Terminals represent logical ports, entries, or exit locations on a single point feature. A key use of terminals is to set them as subnetwork controllers to define the origin of a subnetwork. Terminals create internal paths within a device; from those paths, a set of valid paths can be established to control how a commodity can flow through a device at different states. To learn more about the application of terminals, see Device terminals.
There are several steps involved with managing terminals:
- Create a terminal configuration defining the name and directionality of terminals as well as valid paths and the default path (from the set of valid paths, select which one will be present when a feature with the terminal configuration is created).
- Assign the terminal configuration to specific asset groups and asset types in the device feature class.
- Modify the current path set on a device feature, for example, switch it from A-B to A-C; the network resource now flows out of C instead of B.
- Connect to a terminal on a device feature with a connectivity association to a point or coincident with a line end.
Terminals impact traversability-based traces. Careful consideration should be taken with terminal configurations and feature placement. Tracing on a network with terminals warrants consideration with regard to where the starting point is placed. To learn more, see Connectivity and traversability.
Create a terminal configuration
The Add Terminal Configuration tool is used to establish a terminal configuration. Once created, a terminal configuration can be assigned to the device feature class for specific asset groups and asset types.
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 on the fromdeviceterminal and todeviceterminal fields, and is used to manage the connectivity between line and device features that have terminal configurations assigned. 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.
The default terminal configuration assigned to the device feature class for all asset groups and 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 when you want your device feature to behave like a point without terminals. This is done using the Set Terminal Configuration tool.
Creating a terminal configuration requires the following considerations to be made:
- 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 that is assigned when a feature with the terminal configuration is created.
All terminal configurations require directionality to be defined. Directionality controls how a network commodity can flow through a device: directional or bidirectional. A directional terminal configuration indicates the network commodity can travel only one way through a device. A bidirectional terminal configuration indicates there are no distinct upstream and downstream terminals; the network commodity travels in either direction through the device. For domain networks with a partitioned tier definition, a directional terminal configuration is required for subnetwork controllers. Domain networks with a hierarchical tier definition support direction and bi-directional subnetwork controllers.
In a terminal configuration, Terminals are specified to indicate the number of ports on a device, the names of the ports, and whether the port is upstream or downstream. All types of terminal configurations require at least two uniquely named terminals. The maximum number of terminals a configuration can possess is eight. If Directional was set for the type of directionality, a minimum of two terminals must be set with one specified as upstream.
Upstream and downstream terminals allow flow direction to be determined within a device on the fly during tracing events. The terminal configuration therefore dictates how a commodity flows through and within a device based on the valid paths defined. 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 (as per 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 which paths a network commodity can take when it enters a device. 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 may travel.
Terminal configurations with five to eight terminals do not support the 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 the path assigned to a device when it is first created. The current path set on a device is stored in the Terminal Configuration attribute. The path assigned to a device can be modified using the Modify Terminal Paths pane.
A terminal configuration can be removed from a utility network only if it has not been assigned and the network topology has never been enabled. See, Delete a terminal configuration.
Assign a terminal configuration
Terminal configurations are created using the Add Terminal Configuration tool. After a terminal configuration has been established, it can be assigned to asset types in asset groups within the device feature class. 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 may only be assigned one terminal configuration. An asset group can have an assortment of asset types, each with a different terminal configuration. Any device that does not have a two or more 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 of the configuration set. The type of terminal configuration that has been assigned can be found on the properties page of the utility network layer. Information about the default path that was assigned is stored in the Terminal Configuration attribute.
The default path is modified by using the Modify Terminal Path pane. This pane presents 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.
You can modify the terminal paths for a feature to redirect resource flow to another part of the network. For example, a tri-state switch with four terminals, A, B, C, and D, has a line connected to each of the terminals. The current terminal path set for a feature is A-B; where the resource flows in through the A terminal and out through B. To switch electric flow from A-B to C-D, the path for that feature is modified to use the C-D valid path.
To learn more, see Modify terminal paths.
Connect to and disconnect from a terminal
The Modify Associations and Modify Terminal Connections panes are used to create or delete connectivity to a terminal. Both panes evaluate the respective rule sets 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.
The Modify Associations pane is used to establish connectivity between a point and a terminal on another point or between two terminals from different points. The Modify Terminal Connections pane is used to manage connectivity between a line end and a terminal on a point. Devices with the default value of Single Terminal do not require the use of the Modify Terminal Connections pane as there is only a single logical port to connect instead of multiple.
Devices with terminals cannot be located midspan on a line feature. A connectivity association can be used to connect a device with terminals to a midspan junction feature. The following image shows a connectivity association that is established between a midspan tap junction on a medium voltage line and the high-side terminal of a transformer device feature. 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 Network Properties dialog box in the Terminal Configurations section. The terminal configuration assigned to specific asset groups and asset types is also listed within the domain network section for the Device feature class under Terminal Configuration Name. The default terminal configuration listed for all assets without a user defined terminal configuration is Single Terminal.
Valid Paths values for a terminal configuration can be viewed in the Network Properties dialog box. The current terminal path assigned to a feature is stored in the Terminal Configuration attribute for the Device feature class. When all paths are valid, for example, in a two-terminal or five-terminal configuration, Default is listed in the Terminal Configuration attribute. Assets that do not have a terminal configuration assigned to their asset type have Default present for the Terminal Configuration.
Here is an example of terminal configurations in use.
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 image above shows the bypass switch isolating the inline device by restricting the valid path to be from terminals 1 to 2. The third image on the right shows the bypass switch energizing the inline device by allowing the flow of electricity to travel allow two valid paths; 1 to 3 and 4 to 2.