Delta C2000 Series User Manual page 685

20-1 The drive safety function failure rate
Item
SFF
HFT (Type A
subsystem)
SIL
PFH
PFD
av
Category
PL
MTTF
d
DC
20-2 Safety Torque Off terminal function description
The safety Torque Off function is to cut off the power supply to motor through the hardware,
thereby the motor couldn't produce torque.
The safety Torque Off function is respectively by two independent hardware to control the motor
current drive signal, and thus cut off the inverter power module output in order to achieve the
status of safety stop.
Operation principle Description as below table 1:
Table 1: Terminal operation description
Signal
STO1~SCM1
STO
signal
STO2~SCM2
Driver Output status
STO means Safe Torque Off
STL1~STL3 means Safety Torque Off hardware abnormal.
STL3 means STO1~SCM1 and STO2~SCM2 internal circuit detected abnormal.
STO1~SCM1 ON(High): means STO1~SCM1has connect to a +24VDC power supply.
STO2~SCM2 ON(High): means STO2~SCM2 has connect to a +24V power supply.
STO1~SCM1 OFF(Low): means STO1~SCM1hasn't connect to a +24VDC power supply.
STO2~SCM2 OFF(Low): means STO2~SCM2hasn't connect to a +24VDC power supply.
Definition
Safe Torque Off
Hardware Fault Tolerance
Safety Integrity Level
Average frequency of dangerous
failure [h-1]
Probability of Dangerous Failure on
Demand
Category
Performance level
Mean time to dangerous failure
Diagnostic coverage
Channel
ON(High)
ON(High)
Ready
Standard
IEC61508
IEC61508
IEC61508
IEC62061
IEC61508
IEC61508
ISO13849-1
ISO13849-1
ISO13849-1
ISO13849-1
Photo-coupler status
ON(High) OFF(Low)
OFF(Low) ON(Low)
STL2 mode STL1 mode
(Torque (torque
output off) output off)
Performance
Channel 1: 80.08%
Channel 2: 68.91%
1
SIL 2
SILCL 2
-10
9.56×10
-6
4.18×10
Category 3
d
High
Low
OFF(Low)
OFF(Low)
STO mode
(Torque output
off)
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