| 摘要 |
The first stage of a cooling sequence for the extruded, thick-walled thermoplastic polyethylene insulation on high tension and high frequency cables, consisting of a number of separate cooling stages at normal pressure is operated at temps., between 100 degrees C and that of the insulation coating entering it. A cooling fluid is used, the boiling point of which is sufficiently above the working temp. of the first stage, to prevent localised evaporation. A pref. cooling fluid is based on one or more aliphatic hydroxyl hydrocarbons, opt. in aq. soln., having a boiling point of 150 degrees C and 0 50 kcal m.h degrees C and a specific heat between 0.30 and 0.90 kcal/kg degrees C, at 100 degrees C. Reverts to cooling at atmospheric pressure, dispensing with complicated seals for the passage of the cables, whilst avoiding the difficulties arising from the use of water alone. |
