P35.018: Line Switch Management
Objective
Transmission line switches are critical assets for the resilience of the transmission system given that they minimize outage impacts by remotely isolating faulted line sections following outage events or serving as mechanisms for control of load flow. Thus, line switches are important systems designed to enhance the resilience of the grid. However, line switches may introduce additional issues and jeopardize the installation if not properly designed, installed, or maintained.
Moreover, the many options of configurations and manufacturers pose an additional challenge with respect to asset management as different switches can have different installation and maintenance requirements.
This project aims to support utilities in reducing maintenance costs and maximizing the reliability of line switches through engineering tools and information for design, testing, installation, inspection and assessment, and troubleshooting.
Research Value
- Enhanced safety for utility workers and the public through safe switching operation
- Improved reliability of electric service through effective specification, design, installation, and operation of line switches
- Reduced “premature failures” through optimized commissioning protocols of new line switches
- Improved effectiveness of inspection and condition assessments
- Guidance for cost-effective methods for implementing condition-based maintenance and replacement strategies
- Improved expenditure and capital cost planning through enhanced understanding of performance, component aging, and deterioration mechanisms of line switches
- Guidance for decision making on operations and maintenance (O&M) based on field data and condition ratings
Approach
This project addresses critical issues related to the selection, application, and maintenance of line switches by undertaking specific tasks in 2026:
Test Quick Break Whip Devices: This task intends to develop guidelines and determine, through laboratory testing, the performance and current handling of quick break whip arc interrupting devices. Since there is currently no test methodology for evaluating quick break whips, this research is intended to advance the knowledge and understanding of laboratory evaluation of these devices. In 2026, EPRI intends to continue to work on electrical and endurance testing, and on developing a free-air arc model.
Develop Inspection and Maintenance Considerations for Line Switches: This task investigates the use and application of existing, new, and emerging technologies for inspecting, assessing, and monitoring the health conditions of line switches. The information obtained is intended to be compiled into a comprehensive guide to form the basis for understanding components, inspection, and monitoring techniques. Technologies such as unmanned aerial systems, testers, and sensors are intended to be explored. In 2026, EPRI intends to work on additional detailed inspection procedures for specific components, such as motor operators, and to include new line switch models in the electronic form for inspection of line switches.
Develop Transmission Line Switch Vintage Guide: This task aims to develop a comprehensive technical resource intended to provide guidance and strategies on procedures to assess the condition of transmission line switches in service by model and vintage. For that, underlying failure and degradation modes and mechanisms have been identified and catalogued by component to help estimat life expectancy and required maintenance actions. In addition, this task assists utilities in the performance of root cause and failure analyses. In 2026, EPRI aims to include results of additional forensic investigations and compile case studies provided by utilities.
Catalog Component Degradation Modes: This task seeks to catalog degradation modes of line switch components from different manufacturers. Every year EPRI updates the Transmission Resource Center (TRC) with new findings from forensic investigations performed in previous years and utility reports.
Update Practical Installation Guide of Line Switches: This is a living task intended to provide the technical basis and guidelines to support and help in-the-field engineers and technical staff with information regarding component specification, design, installation, and commissioning protocols of new equipment, as learned through best practices. In 2026, EPRI intends to continue working on a compilation of utility line switch installation design templates.
Evaluate Motorized Switches: This task seeks to gain a better understanding of the functionality of and the inspection techniques required for motorized switches compared to manually operated switches. Possible topics include the additional components needed for motorization, such as batteries, SCADA, and alternatives of power supply. Findings from this task are shared through the Inspection and Maintenance Guide and the Line Switch Vintage Guide Technical Update.
Provide Tools and Resources on the Transmission Resource Center: The following calculators, tools, result summaries, and references are planned to be available on the Line Switch Transmission Resource Center:
| Resource Title | Resource Type |
|---|---|
| Whip Testing | Calculator |
| ESRI Survey 123 Form for Commission of New Line Switches | Results Summary |
| Quick Break Whip Testing –Intro on Interrupting Capacitive Currents | Results Summary |
| Line Switch Commissioning 101 | Results Summary |
| Selected Standards | Reference |
Anticipated Deliverables
| Deliverable Title | Deliverable Type |
|---|---|
| Quick Break Whip Testing – Electrical and Mechanical Endurance Testing | Technical Update Report |
| Inspection and Maintenance Guide | Technical Update Report |
| Transmission Line Switch Vintage Guide | Technical Update Report |
Past EPRI Work on Topic
| Product ID | Title | Description | Year Published |
|---|---|---|---|
| 3002029612 | Inspection and Maintenance of Transmission Line Switches: 2024 Updates on Failures and Degradation Modes | This report highlights inspection criteria and maintenance techniques for transmission line switches. In 2024, EPRI developed test procedures for vacuum interrupters, and show cased inspection and testing tools as well as a procedure for forensic investigations for the same component. | 2024 |
| 3002027141 | Practical Maintenance Guide for Installation of a Transmission Line Switch: Vacuum Interrupters and Utility Experience | Transmission line switches enhance line availability and resiliency by isolating faults and controlling load flow, with remote monitoring capabilities, but may reduce reliability if not properly managed. This guide offers practical information on components, installation, and commissioning of line switches. The 2023 report includes new sections on 115-kV equipment, auxiliary arc extinguishing devices, and siting practices. | 2023 |