Indirect reliability estimation for electric devices via a dynamic “stress – strength” model

In the paper, the problem of an efficient assessment or estimation of the reliability function of power system devices subjected to repeated “shocks” (e.g. overvoltages) is dealt with. The adopted model is a dynamic “Stress-Strength” model, leading to an Exponential reliability model, whose parameters are functions of electric system parameters or characteristics (e.g., frequency of overvoltages occurrence, their amplitude distribution, the degradation law of component insulation, etc). By adequately using the engineer’s knowledge about such parameters, a so called “indirect estimation” of reliability function or related parameters (lifetime quantiles, MTTF, etc.) can be developed with no particular difficulty, as illustrated in the paper by means of some numerical applications, performed via the Classical estimation theory. The indirect estimation may be often more efficient than the “direct one”, which must be often based upon too few lifetime data.