is added to the design.

There are also cases in which a single map feature might represent a collection of CUs. Consider the example of the transformer bank given in the discussion of non-symbolized CUs: One feature represents a bank of several transformer units. For example, a three-phase transformer bank can have three related units, each representing a phase of current. Another case would be where a feature would be represented by a CU, but would also use additional non-GIS CUs that provide work management information for the feature. For example, the addition of a gas valve not only involves a CU for the equipment installed, but also might require CUs for asphalt removal, digging, health and safety equipment, etc.

To facilitate the assignment of multiple CUs to one feature class, an additional layer has been added to the design as it exists in Designer. This added object is called the MMGISUnit or GIS Unit (GU). A GU is simply an object that contains a reference to an object class and subtype with references to one or more CU objects. Figure 1 shows the relationships that can exist between the CU and GU objects.

Figure 1, CU/GU relationships

Examples of CU Types

The types of CUs (symbolized, non-symbolized GIS, and non-GIS) can be represented by various GU/CU configurations depending on the way the Designer geodatabase is modeled. The following examples illustrate some typical cases.

Symbolized CU

Here, a CU representing a Class 3, 30 foot wood pole is associated to a GU that specifies the 'Wood Power Pole' subtype of the 'SupportStructure' feature class.

Figure 2, symbolized CU structure

Non-Symbolized GIS CU

Here, the GU specifies that Designer create a row in the JointUseAttachment table, with the attributes of the row specified by the CU defining attributes on the CU.

Figure 2, non-symbolized CU structure

This would create a pole feature and add an attachment record to the design and geodatabase.

Non-GIS CU

A GU is not necessary, since neither a feature nor row is added to the geodatabase. Asphalt removal is not stored in the GIS, but is important to the WMS. In a design scenario, a CU can be placed under an existing GU, a Work Location or under the Design node itself.

Figure 3, non-GIS CU structure

CU Types Combined in Design Scenario

The above examples could be combined together at a work location in the design scenario as shown in Figure 4.

Alternatively, the asphalt removal CU could be placed directly under the GU that represents the pole feature to be added. This is shown by the dashed line.

Figure 4, various CU object relationships

Modeling Banked Features

In many data models, you will find features modeled as "banks." A banked feature is one that is represented by a single feature, but is actually composed of one to many separate parts. These constituent parts are stored as object rows in the geodatabase which are related to the feature via a relationship class. These related rows are often referred to as "units."

In electric models, overhead transformers are often modeled this way. The transformer point feature represents what is often called the “transformer bank” that is comprised of one to three "transformer units," depending on the phase configuration of the bank. Figure 5 shows how the CU structure for a three-phase overhead transformer might look.

In gas models, a good example would be a meter setting (or meter station). In the GIS, a meter setting is modeled as a point feature, but is actually comprised of one or more separate meters. In other words, the meter setting is a bank of meters. Like the transformer units, the meters are modeled as related units to the meter setting feature.

Figure 5, banked feature CU