Delta VFD-ED Series

Chapter 16 Safe Torque Off Function | VFD-ED
16-2
16-1 Failure Rate of the Drive’s Safety Function
Item Definition Standard Performance
SFF Safe Failure Fraction IEC61508
Channel 1: 80.08%
Channel 2: 68.91%
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 9.56×10
-10
PFD
av
Probability of Dangerous Failure on Demand IEC61508 4.18×10
-6
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 16-1