No abstract

This paper deals with the influence of interface between polyethylene and semiconducting electrode on the space charge formation and electrical breakdown. Low‐density polyethylene (LDPE) films attached with different semiconducting electrodes were subjected to the DC breakdown test, and corresponding space charge distribution was measured. A heat treatment to LDPE itself did not bring about a significant change in space charge profile; however, when a semiconducting electrode was hot‐pressed, the impurities would migrate into LDPE at high temperature, leading to the change in space charge profile. Furthermore, it was suggested from the comparison between the results with degassed and as‐received semiconducting electrodes that some carriers relating to impurities in the electrode would move into LDPE under the voltage. In addition, it was shown that the breakdown is not determined by the field at the cathode which can supply sufficient electrons, but by the maximum field across the specimen, suggesting that an increase in conduction current due to the generation and/or injection, rather than the electronic avalanche process, leads to the breakdown. © 2001 Scripta Technica, Electr Eng Jpn, 138(3): 19–25, 2002

SUMMARYThis paper deals with the influence of interface between polyethylene and semiconducting electrode on the space charge formation and electrical breakdown. Lowdensity polyethylene (LDPE) films attached with different semiconducting electrodes were subjected to the DC breakdown test, and corresponding space charge distribution was measured.A heat treatment to LDPE itself did not bring about a significant change in space charge profile; however, when a semiconducting electrode was hot-pressed, the impurities would migrate into LDPE at high temperature, leading to the change in space charge profile. Furthermore, it was suggested from the comparison between the results with degassed and as-received semiconducting electrodes that some carriers relating to impurities in the electrode would move into LDPE under the voltage. In addition, it was shown that the breakdown is not determined by the field at the cathode which can supply sufficient electrons, but by the maximum field across the specimen, suggesting that an increase in conduction current due to the generation and/or injection, rather than the electronic avalanche process, leads to the breakdown. © 2001 Scripta Technica, Electr Eng Jpn, 138(3) : 1925, 2002

No abstract

In general, polycrystalline silicon is used as the material of solar module for a general photovoltaic power system. In the summer, the temperature of solar module remains over 60 degrees C for a long time in daytime. It is known that the conversion efficiency of the solar module remarkably drops because of the temperature rise. It is possible to keep the conversion efficiency high by watercooled equipment in photovoltaic power system. Furthermore, the cooling water can store heat energy from the solar module, so that a large amount of hot water can be produced. The results show that the water-cooled equipment has been effective in photovoltaic power system for a year.