Resistive Coupling Effect to Customer Premises Equipment (CPE) due to Non-Equipotential Earthing System

摘要

Even though the International Telecommunication Union-Telecommunication Sector (ITU-T K.21) already imposed on a guideline for over voltages and over currents testing methodology for customer premises equipment, the full adoption of solely on this standard may not be sufficient without taking into account on surge protection devices (SPD) installation and a proper earthing system and bonding configuration as mentioned in ITU-T K.66. There is a high possibility of resistive coupling may occur to the CPE or more specific to a Digital Subscriber Line (DSL) modem when two isolated earthing system that really exists between a distribution point's (DP) earth with that of power utility's earth. Thus, it will create a stray surge current to be discharged indiscriminately which causing a complete circuit within the PCB (printed circuit board) of DSL modem itself as a result of insulation breakdown. Moreover, it is worsened by the presence of lightning-induced surges in multi-pulse via telephone and power cables since neither ITU-T nor International Electrotechnical Commission (IEC) has imposed high priority on these issues.