Data partitioning
The major challenges in integrating an asset registry with a GIS-based network model
are:
- The database design to define the partitioning of data between long and short transaction data types
- The analysis of data to determine the business process ownership to ensure that no conflicts exist between updates to the long and short transaction databases
To accomplish this, the concept of a facility will be separated from that of an asset. A
facility is something owned and maintained in the spatial, long transaction database,
and is part of an engineering model of the distribution (and/or transmission) assets of a
utility. An asset is a record of a physical piece of equipment, whether or not it is
performing a function at a specific location or at a specific time. This is illustrated by the
following example of an electric distribution transformer as shown in Figure 1
"Bank/Device Model." These are typically three-phase devices that are installed at some
point on the primary electric network to step down voltage to secondary level to provide
service directly to individual customers. Based on the primary voltage, secondary
voltage, and desired load capacity (as a function of the number and type of services),
an engineer defines the engineering characteristics common to the installation as a
whole and to the individual phases where these values may differ. The engineer has
defined a bank facility and up to three device facilities. At the time of a design, the
designer generally has no specific requirement as to manufacturer, nor has any idea as
to asset-specific information such as serial number, date of purchase, or cost of
purchase. The specific asset to be used to actually perform the function of the device
slot is established at a later time. When construction and installation work is actually
completed, as-built field reporting will provide that information. At this time, a
relationship is constructed in the database between the physical item of equipment (the
asset) and where it is performing its function (the phase of a particular bank).
Figure 1 - Bank/Device Model
The particular transformers actually used to perform the function must meet certain
engineering characteristics for that class of transformers. When a design is developed,
a transformer of a particular class is selected. A physical transformer to actually perform
the function would have a matching set of characteristics. These are organized into
specification tables that provide a look-up table of legal combinations of engineering
characteristics of physical equipment items. When specific items of equipment (assets)
are actually installed in the field, the physical asset's engineering characteristics should
match those of the specific item (or change specific to specifications) defined for the
particular facility.
It is similar for conductors, where within an electric segment is a facility with a particular
function, with individual conductors for each phase, that reference particular standard
engineering specifications. The Figure 1 example presents a situation where individual
conductors are not treated as assets, and as such do not have records within an asset
database.
The GIS provides capabilities to manage the connectivity of linear and point facilities
through a configurable set of rules that defines how facilities connect to each other.
Connectivity rules provide definition in terms of what facilities can or cannot connect to
others, where they can connect, and what actions are to be performed when they
connect. For example, a transformer connects to a segment at any point along its length
without breaking the segment. However, a switch may only connect to the end of a
segment, or it must break a segment if it is connected at any point other than its end
point. Similarly, additional rules may be applied, such as conductors at the same
voltage level are allowed to connect, but are not allowed to connect if they are at
different voltage levels.
Figure 1 describes the relationship of an asset to a facility in terms of the asset being
installed at a facility to perform a function. However, in reality, the relationship is more
complex than that. Assets are installed and removed, and often installed at another
facility location at some other time. Asset management applications typically require
knowledge of the entire history of an asset, not just where the asset is currently
installed.
Figure 2 - Asset Event History
