Studies on behavior of dielectric synthetic ester under the influence of concentrated heat flux

This paper presents the results of studies on the behavior of synthetic ester under the influence of concentrated heat flux. In the specially designed and built experimental system the heat treatment of tested ester was simulated. The simulation was carried out on the terms which are used commonly in industrial applications. Analysis of behavior of the ester was based on the indicators such as the dielectric dissipation factor (DDF), gases dissolved in ester (using DGA technique) and FITR (Fourier Transform Infrared Spectroscopy) spectrum as well as on the direct observation and registration of the process using digital camera. The conditions of the heat treatment were defined by unitary surface load of the used heater, which was expressed in W/cm2. For different values of unitary surface load the heating processes were conducted and then above mentioned indicators were analyzed. The results of the studies showed that with an increase of unitary surface load the DDF of ester also increased from the initial value equal to 0.0108 to the value of 0.0377 at maximum load. Simultaneously, no changes were registered in FTIR spectrum and during DGA measurements. A small correlation was however observed between the subsurface phenomena called "adhesion" and increase of DDF value. It seems that overheating of the ester is not possible during the heating process, but even if it appears to some extent, it does not result in the form of liquid decomposition or gas generation.