Delta VFD11AMS21AFSHA, User Manual

Page: 438 / 445

Chapter 17 Safe Torque Off Function

MS300
(High Speed Model)
17-5
17-4 Failure Rate of the Drive Safety Function
Please refer to Table 3 below for
relevant
safe parameters of safe loop:
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 3: Relevant safe parameters of safe loop
17-5 Reset the Parameter Settings
Pr. 06-44 can be used to set the reset method when an STO alarm occurs.

STO Latch Selection
Factory setting: 0
Settings 0: STO Alarm Latch
1: STO Alarm no Latch
 Pr. 06-44 = 0 STO Alarm Latch: after the reason of STO Alarm is cleared, a Reset command is
needed to clear STO Alarm.
 Pr. 06-44 = 1 STO Alarm no Latch: after the reason of STO Alarm is cleared, the STO Alarm will
be cleared automatically.
 All of STL1~STL3 error are “Alarm latch” mode (in STL1~STL3 mode, the Pr. 06-44 function is
not effective).