Performance of high voltage protection cards used in digital telephone exchanges

Surge voltages and currents in low ac power circuits essentially occur due to natural lightning and switching phenomena. The other source of surge occurrence is probably due to the interaction of power systems and communication system. The damages caused due to these phenomena to telecom equipment or modules create undesirable loss of service to the society. This paper presents the simulation and experimental investigations carried out on two types of high voltage high current protection cards used in digital telephone exchanges. Special efforts were made to fabricate the surge generators as per the prescribed standards. The experimental results on the performance of two types of high voltage protection (HVP) cards for combination wave (1.2/50μs open circuit voltage and 8/20μs short circuit current) and ring wave surge voltages (100kHz 0.5μs) are studied, analyzed and presented.