Delta VFD2A7MS43ANSAA

Chapter 17 Safe Torque Off FunctionMS300
771
17-4 Failure Rate of the Drive Safety Function
Refer to Table 17-3 for the relevant safe loop parameters.
Item
Definition
Standard
Performance
SFF
Safe failure fraction
IEC61508
S1–DCM = 88.35%
S2–DCM = 88.2%
HFT
(Type A subsystem)
Hardware fault tolerance
IEC61508
1
SIL
Safety integrity level
IEC61508
SIL 2
IEC62061
SILCL 2
PFH
Average frequency of dangerous failure
[h-1]
IEC61508
1.36 x 10
-9
PFD
av
Probability of dangerous failure on
demand
IEC61508
5.99 x 10
-6
PTI
Proof test interval
IEC61508
1 year
Category
Category
ISO13849-1
Category 3
PL
Performance level
ISO13849-1
d
MTTF
d
Mean time to dangerous failure
ISO13849-1
High
DC
Diagnostic coverage
ISO13849-1
Low
Table 17-3: Relevant safe loop parameters