Effects of artificial acid rain on water tree in crosslinked polyethylene insulation material

Abstract

Water tree was formed by applying an ac voltage of 15kV r.m.s. and 50Hz of frequency to the crosslinked polyethylene (XLPE). The experiment was accomplished with water tree test equipment using an artificial acid rain for different level of acidic. This experimental study focused on the effect of artificial acid rain on polymer for water trees phenomenon. The polymer used in this experiment is locally produced in the laboratory. All samples that exposed to the same electric field and different pH level were examined after a period of approximately 240 hours. The XLPE samples were then examined under the optical microscope. A numbers of water tree found in the aged XLPE sample. It was found that the propagation rate of water tree growth in acidic solution is proportional with the acid level. The conductivities in high acid level leads to large growth of water tree. The growth rate reduces in less acidic solution. The conductivity of the acid solution depends on the concentration of ions in the solution. Those that ionize the most are the most acidic; those that ionize the least are least acidic. The effect of temperature is also obtained from this experiment.