ArcGIS Blog

Electric & Gas Utilities

ArcGIS Utility Network

Managing Electric Networks: Topology Errors

By Robert Krisher and Remi Myers

Introduction

Update: ArcGIS Pro 3.5 added new tools to bulk apply error resolutions to topology errors. The concepts outlined in this series of articles are important to understand when choosing which actions to use when resolving your errors. Learn more about how to use these new tools by reading the Analyzing topology errors and Resolving topology errors articles.

The first time you run the validate topology tool on your utility network and encounter a topology error you will likely ask yourself three questions:

  1. What caused this error?
  2. How can I fix this error?
  3. What can I do to prevent this from happening again?

The purpose of this article is to provide the industry specific examples of the most common errors, so you are better equipped to answer these three questions. The different resolutions aren’t always immediately obvious, and we hope this guide will help you quickly identify the best solution for your data and your specific situation. If you’re not already familiar with error management in the utility network, you will want to familiarize yourself with the following resources:

  • You can find a full list of all the possible network errors on the Errors topic in the online help.
  • Read the Feature restrictions and rules topic to learn the difference between a network rule and a feature restriction, along with the constraints for what types of features can be connected or associated.
  • Read the Dirty area management with the utility network article to learn how the utility network uses dirty areas to track and validate edits made to the network topology.
  • Read the Managing Topology Errors article for a higher-level overview of error management.

You can find more electric utility network related content in the ArcGIS Utility Network for Electric reading list.  You can also try these hands-on tutorials related to this article:

You can use the following links to quickly navigate to the different errors:

Error Type Error Description
Junction-Edge Errors 8: Invalid connectivity – No junction edge rule
Ambiguous Connectivity 9: Invalid connectivity – More than one junction edge rule applicable
Edge-Edge Errors 10: Invalid connectivity – The edges are different subtypes and cannot connect
Stacked Points 25: Stacked point features
Invalid Terminal Connections 36: The line feature has an invalid terminal
Midspan Terminal Devices 38: Devices with multiple terminals cannot be midspan

Junction-Edge Errors

Fix Incorrect data

If you convert an area from overhead to underground but you forget to update the asset type of one of the lines or devices in the area you will get this error. In this example you can see that one of the conductors wasn’t updated to be an underground conductor. Correct the asset type to be underground single phase to resolve the error.

Invalid connectivity errors happen when you attempt to connect features that do not have network rules allowing them to connect. In this example, one of the lines is improperly classified as an overhead conductor.
Once you've updated the asset type of the features in the utility network the error will be resolved. This change is something that should be verified in the field before updating the GIS.

Add a rule

If you add a new type of device to your data model, in this example unmetered load, but you forgot to add rules you will receive an error when you place the new feature type. To fix the error an administrator would need to add the rule(s) required for the new type of feature to allow it to connect to different lines, junctions, devices. The administrator would also update the subnetwork definitions to allow the new equipment to participate in different tiers of the network.

If you have features connected in your model that are not covered by the rules included in the model, and you've verified they exist in the real world, you can add a network rule to resolve the error.
Use the Add Rule geoprocessing tool to adding a network rule that allows the unmetered load to a low voltage conductor.

return to top


Ambiguous Connectivity

Use Modify Terminal Connections pane

When load breaking switches are placed at the end points of two lines you need to say which terminal each line is connected to. To correct the error you use the modify terminal connections tool on the each line to connect each line to a different terminal. It’s important that each line is connected to a separate terminal so the switch will stop flow when it is opened.

Ambiguous connectivity happens when a line can be connected to one of several terminals on a terminal device, but the specific terminal has not been specified.
Use the Modify Terminal Connections pane to specify which terminals the lines are connected to. In this case, the backbone is connected to the SS:S1 terminal on the fuse while the tapline is connected to the SS:S2 terminal.

Remove the invalid rule

If you see terminals available for connection that should never be used in your model, like connecting an overhead conductor to the bus side terminal of a circuit breaker, then an administrator should remove this rule from the network. To correct the issue, have an administrator remove the invalid rule and the issue should go away. Because there is only one terminal that the line can connect to it will automatically connect to the correct terminal on the device without the editor needing to use the modify terminal connections tool.

In this dataset, a circuit breaker always has busbar on the bus side of a circuit breaker, while the line side of the circuit breaker is always connected to a medium voltage conductor.
Our drawing standards allow us to remove the rules causing ambiguity.

Move one of the features

If you have two valid point features that are connected to a line, but the features happen to be stacked on top of each other, you will need to move one of these features. A common example of this is when placing a riser and a fuse on the same pole. To correct the error you will want to move the riser off the pole.

Ambiguous connectivity can also be a side-effect of stacked point features.
Placing the fuse along the tapline, instead of at the intersection of the mainline and tapline where the riser is, fixes the stacked point error and the ambiguous connectivity error.

return to top


Edge-Edge Errors


Create a point feature

If you have an overhead conductor connected directly to an underground conductor without a device or junction then you will also receive an error. You can clear the error by creating a riser between the lines. You should then get a crew to verify whether there is also some kind of device at the location like a fuse or disconnect switch, especially if the line is part of the backbone of the circuit.

An underground conductor cannot connect directly to an overhead conductor without a junction or device.
Adding a riser to the end of the underground conductor resolves the error.

Edit the features to match

This error will often occur when a feature is improperly classified. A simple example is a conductor with phasing ABC but an asset type of single-phase conductor that is connected to a three-phase conductor.  In this case you should update the classification of the single-phase conductor to be three-phase. This was caused by a conversion or data entry issue.

When a line is improperly classified this can result in an edge-edge connectivity error.
Looking at the phasing of both lines we can determine that they are both three-phase conductors. Fixing the asset type of the second line resolves the error.

Move a line

If you have a low voltage conductor connected directly to a medium voltage conductor, you receive this error. If the low voltage conductor energized from a transformer in another location, you should update the geometry of the line, so it no longer connects to the medium voltage conductor. If the low voltage conductor is energized from this location, then you should still disconnect the low voltage line, but you should investigate whether this secondary actually exists in the field and where the transformer is that it is connected to.

A low-voltage conductor cannot be directly connected to a medium-voltage line.
Because we do not know how this secondary is connected to the network, we disconnect it and dispatch a crew to field verify the area. This allows us to resolve the error and also makes it easy to identify the service as disconnected.

return to top


Stacked Points

Delete one of the stacked features

If you look at the two features and they appear to be duplicates than you should delete one of them. This will sometimes happen when an editor accidentally places the same feature twice.

Stacked point features can be caused by digitization errors, or even leaving removed/abandoned equipment co-located with active features.
Deleting the duplicate or out-of-service features is a common way of resolving the error.

Move one of the features

If you have two streetlights attached to the same pole, then you should disconnect and move one of the streetlights from the pole. If you energize your streetlights, you should either move the second streetlight along the secondary or create a new piece of secondary to ensure it stays energized.

Some stacked point features are caused by multiple features that are co-located in the field.
Redraw the features in the area so none of the features are stacked and all the features are connected to the network in a way that is consistent with the field.

return to top


Invalid Terminal Connections

Reset terminal connection

Terminal connections are stored on the line features that connect to devices. This means when you move, delete, or replace a device with terminals the line will still have attributes that reference the terminal from the previous line. A simple example of this is replacing a load breaking device with a disconnect device, because the original devices have terminal connections, and the new ones don’t.

Changing the asset type of a device to one with a different terminal configuration can result in invalid terminal ID errors for any lines connected to that device.

To fix this error use the Modify Terminal Connections pane to correct the terminal connections on each line, removing any invalid connections.

Use the Modify Terminal Connections pane to remove any invalid terminal connection and this will resolve the errors.

Connect new terminal

If you replace a device with terminals with a device that has a different terminal configuration you will also receive these errors. This will occur if you decide to replace load breaking switches with more sophisticated switches like bypass switches or T/V blade switches, since each of these switches has a different terminal configuration.

The bypass switch for this regulator is improperly classified as a generic load breaking switch.

Before you can use the modify terminal connections tool to assign the correct terminal you must manually set the terminal field, fromterminal or toterminal, to the value of “None”.  Once you’ve reset the terminal connection you can then use the modify terminal connections tool to assign the new terminal.

Changing the device to be a bypass switch introduces invalid terminal configuration errors, because bypass switches use a different terminal configuration.
Use the Modify Terminal Connections pane to update the terminal connections on the lines connected to the bypass switch to resolve the errors.

return to top


Midspan Terminal Device

Split the Line

If you place a device with terminals on a line without splitting it first, you will receive this error. If you place devices directly on lines you will encounter this issue when placing transformer or load breaking devices. To fix the issue you use the edit tool to split the line at the location where the device connects to the line. If you get an ambiguous connectivity error (type 9) after you’ve split the line you need to use the modify terminal connections tool to connect the lines to the correct terminals on the device.

When a device with terminals, like a transformer, cannot be drawn midspan on a line because the line won't be able to specify which terminal they are connected to.
Splitting the line will allow the lines in the area to properly identify the terminals associated with the first and last vertex of each line. If you have any invalid connectivity errors after splitting the line, refer to the instructions for those errors discussed in this article.

Move the device

Before you split the line you should make sure the device is in an ideal location, since it will split all lines connected to it. In the case of fuses or switches on tap-lines, you will want to make sure the device only split the tap-line and not the main-line.

In some cases, you may not want to have a terminal device drawn at the intersection of two or more lines, especially when those lines are medium-voltage or high-voltage.

After you’ve moved the device and split the line you will still need to use the modify terminal connections tool to connect the lines to the correct terminals on the device.

In those instances, you may decide to offset the device from the intersection, either moving them downstream one of the lines or creating a tap features with a junction-junction connection.

return to top

Share this article