ABB FSO-21, User Manual

Page: 370 / 540

370 Configuration
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Defining the scaled SLS4 limit and SLS4 trip limits
Because the same scaling percentage is used to scale both the original SLS4 limit
and SLS4 trip limit, this affects the difference between new, scaled SLS4 limit and
SLS4 trip limits. The FSO scales the SLS4 trip limit so that the difference between the
new limits does not become too small.
The FSO module first scales the original SLS4 and SLS4 trip limits with the given
percentage. If necessary, the new, scaled SLS4 trip limit is the adjusted according to
these rules when safe speed estimate is used:
• If the difference between original SLS4 and SLS4 trip limits < 25 rpm:
the difference between the scaled limits is the same as the original difference.
See Example 1 below.
• If the difference between original SLS4 and SLS4 trip limits > 25 rpm:
the difference between the limits is at least 25 rpm. See Example 2 below.
• Regardless of the original difference between the limits, the scaled SLS4 trip limit
must always be at least the zero speed value (parameter FSOGEN.51 ).
If an encoder is used, the rules become:
• If the difference between original SLS4 and SLS4 trip limits < 5 rpm:
the difference between the scaled limits is the same as the original difference.
• If the difference between original SLS4 and SLS4 trip limits > 5 rpm:
the difference between the limits is at least 5 rpm. See Example 3 below.
• Regardless of the original difference between the limits, the scaled SLS4 trip limit
must always be at least the zero speed value (parameter FSOGEN.52 ).