Servotronix CDHD2S - STO Functional Safety Specification; STO System Requirements

Troubleshooting
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CDHD2S
2A
AC 120/240V
1.5A, 3A
STO_A3
Yes*
CDHD2S
2B
AC 120/240V
4.5A, 6A
STO_A3
Yes*
9.3 STO Functional Safety Specification
Note: At present, the STO function of all CDHD2S models are waiting for certification.
Table 9-2
Features
Specification
Performance level
Meeting 4PLe category (ISO13849-1)
Safety integrity level
Meeting SIL3 (IEC61508/IEC62061/61800-5-2)
Reliability data
SFF
MTTFd
PFH*
PFDAVG**
PL
Cat.
98.9%
66757.5
1.71E-9
1.5E-4
e
4
*Failure probability per hour
**On-demand failure probability, calculated based on annual demand.
Figure 9-1 STO circuit wiring
9.4 STO system requirements
STO power supply
To avoid excessive voltage levels at the STO input, safety-related parts must use low voltage.