Aging of the over-voltage protection components

The aim of this work was to examine the influence of the number of activations, i.e. over-voltage pulses, on the aging of over-voltage protection elements. Both nonlinear (gas-filled surge arresters (GFSA), varistors, over-voltage diodes), and linear (capacitors-constituents of filters) over-voltage protection elements were tested. The instruments used allowed reliable measurements, and 1000 consecutive activations were carried out. A current pulse, (I^max=13 A, 16 A; T₁/T₂=8/20 μs) for non-linear elements and a double exponential over voltage pulse (1.2/50 μs) of amplitude 320 V, 480 V and 640 V for capacitors was used. The experimental results showed that the over-voltage diodes are the most reliable elements, considering changes of characteristics as a result of aging. It was observed however that varistors, GFSAs and capacitors suffered noticeable changes in characteristics.