Delta CFP2000 Series User Manual page 749

Chapter 18 Safe Torque Off Function│CFP2000
18-1 The Drive Safety Function Failure Rate
Item
STO
HFT
(Type A subsystem)
SIL
PFH
PFD
av
Category
PL
MTTF
d
DC
18-2 Safe Torque Off Terminal Function Description
The Safe Torque Off function is to cut off the power supply to motor through the hardware, thereby
the motor could not produce torque.
The STO function controls the motor current driving signal through two hardware circuits respectively,
and thus cut off the inverter power module output in order to achieve the status of safety stop.
Operation Principle Description as following table 1:
Table 1: Terminal operation description
Signal Channel
STO1–SCM1
STO signal
STO2–SCM2
Driver Output status
 STO means Safe Torque Off
 STL1–STL3 means Safe Torque Off hardware abnormal.
 STL3 means STO1–SCM1 and STO2–SCM2 internal circuit detected abnormal.
 STO1–SCM1 ON (High): means STO1–SCM1has connected to a +24 V
 STO2–SCM2 ON (High): means STO2–SCM2 has connected to a +24 V
 STO1–SCM1 OFF (Low): means STO1–SCM1hasn't connected to a +24 V
 STO2–SCM2 OFF (Low): means STO2–SCM2hasn't connected to a +24 V
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
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 (High)
STL2 mode STL1 mode
(Torque output (Torque output
off)
18-2
Performance
Channel 1: 80.08%
Channel 2: 68.91%
1
SIL 2
SILCL 2
9.56×10
-10
4.18×10
-6
Category 3
d
High
Low
OFF (Low)
OFF (Low)
STO mode
(Torque output
off) off)
power supply.
DC
power supply.
DC
power supply.
DC
power supply.
DC