ABB FSO-12, User Manual

Page: 376 / 388

376 Technical data
Safety data

General
T
o determine the SIL/PL capability of the whole safety function where the FSO is
included, the failure rates (PFD
avg
/PFH) of all components implementing the safety
function (see the figure below) must be added.
• FSO module with its subsystems . The FSO acts as the logic part in the safety
function. Safety data for different subsystems is shown in section Basic safety
data on page 378 . Safety data for some typical configurations of these
subsystems is pre-calculated and shown in section Safety data for some typical
configurations on page 380 .
• Drive STO . All safety functions implemented with the FSO utilize the drive STO
as the actuator. For the safety data, see the drive hardware manual.
• SLS function. SLS always use the Speed measurement subsystem.
• SMS function. SMS function utilizes only FSO's subsystems Speed
Measurement, Logic 2 and STO output. SMS function is not controlled by inputs,
and it does not control any outputs.
• Functions which monitor the ramp speed (eg, Emergency stop function).
These functions do not contain the Speed measurement subsystem, as the speed
monitoring is implementing diagnostics, not the actual safety function.
Digital
input
STO
output
Digital
output
Speed
measure-
ment
1)
Drive
STO
Switch,
input
device
Logic
Additional
actuator,
eg. relay or
cascaded
FSO
FSO Drive
The safety data of the FSO and the drive is composed of the safety data of the
subsystems used in the FSO and the safety data of the drive STO.
1)
The Speed measurement subsystem of the FSO is only included in those safety
functions that measure the speed of a motor. For example, the Prevention of
unexpected start-up or the SSE with stop category 0 (drive coasts to a stop) do not use
the speed measurement subsystem.