THE EFFECT OF MOLECULAR-STRUCTURE ON THE PROPERTIES OF DIELECTRIC FLUIDS

With the advent of several new synthetic dielectric fluids of well-defined composition, it has become possible to study the effect of molecular structure on the electrical properties. This paper reports on the results of such a study. The dielectric properties of six test fluids are 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 de breakdown level are adversely affected by impurities which increase their conductivities. Among different types of fluids, molecular structure has a significant impact on de impulse breakdown. Conventional (50 or 60 Hz) ac breakdown appears to be much less sensitive to structural effects.