BERTHOLD TECHNOLOGIES LB4710-080 - Page 31

Chapter 3 Functional Safety
Mini-Switch LB 471
31
The time trend of PVD
avg
is nearly linear to the operating time in
the period up to 10 years. The above mentioned values apply only
to the T
Proof
interval, according to which a recurrent performance
check has to be carried out.
Time-dependent trend of PFD
avg
Time-dependent
trend of PFD
avg
PFD
avg
T
Proof
1
5
10
1
2
3
4