Comparison of Voltage-time to Surface Failure of Various Insulation Material for Space Aerial Cables

Abstract

This paper aims to represents the investigation of surface tracking resistance of various types of cable insulations. Five kinds of cable material i.e. non carbon filled crosslink polyethylene (XLPE), carbon filled XLPE, low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE) were examined. The test specimen has a dimension of 10 mm in width, 50.8 mm in length and 1.52 mm in thickness. The test samples were classified into two groups for investigation. The former group was the new test samples, whereas the latter test samples were stressed by thermal ageing with 120oC for 168 hours. Then both specimens were examined. One side of the specimen was contacted with high voltage electrode terminal made of 1 mm diameter Nichrome wire. Another side of the test specimen was dipped into 0.1 percent solution of ammonium chloride as grounded electrode. The spacing between electrodes at dry area was determined for 25.4 mm. After completion of the test set up, AC high voltage was applied to the test specimen. The dip rate of the specimen into the solution was set up as 4 times per minute. The test voltage level was in the range of 1-3.5 kV. The experiment was performed in accordance with ICEA S-66-524 (Method B). The test voltage was applied to the test specimen until the insulation failure could be observed. Then, the insulation failure voltage and failure time were recorded. The test results illustrated that both unaged and aged HDPE and non carbon filled XLPE provided the higher surface tracking resistance than carbon filled XLPE, LDPE and MDPE respectively. Besides, the thermal stress aging had not much effect on the surface tracking resistance characteristic of tested material. It can be summarized that the material structure much more influenced the surface tracking characteristic of the cable material.