A Dynamic Electric Utility GIS Database

Introduction

Electric Component Discovery

                      TABLE  I
        Electrical Components and Attributes

   COMPONENT NAME          COMPONENT NAME
     Attribute Names         Attribute Names

  CONDUCTOR OH* PRIMARY   CONDUCTOR UG* PRIMARY
    Circuit ID              Circuit ID
    Conductor Type          Conductor Type
    Date Installed          Cable Number
    Feeder                  Date Installed
    Impedance               Feeder
    Length                  Impedance
    Operating Voltage       Insulation Thickness
    Phase                   Length
    Size                    Manufacturer
    Work Order Number       Reel Number
                            Size
                            Work Order Number

  LIGHT                   POLE
    Billing Code            Class
    Customer Account        Date Manufactured
    Date De-Energized       Framing Type
    Date Energized          GRID #
    Date Installed          Height
    GRID Number             Material Type
    Lamp Type               Orig. Ground Level Circ.
    Lamp Watts              Original Treatment Type
    Luminaire type          Ownership
    Manufacturer            Pole Number
    Map Number              Species
    Owner                   U-Map Number
    Job Number              Work Order Number

  SWITCH                  TRANSFORMER
    Address/Location        Circuit ID
    Circuit ID              Company ID
    Company Number          Date Installed
    Date Installed          Date Manufactured
    GRID Number             GRID Number
    Initial Cost            Impedances
    Manufacturer            KVA
    Model Number            Manufacturer
    Serial Number           PCB Content
    Switch Number           Primary Voltage
    Voltage Rating          Secondary Voltage
    Work Order Number       Serial Number
                            Work Order Number

   * (OH = OverHead, UG = UnderGround)

The resulting lists showed that many of the components had some of the same attributes (i.e., Circuit ID, GRID Number, Work Order Number, etc.). Also, some of the component attributes had different names but were the same (i.e., Job Number and Work Order Number.).

AM/FM Systems

Information Engineering

Figure 1   Distribution OH Structure ERD

Figure 2   Distribution Electric ERD

ArcInfo

Our first AM/FM/GIS database design with ArcInfo consisted of almost one layer per entity. However, this design did not work very well. ArcInfo was slow switching between layers during editing. Some users stated that they could draw maps faster manually.

The second design put all of the electrical distribution entities into one layer. This solved the editing performance problem but created a data problem. This problem was solved by eliminating all of the attributes that did not occur on maps and generically naming attributes so they could be used to handle data for whatever entity was being recorded. This design was used successfully to do map conversion.

Integration

Our first AM/FM ERDs revealed many duplicate connection points to other systems (i.e., Work Order Number attribute occurred in each entity). This was not desirable. Multiple interface points for the same data would make interface application development between them complex. We wanted a simple interface for each corporate database.

During the electrical component discovery process, one user group provided us with the name of the interface point. But it was not realized and used until four years later. The user group was Plant Accounting of the Property Records department. The Utility Plant interface point was born. Figure 3 shows Utility Plant as the hub with other corporate databases around it and with one interface each.

Figure 3   Utility Plant Integration

Utility Plant ERD

Figure 4   First Utility Plant ERD

Figure 5   Composite UPI entity Model

Pilot Implementation

The Pilot was a success, but it did show some weaknesses with the model in interfacing with ArcInfo. Some UPI occurrences were not shown graphically (i.e., on a map), but were related to those that were. A new entity was needed that would provide a one-to-one correspondence to each graphic or GIS Object in ArcInfo.

Dynamic Database

Figure 6   Dynamic Database Design

The database is made dynamic by having tables that contain rules, descriptive information and list of values which are used by the applications to control what can be done. Each electrical component type that is shown by a graphic is defined by a record in the GISO Types table. If a new electrical component type is needed it is just added to the GISO Types table. There are other control tables that are related to the GISO Types table. They define what graphic manipulations can be done, how annotation text is generated and placed, what data is required, what UPI Types can be attached to a GISO Type, etc.

The graphic is completely describe by the GISO data, the attached UPI type data and UPIs are described by a reference to a Plant Standard Material occurrence. Figure 7 shows a GISO, attached UPIÕs and each UPIs assigned material.

Figure 7   GISO UPI Material Relationship

Summary