The use of metal-oxide varistors in surge protection modules for telecommunication systems was evaluated. For this purpose, the definition of the device model and its voltage-current characteristics we defined and analyzed in detail. A high voltage impulse generator was developed to generate double exponential currents, in order to recreate the effects of indirect lightning strikes and switching overvoltages. As a result, an experimental setup was developed to record the time response of different nonlinear protective devices. This paper describes the voltage-current characteristics of small packaged varistors and the relation between numerical simulation results and the data recorded from the actual impulse testing of such devices. Additionally, it is intended to be use by engineers and system designers as an initial approach for selecting the adequate nonlinear protective device for telecommunication systems.
