12 Technical data
12.11
STO [X3]
Characteristic values
Characteristic
Value
Safety level
Category 4 and performance level
e or SIL3/SIL CL3.
PFH (probability of dangerous failure per hour)
3 x 10
–11
PFD (probability of dangerous failure on demand)
5 x 10
-6
DCavg (average diagnostic coverage)
High
MTTFd (mean time to dangerous failure)
Limited to 100 years (cat. 3)
Limited to 2,500 years (cat. 4)
For further characteristics, see the type examination certificate in section 15
Proof-testing of the STO function
Comply with the following test intervals in order to reach the specified values:
l
For SIL 2, PL d/category 3: 1x per year
l
For SIL 3, PL e/category 3: every 3 months
l
For SIL 3, PL e/category 4: daily
12.11.1
Electrical data of the STO function
Control inputs STOA/STOB [X3]
Characteristic
Value
Nominal voltage
24 V (referred to GNDA/GNDB)
Voltage range
19.2 V… 28.8 V
Permissible ripple
2 % (referred to a nominal voltage of 24 V)
Nominal current
20 mA typ., 30 mA typ.
Switch-on input voltage threshold >= 16 V
Switch-off input voltage threshold < 5 V
For the technical data of the digital inputs DIN6 and DIN7 or of the digital output DIN0, see
the section 12.10
Product manual BL 4000-C
Page 230 of 298