JUMO 701150 14597 safetyM STB/STW - Safety Temperature Limiter and Safety Temperature Monitor Operating Manual - Manual (Page 42)

6 Safety Manual 2014-05-01 42
6.8.2 Failure rates and SFF for 701150...25 (AC/DC 24 V)
Important information:
Variants 1 to 4 were evaluated with JUMO probes according to data sheets 901006 and 902006.
For variant 5 no sensor system was taken into account.
In this case, the user selects the sensor system.
The PFH and PFD
avg values were calculated with the assumption that the time to restore the system is 8 h (MTTR = 72 h). Fur-
thermore, the calculation was based on a lifetime of 10 years (T 1 = 10 y). The Common Cause Factor was determined accord-
ing to the tables of DIN EN 61508 for sensor systems and logic.
Variant
λ
s
[Fit]
λ
dd
[Fit]
λ
dd
[Fit]
SFF
PFH (1/h)
PFD avg
1 799.3 306.32 33.61 96 % 6.59 e -9 2.91 e -4
1a 799.3 306.32 33.61 96 % 3.07 e -9 1.35 e -4
2 802.26 303.36 33.61 96 % 3.07 e -9 1.35 e -4
3 827.25 324.71 37.91 96 % 3.13 e -9 1.37 e -4
4 833.31 341.75 39.81 96 % 3.23 e -9 1.41 e -4
5 818.96 323.07 36.26 96 % 3.05 e -9 1.33 e -4