Abstract

This paper presents a study of electrical trees partial discharges in three different epoxy resins namely, RPU315, FR/974/SF and FR/64 that are commonly used in power cable accessories. The work is motivated by problems recently experienced in a case of mining machinery where high voltage power cable connectors using RPU315 epoxy had consistently prematurely failed. It was therefore needed to evaluate the insulation strength of the epoxy in question relative to other epoxy types that are used in power cable accessories. Electrical treeing is a pre-breakdown phenomenon in solid insulation such as epoxy resins, rubbers, and polymers. The electrical tree partial discharges are measured using a partial discharge measurement set-up in accordance with the IEC60270 standard. Partial discharge characteristics are observed as the electrical trees grow from inception, propagation through to breakdown. The classical point-to-plane electrode configuration cast in the epoxy is used to simulate a defect inside the epoxy resin creating an intense localized stressed region. The characteristics showed that the electrical tree inception occurred at the lowest voltage of 1.43 kV in RPU315 epoxy showing that it is the weakest of the three epoxies studied. The strongest epoxy proved to be the FR/974/SF with an electrical tree inception voltage of 1.70 kV. It was found that the phase-resolved partial discharge patterns of RPU315, FR/974/SF, and FR/64 epoxies represented bush type, branch-type, and bush-branch type tree structures respectively. Bush trees manifest the presence of multiple paths for partial discharge activity and fast deterioration, whereas branch-type trees represent fewer paths for partial discharge activity to grow in the insulation. Among the three types of epoxies investigated, the FR/974/SF epoxy is found to be the most durable type as it has the highest electrical tree inception voltage meaning that it sustains electrical treeing PD activity much longer.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.