Exercise: „Reliability and availability · MTBF MTBF MTBF h MTBF MTTR MTBF A sys A sys A BC...
Transcript of Exercise: „Reliability and availability · MTBF MTBF MTBF h MTBF MTTR MTBF A sys A sys A BC...
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Exercise: „Reliability and availability“
Additional task 1:
The system with the machines of availability types A, B and C represented below is to be
tested for its total availability.
The used machine types have the following availabilities:
Typ B: VB = 0,95
Typ C: VC = 0,9
The total availability of system is to be VSYS=0,9. For machines of availability tpye A an
average time for repairs can be ensured in case of machine failure.
Which demands have to be made on the downtime behavior of the machine with
availability type A?
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!74,19908,01
2908,0
2908,0
908,0
908,09914,0
9,0
9914,0
9914,0
9914,0)855,01()9405,01(1
855,09,095,0
9405,099,095,0
99,0)9,01()9,01(11
failurestwobetweentimeAveragehh
MTBF
hMTBFMTBF
MTTRMTBF
MTBFA
sys
A
Asys
BC
BCunten
BCoben
C
Additional task 2:
A lifting-sinking station was investigated by an analysis of the current state. Thereby, the
following data were gained:
Number of repairs M = 6
Number of failures N = 7
cumulated operating time tE = 520 [h]
cumulated downtime tA = 39 [h]
What is the value with which the availability of the lifting-sinking station can be estimated
with an error probability of α = 0,05?
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909,034,335,33
35,33
34,3)!(336,23
392
35,33)!(845,28
)39520(2
975,02
05,01
21
2
)(2
,
2
)2
1(;2
2
)2
1();1(2
u
o
u
M
Ao
n
AEu
ou
uu
TabelleausMTTR
TabelleausMTBF
tMTTR
ttMTBF
wobeiMTTRMTBF
MTBF
Source: Universität Karlsruhe
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