The effect of molecular structure on the properties of dielectric fluids

The dielectric properties of six test fluids (MDBT, DTE, DINP, PXE, PFPE, and PPMS) were evaluated under AC and DC stresses. The data suggest that DC conduction is less sensitive to molecular structure effects than to impurities while AC conduction reflects more molecular characteristics. Within a family of fluids such as liquid aliphatic hydrocarbons, both the AC and DC breakdown level are adversely affected by impurities which increase their conductivities. Among different types of fluids, molecular structure has a significant impact on DC impulse breakdown. Conventional (50 or 60 Hz) AC breakdown appears to be much less sensitive to structural effects.>