A Study of the Mutual Coupling between a Three-Phase Power Line 115 kV and a Parallel Telephone Line By using ATP/ EMTP : Case Study Distribution Line in Thailand Alarm

This paper deals with the unwanted mutual coupling of a three-phase power line 115 kV to a parallel telephone line. This phenomena naturally occurs whenever a line is energized. As a result, a adjacent line is linked with both electric and magnetic field. 115 kV distribution system in Thailand is selected in this study. ATP/EMTP is a powerful tool which is utilized for modeling a three phase power and telephone line that are assumed as a solid line with the restricted program. That means that the insulation effect from the telephone cable is negligible. The simulation result is verified with field tests. The comparison of results shows a good agreement of 10.53 V averaged induced voltage on telephone line which is excessive compared with mutual coupling standard for ADSL applications. In addition, the induced voltage effect when considering the following factors: the height of telephone line above ground, the length of telephone line in each section and the amplitude of current in power line is investigated