On the Erosion- and Arc-Resistance when Tested with DC- and AC-Stress by the Example of Silicone Elastomers

Summary

The paper provides inclined-plane-test results that were collected with modified upper electrodes made from tungsten, gold-plated tungsten and a platinum-iridium-alloy. Tungsten- as well as gold-plated tungsten electrodes show corrosion effects like those that are found with steel in the standardized test. The platinum-iridium-alloy does neither show corrosion effects nor weight loss even after a total test time of 40 hours. It can be considered corrosion resistant under the applied conditions in the inclined-plane-test. Nevertheless, a comparative evaluation of the erosion depth and the weight loss of the specimens doesn't show a significant influence of the electrode-material in the deterioration of the tested material. Further investigations with the high voltage arc-test with AC and DC voltage in a step test similar to IEC 61621 are provided. The paper reveals that depending on the insulation material the arc-test withstand time in a DC-step-test can be lower or equivalent to those at AC stress. Furthermore in comparison to the test at AC there seems to be an intensification of the stress at higher levels of the test current under DC stress. To better understand the cause of this the arc-dynamics are investigated by using a high-speed-camera. It is found that the arc shows a rather high mobility at the cathode at low current. Increasing current leads to lower mobility of the arc. Additionally the insulating material itself seems to affect the mobility of the arc.

Additional informations

Authors

Okubo Hitoshi, Sakai Takayuki, Furuyashiki Tatsuki, Kato Katsumi