Insulation Performance of a Hermetically Sealed and Process Cooled Motor-Compressor Exposed to Water-Saturated Natural Gas Environments

In this paper the impact on the dielectric performance of an epoxy-mica-composite insulation system exposed to a water-saturated hydrocarbon gas environment under pressure, as used in a hermetically sealed process-cooled motor-compressor, is presented. Two litz-wire loops, both insulated with the same system, were built to allow for the simultaneous application of direct current (DC) during the aging process, and thus for the investigation on the effect of the resulting copper-based losses during exposure. Results for both the DC-heated loop and the passive control loop are presented. The measured dielectric response shows clear recovery and eventual preservation for the DC-heated loop in comparison to the wetted-control-loop. The effect of multiple heating and depressurization cycles is also presented.