The average value ร depends on the features of the individual equipment and is decisive for the damage. In the case of very sensitive equipment it may be damaged at relatively low overvoltages, because the condition ร(ร) ร is usually fulfilled. To avoid the damage, the expected overvoltages must be effectively reduced, which, for example, means that their distribution curve needs to be shifted to the left side as is shown in Figure 8.7. The shaded surface ร has been reduced to the dimensions of the surface ร.
Thanks to the condition in equation (8.30), the damage probability expressed by equation (8.27) may be significantly simplified as follows: