P35.012: Porcelain and Glass Insulators
Objective
As populations of porcelain and glass insulators approach or exceed their expected service life, utilities are seeking end-of-life metrics to prioritize maintenance and replacement programs. To achieve this, utilities seek information on insulator performance (both new and in-service), how to determine replacement strategies, and what tools and technologies are effective to inspect and assess them. As utilities replace aging insulator populations, developments in glass insulator designs and shifts in porcelain insulator manufacturing have required new training for utilities on the selection, application, and inspection of porcelain and glass insulators.
Concerns have also been raised over the performance of new insulators from traditional and nontraditional vendors. In addition, many utilities that have not used glass insulators are considering this technology. Recently, manufacturers have been introducing factory-applied room-temperature vulcanized (RTV) silicone rubber coatings on glass insulators to enhance their contamination performance. However, there is limited information on the long-term performance of the coating and how it affects inspection, assessment, and maintenance.
This project intends to address the technical challenges with aging insulator populations and shifts in design and manufacturing in the following ways:
- Develop test methods that assess new and novel designs (including rubber coatings) with in-service representative conditions
- Evaluate results and measurements collected from traditional and nontraditional tests to assess the overall condition of aging insulator populations
- Create and update training and reference material for effective knowledge transfer
Research Value
This project can provide the following benefits:
- Help select, inspect, and maintain glass and porcelain insulators
- Provide information on insulator technologies, enabling lower cost and/or improved technical solutions
- Improve understanding of the performance issues of existing and new insulators applied in contaminated environments and how to address those issues
- Evaluate and identify high-risk porcelain/glass insulators or populations of insulators prior to failure, which helps maintain a reliable electricity supply to the public
Planned 2025 Research
This project seeks to enhance the industry’s knowledge of porcelain and glass insulators in the following ways:
Porcelain and Glass Insulator Vintage Guide: Much of the industry has a history of using porcelain insulators; therefore, assessing and managing these aging populations will be required for many years. However, test data alone are just one component of deciding the end of life. In addition, the use of glass insulators is increasing. This task plans to develop guidance combining the necessary information in a guide to help utilities assess failure risk and determine when population replacement is required based on make and vintage of insulators.
Evaluation of the Performance of RTV-Coated Insulators: Manufactured RTV-coated glass insulators are relatively new to the market and have limited worldwide experience. This task intends to evaluate how RTV coatings perform in various service environments. EPRI plans to perform various short-term and monitor long-term testing to assess coating performance in 2025.
Glass Insulator Failure Studies: Glass insulators have recently become more common across the industry. As more are being used, reports on shattering may increase. Having tools to understand the cause of the shattering can decrease time to issue resolution. EPRI intends to build on existing data to develop methods to determine how glass insulators are failing.
E-Field Modeling Software Update: As RTV silicone-coated glass insulators emerge in the market, controlling corona to reduce degradation of the RTV becomes essential. This tool can help calculate the electric field stress along an insulator string to determine if grading devices are needed. EPRI continually works with user feedback to keep this tool relevant and easy to use.
Insulator Reference Book: A comprehensive reference guide that provides state-of-the-art information on insulator selection, inspection, and maintenance. In 2025, EPRI intends to refresh the information with the latest research results. There has been new development in contamination research that can enhance the existing information in the book.
Anticipated Deliverables
In 2025, a mix of ongoing research initiatives together with new research areas will be undertaken.
| Deliverable | Type | Date |
|---|---|---|
| Insulator Reference Book (The Violet Book) | Reference Book | December 2025 |
| Insulator E-field Modeling Software (Insulator Calculation Engine [ICE]) | Software | December 2025 |
| Porcelain and Glass Insulator Vintage Guide) | Technical Update | December 2025 |
Past EPRI Work on Topic
| Product ID | Title | Description | Published Date |
|---|---|---|---|
| 3002027069 | A Study of Aging Porcelain Insulator Performance | This report presents test data showing how the age of insulators affects their strength performance. | December 2023 |
| 3002024448 | Results of Salt-fog Testing Insulators with RTV Coatings | This report describes the process to perform salt fog flashover testing of glass insulators with RTV coatings. | December 2022 |
| 3002021554 | Summary of Lessons Learned on Failure Analysis of Porcelain Insulators | This report summarizes the forensic analysis of several porcelain insulator failures and the lessons learned. | December 2021 |