An extruded polyethylene model cable has been examined for its electrical insulation performance at cryogenic temperature. The impulse voltage breakdown test, AC voltage breakdown test and partial discharge test were carried out at 77 K.
The positive and negative impulse breakdown stresses were above 267kV/mm and above 300kV/mm respectively. The short term AC voltage breakdown occured at the terminals which assured that the breakdown stress was more than 56kV_rms/mm. No partial discharges were detected inside the cable sample over 1pC discharge magnitude up to 40kV_rms, while partial discharges at the terminals reduced the life at the service stress. The extruded polyethylene cable had appropriate insulation performance at cryogenic temperature except for the cable terminations.

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