Updates & Events

The different efforts performed in P37.113, both past and present, aim to provide long- and short-term insights and information of polymer bushing use for users. Insights into operation, maintenance, and failure are the focus for these studies.

Status

Long-term performance of polymer bushings under extreme environmental conditions
Three new, unused ABB resin impregnated synthetic (RIS) bushings have been installed and energized for more than five years at the EPRI outdoor 138 kV Research Substation in Lenox, MA. While varying loading conditions using a defined test plan, the RIS bushings have been subjected to various harsh conditions (i.e., below freezing temperatures, ice formation, heavy snow accumulation, high ambient temperatures (>100oF/>40oC), direct solar radiation, multiple sequential days of heavy rain, high winds, and others). Selected physical, chemical, and electrical properties of the bushings are tested each year using offline testing or a bushing monitoring system. The results of the tests can be compared to oil impregnated paper bushings (OIP) connected to the same systems that are also subject to the same environmental and loading conditions.

• Offline testing of hydrophobicity, power factor, capacitance, and dielectric frequency response (DFR) for the RIS bushings is planned for Q2 2025 and Q4 2025.
• The bushings will continue to be energized and subject to the various outdoor environmental conditions throughout 2025 to obtain more insight into their aging.

Guidelines on specification and maintenance of polymer bushings
This document contains the best and most recent information available to the industry for polymer bushings.

• The 2023 revision of this document included material on the load capability of polymer bushings for the first time. Research in 2024 added additional experimental insights to this important topic and went through a revision to include additional recent standards and references, as well as clarity in the text.
• In 2025, a survey of utilities, other polymer bushings users, and subject matter experts will be performed in an effort to obtain and summarize collective experiences different groups have directly had using polymer bushings in the last 6 years. Additionally, further information on bulk polymer based bushings is planned to be included in the document due to their increased use.

Limits and degradation mechanisms of polymer bushings (Supplemental Studies)
Targeted studies (i.e. supplemental projects) probing specific aspects of polymer bushing performance, such as sensitivity to overload, continue to be petitioned and performed.

• A new aging chamber for accelerated bushing testing has been constructed and is being subjected to the final commissioning checks in the first half of 2025. This chamber provides the ability to test 34.5 kV and 69 kV bushing using various voltage, current, ambient temperature, and humidity conditions. The first use of the chamber is with energizing 34.5 kV and 69 kV bushings at full ratings, using cycling elevated ambient temperatures, and an elevated static tank oil temperature to accelerate aging and degradation. The electrical properties of the bushings will be tested at scheduled intervals, and the 34.5 kV results compared to another 34.5 kV OIP bushing subjected to the same conditions.
• In 2025, baseline data will be collected to help in assessing the feasibility of a potential new supplemental project involving heating a polymer bushing(s) past the glass transition temperature of the contained resins, and assessing the changes/damage to the bushing(s).

Engagement Opportunities

Anticipated 2025 Deliverables

2024 Deliverables