ABB FSO-21, User Manual

Page: 64 / 540

64 Safety functions
You can configure one or two safety functions in the same cascaded system
(Cascade A and Cascade B). If the whole cascaded system must trip after reaching a
trip limit of any safety function, or with a safety fieldbus failure, you must cascade the
SSE function.
If an FSO module activates the STO function (after a limit hit, an STO request from
the I/O or the safety fieldbus, or after an internal fault), also the cascaded SSE output
is triggered.
Note : When several drives are linked together in a master/follower system and the
follower drive is in the torque control mode, stopping functions with a deceleration
ramp (SSE with emergency ramp and SS1) will turn the follower drive to the speed
control mode. For more information on the master/follower functionality in the drive,
see the firmware manual.

Mute time feature
WARNING! The mute time increases the response time of the safety system.
This must be considered in the design of the safety system.
Mute time feature with the safe speed estimation
When there are spurious transients in safe speed estimate, you can suspend speed
monitoring with mute time to prevent unnecessary trips in the safety system. The
transient mute time can be set to cover the transient situation with the parameter
FSOGEN.31 Transient mute time . This transient mute time covers limit hits,
monitoring start, and zero speed limits.
It is also possible to use function-specific mute times for limit hit situations in SLSx,
SMS, and variable SLS functions with the safe speed estimate (starting from FSO
rev. J). Mute times for each of these functions can be set independently. In addition,
they can be set longer than the transient mute time
FSOGEN.31 .
By default, these function-specific mute times are disabled, and the value set to
parameter
FSOGEN.31 Transient mute time is used in limit hit situations instead.
Function-specific mute times for limit hit situations of the SLSx and variable SLS
functions can be enabled with the parameter
FSOGEN.38 Enable SLSx mute times .
After the SLSx specific mute times have been enabled, the following mute time
parameters are used in limit hit situations.
• SLSx.17 Mute time for SLS1
• SLSx.27 Mute time for SLS2
• SLSx.37 Mute time for SLS3
• SLSx.47 Mute time for SLS4
• SLSx.57 Mute time for variable SLS