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FIM Products
MTBF CALCULATION
Based on 10 years of tests results, we have established thefollowing relationship.The failure rate λ
Β depends on the hot spot temperature θ
HS and the charge ratio ρ : ρ = V
w /V
n 4.425( ρ - 1) -9 λ
Β = 10 e
[
2.087 ( _________ θ HS+273) 15 343 ]
10 in failures/hour
GENERAL FAILURE RATE
λ = λ
Β π
Q π
Β π
E failures/hourWhere π
Q π
Β and π
E are factors found in the following tables.
MEAN TIME BETWEEN FAILURE (MTBF)
M.T.B.F. = 1/ λ hours
SURVIVAL FUNCTION
N = No. exp(- λ t)N is the number of pieces still working after t hours, No is thenumber of pieces at the origin (t=0). QualificationQualification factor π
Q Product qualified on IEC 610711 and internal qualification Product qualified on IEC 610712 Product answering on another norm5Product without qualification15 EnvironmentEnvironment factor π
E On ground (good conditions)1 On ground (fixed materials)2 On ground (on board)4 On ship9On plane15 EnvironmentEnvironment factor π
Β Favorable1Unfavorable5 5