Every device in the field can be physically connected to one or more lines. When these connection points are explicitly modeled in the GIS we refer to them as terminals. The utility network can model multiple, distinct connections to a device or junction object using terminals. These may be in the form of bushings on a transformer, the inlet/outlet of a regulator, or the ports on a manifold, for example. Terminals are an optional configuration for devices and junction objects and are only required for a feature to act as a subnetwork controller.
To learn more about the application of terminals, see Terminals.
The following steps are involved with managing terminals:
- Create a terminal configuration defining the names and directionality of a collection of terminals as well as the valid paths and the default path of connectivity between each terminal. .
- Assign the terminal configuration to one or more specific asset types.
- Set a terminal connection on a feature coincident with the endpoint of a line feature.
- Connect a terminal on a feature with the endpoint of an edge object, point feature, or junction object through a connectivity association.
- Modify the current path set on a feature—for example, switch it from A-B to A-C; the network resource now flows out of C instead of B.
Terminals impact traversability-based traces. Carefully consider terminal configurations and feature placement, such as where the starting point is placed when tracing on a network with terminals. To learn more, see Connectivity and traversability.
Create a terminal configuration
Use the Add Terminal Configuration tool to create a terminal configuration. Once created, a terminal configuration can be assigned to specific asset types on devices and junction objects.
The default terminal configuration assigned to asset types is Single Terminal. This value remains until a user-defined terminal configuration is assigned. The Single Terminal configuration can be reassigned to an asset type using the Set Terminal Configuration tool when you want the device or junction object to behave like a feature without terminals.
You specify the following options when creating a terminal configuration:
- Directionality—Define how resources flow through the terminals: directional or bidirectional.
- Terminal specifications—Specify the number of terminals, the name of each terminal, and whether they are upstream or downstream.
- Valid paths—Specify the paths a resource can take through a feature with more than two terminals.
- Default path—From the set of valid paths, identify one to be assigned by default.
All terminal configurations require directionality to be defined. Directionality controls how a network commodity can flow through a feature. A directional terminal configuration indicates that one or more of the terminals are upstream and will restrict flow of the network commodity through the feature. A bidirectional terminal configuration indicates that there are no distinct upstream or downstream terminals; the network commodity travels in either direction through the feature. The following apply to terminal configurations:
- When a domain network has a partitioned tier definition, its subnetwork controllers must use a directional terminal configuration.
- When a domain network has a hierarchical tier definition, its subnetwork controller can use a directional or bidirectional terminal configuration.
In a terminal configuration, terminals are specified to indicate the number of connection points that exist for a feature and to provide a name for each. If the terminal belongs to a directional configuration, each terminal will indicate whether it is on the upstream or downstream side of the device. All terminal configurations require at least two uniquely named terminals. The maximum number of terminals in a configuration is eight. If the configuration is Directional at least one terminal must be specified as the upstream terminal.
Upstream and downstream terminals are configured to establish a device's directionality and the permitted flow of resources. Both the directionality and valid paths defined for a terminal configuration are honored during a trace to define traversability and dictate how a commodity flows through and within a feature. Flow direction for the entire subnetwork is determined by the subnetwork controller type (source or sink) set for a domain network. Subnetwork controllers set on terminals designated as downstream (according to the terminal configuration) behave as sources in a source-based network. Subnetwork controllers set on terminals designated as upstream behave as sinks in a sink-based network. To learn more, see Subnetwork controllers.
When three or four terminals are specified, valid paths must be configured, and a default path must be set. Valid paths denote the paths a network commodity can take when it enters a feature. If only two terminals are specified, there is no need to set valid paths, because there is only one. Valid paths can be a terminal pair (single path), a collection of terminal pairs, all paths, or no paths. A terminal pair denotes a single path in which a commodity can travel. For example, A-B states the resource can flow in through A and out through B or in through B and out through A. Although all the paths are always present, configuring a set of valid paths is useful for restricting the paths a resource can travel along.
Note:
Terminal configurations with five to eight terminals do not support defining valid paths; instead, all paths are valid.
If there is more than one valid path, a default path must be set. A default path is assigned to a feature when it is created. The current path set on a device feature or junction object is stored in the Terminal Configuration attribute. The path assigned to a feature can be modified in the Modify Terminal Paths pane.
Dive-in:
When terminal configurations are created for a utility network, the terminals are stored collectively in a single coded value domain. The code is system generated, and the terminal name is stored as the description. This domain is assigned to the domain network line feature class using two attribute fields which manage the connectivity between line and device features that have terminal configurations assigned: fromdeviceterminal and todeviceterminal. These attributes refer to the device at the first vertex and last vertex of the line respectively and are not related to the direction in which resources flow in the network. Connectivity between edge objects and junction objects with terminals are managed through connectivity associations. When configuring a utility network, the order in which terminal configurations are created is very important if existing features will be loaded that are using terminals for connectivity.
You should carefully review your terminal configuration settings before creation. Once it is created, a terminal configuration cannot be changed except in a scenario where it has not been assigned and the network topology has never been enabled. For more information, see Delete a terminal configuration.
Assign a terminal configuration
Once a terminal configuration has been established, it can be assigned to asset types in the Device feature class or JunctionObject table. This is accomplished by the administrator of the utility network using the Set Terminal Configuration tool.
A terminal configuration can be assigned to more than one asset type, but an asset type can only be assigned one terminal configuration. An asset group can have many asset types, each with a different terminal configuration. Any feature that does not have a terminal configuration assigned has a Single Terminal configuration.
To learn more about assigning terminal configurations, see Set a terminal configuration.
Modify paths assigned to a feature
When a terminal configuration is assigned to an asset type, a feature created with that asset type is created with the default terminal path. The type of terminal configuration that is assigned to an asset type, along with the default path of the terminal configuration is shown on the network properties page of the utility network layer. Information about the default path that was assigned is stored in the Terminal configuration attribute.
Modify the default path in the Modify Terminal Paths pane. This pane displays a list of the valid paths for the terminal configuration assigned to the asset type of a feature. Selecting a Path value from the list changes how a resource flows through the feature by updating the Terminal configuration attribute for the feature.
Example
A bypass switch allows an inline electric device, such as a voltage regulator, to either function in an energized state or become de-energized for maintenance.
This type of switch is modeled as a four-terminal device. There are six possible paths between the four terminals, but the valid paths defined in the terminal configuration either energize or de-energize the inline device.
The middle device above shows the bypass switch isolating the inline device by restricting the valid path to travel from terminals 1 to 2. The third device above shows the bypass switch energizing the inline device by allowing the flow of electricity to travel along two valid paths: 1 to 3 and 4 to 2.
To learn more, see Modify terminal paths.
Connect to and disconnect from a terminal
Use the Modify Terminal Connections and Modify Associations panes to create or delete connectivity to a terminal. Both panes evaluate the respective network rules to check that the attempted connectivity is allowed. If there is no rule to allow the features to connect, they are not added to the pane and instead an error is returned.
Use the Modify Terminal Connections pane to manage connectivity between a line feature and the terminals of device features connected to either end of the line. Use the Modify Associations pane to establish connectivity between two features or nonspatial objects and their terminals. Devices or junction objects with the default terminal configuration value of Single Terminal are not included in the Modify Terminal Connections pane, as there is only a single logical port to connect.
Junction-edge connectivity rules support line end connectivity to a device feature or junction object with terminals. Features with terminals cannot be placed midspan on a line because each line stores the terminal Ids of the connected devices at its first and last vertex in the FromTerminalID and ToTerminalID fields. You may work around this limitation by either splitting the line or creating a junction or device without terminals midspan along the line, then connecting the terminal device to that point feature using a line or connectivity association.
In the example below, junction-edge connectivity is established between the midspan tap junction and a medium-voltage line. A junction-junction connectivity association is then established between the midspan tap junction and the high side of the transformer device. This connectivity association is established using the Modify Associations pane.
Access terminal information
The terminal configurations available in a utility network are listed in the Terminal Configurations section of the Network Properties dialog box. This section shows each terminal configuration along with its directionality model, terminals, and valid path.
The current terminal path of a feature is stored in the Terminal configuration attribute. Features with an asset type that does not have a terminal configuration assigned must use Default for the Terminal Configuration attribute.
Terminal configuration assignments are found in the Terminal Configuration Name column for device and junction objects in the network properties. When no terminal configuration is shown, the asset type uses the default terminal configuration of Single Terminal.