Safety Data; General - ABB FSO-21 User Manual

Safety data



General

T
o determine the SIL/PL capability of the whole safety function where the FSO is
included, the failure rates (PFD
function (see the figure below) must be added.
Switch,
input
device
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.
• 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
data on page 433. Safety data for some typical configurations of these
subsystems is pre-calculated and shown in section
configurations on page 435.
• 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.
/PFH) of all components implementing the safety
avg
FSO
Digital
input
Logic
Speed
measure-
1)
ment
Technical data 431
Drive
Drive
STO
STO
output
Additional
actuator,
Digital
eg. relay or
output
cascaded
FSO
Safety data for some typical
Basic safety