Characterization of Insulation Aging with Power- Dense Environments

Abstract

As machine environments become more power-dense, understanding the aging of insulation is critical for successful machine design and performance. It is well-known that electrical aging under stress can be monitored over time using partial discharge and breakdown strength. There are also tests that indicate comparative “condition”, such as polarization index and dielectric discharge. These characterizations give little information as to the nature of the aging, necessary for specifying new or improved materials. Such information would also be useful in machine design decisions. A survey of materials characterization tools was made to assess the nature of aging under mechanical, thermal, and electrical stresses. The use of three tools is recommended for characterization of the nature of aging in electrical insulation materials: Dielectric Thermal Analysis (DETA), Dynamic Mechanical Analysis for extension (DMA-Extension), and Dynamic Mechanical Analysis for shear (DMA-Shear). With these tools, significant differences are found between the aging behaviors of materials (e.g., between unfilled epoxy and silicone thermoset polymers).