Freezing of low and medium viscosity pipe type cable filling oils

An investigation was conducted to determine the response of various high voltage cable oils to cryogenic temperatures. Typical cooling and thawing curves were developed, through experimentation, for Sun Oil Company #4 Cable Oil and Cosden Low Viscosity Polybutene Oil under various initial and boundary conditions. During the course of this research, the freeze breakup and the possibility of cable damaging piston effects were also studied. Two theoretical approaches were developed to describe the freezing process observed during detailed experiments. Calculations were made and comparisons with actual measured high pressure freeze times discussed. As a result, an optimum freeze method was developed utilizing a liquid nitrogen bath in contact with the surface of the cable pipe.