Investigation of varistors frequency response and coordination with transient voltage suppression diodes

The frequency response of metal-oxide varistors and transient voltage suppression diodes is experimentally investigated; their voltage-current characteristics are measured by employing DC, sinusoidal, and pulse overvoltages. The effective coordination of varistors with transient voltage suppression diodes is evaluated by performing experiments with exponential and rectangular impulse currents; experimental results are in good agreement with preliminary ATP-EMTP simulations.