Unavailability Analysis for k-out-of-n:G Systems with Multiple Failure Modes Based on Micro-Markov Models

Table 2

Comparison of PFD_avg equations only considering the DU failure.

System type	This paper	IEC equation	Reference [16]	Reference [20]	Reference [4]
1oo1	𝜆DU𝑇1/2	𝜆DU𝑇1/2	𝜆DU𝑇1/2	𝜆DU𝑇1/2	𝜆DU𝑇1/2
1oo2	(𝜆DU𝑇1)^2/3	(𝜆DU𝑇1)^2/3	(𝜆DU𝑇1)^2/9	(𝜆DU𝑇1)^2/4	(𝜆DU𝑇1)^2/3
2oo2	𝜆DU𝑇	𝜆DU𝑇	2⋅𝜆DU𝑇/3	𝜆DU𝑇	𝜆DU𝑇
2oo3	(𝜆DU𝑇1)^2	(𝜆DU𝑇1)^2	(𝜆DU𝑇1)^2/3	3(𝜆DU𝑇1)^2/4	(𝜆DU𝑇1)^2
1oo3	(𝜆DU𝑇1)^3/4	(𝜆DU𝑇1)^3/4	—^a	—^a	(𝜆DU𝑇1)^3/4

aThe PFD_1oo3 equation is not given in [16, 20].