Aging Characteristics and Lifespan Prediction of 3240 Fiberglass-Epoxy Material Under Pulse Electrical Aging

Abstract

Pulse coils are essential components in the field of pulse power technology, while 3240 fiberglass-epoxy material is a commonly used solid insulation material in producing electromagnetic coils. However, research on its pulse electric field aging characteristics and life prediction is limited. This article investigates the aging characteristics and life prediction of 3240 fiberglass-epoxy material under pulsed electric fields. First, the discharge conditions of the electromagnetic coil under pulse voltage were analyzed through simulation, determining the level of voltage impulses endured by the 3240 material. Based on the simulation results, an equivalent pulse electric aging testing platform was established. The platform was utilized to conduct pulse electric aging tests on 3240 fiberglass-epoxy samples using voltage levels of 3, 4, and 5 kV, and varying numbers of impacts ranging from 100 to 700, as well as 1000 and 1500 impacts. Scanning electron microscopy (SEM) observation and infrared spectral microanalysis were carried out on the pulse electrical aging test specimens. The SEM results indicated that the insulation defects on the surface of the epoxy resin material increased with the number of pulses and voltage. The infrared spectral results showed that the strongly polar groups in the epoxy resin material continuously rotated and moved under the action of the pulse electrical field, leading to the breaking of ether bonds connecting the molecular chains and the decrease in the aging life of the 3240 fiberglass-epoxy material. Breakdown tests under high voltage were conducted on regular samples, demonstrating that the breakdown voltage for 2-mm-thick samples reached 40 kV, far above the actual working voltage. Therefore, it is not suitable as a criterion for life evaluation. Impact strength tests were conducted, and the aging trend of 3240 fiberglass-epoxy material under pulse electrical aging was analyzed. The lifetime prediction formulas for different impact voltages were derived. Then, the aging life of the 3240 fiberglass-epoxy material under the three impact voltages was calculated. Furthermore, it is shown that accurate life prediction results can be obtained by conducting impact tests up to a maximum of 700 cycles. The equivalence method proposed in this article for insulation material electric aging impact tests and the coil life prediction method offer valuable insights.