This means that the assessment of damage probability ร needs only to integrate the distribution density function of stresses in the limits from ร of breakdown voltage to infinity. The result is illustrated in Figure 8.7 by shadowed surfaces ร and ร for two cases – before the reduction of stresses (overvoltages) and after it.
The considerations as given above may be extended to some other kinds of stresses, generally marked by symbol ร instead of symbol ร. This extension needs only to insert into equation (8.32) the general symbol ร or other relevant symbol, yielding